Diagnostic Atlas of Veterinary Ophthalmology

Second Edition

Dr Keith Barnett Consulta nt Ophthalmologist, Centre for Sma ll Animal Studies, Animal Health Trust, OBE, MA, PhD, DVOphthal, FRCVS, DipECVO

MOSBY

ElSEVIER

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MOSBY ElSEVIER

III KC Barnet! 1990 CI 2006, Elscvler Umiled, All righl$ reserved.

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Contents

Acknowledgements vii

Preface viii

Chapter 1 Globe and Orbit 1 Introduction 1 Enophthalmos 2 Exophthalmos 2 Pro lapse 4 Microphthalmos 4 Buphthalmos 6 Hydrophthalmos 6 Phthisis bulbi 7 Strabismus 7 Nystagmus 8

Chapter 2 Upper and Lower Eyelids 9 Introduction 9 Entropion 10 Ectropion 13 Distichiasis 14 Ectopic cilia 14 Trichias is 16 Blepharitis 16 Meibom ian itis 18 Hordeolum 18 Meibomian cyst 18 Eyelid neoplasia 18 Congenital anoma lies 21

Chapter 3 Nictitating Membrane 23 Introduction 23 Prominence of the nictitating

membrane 23 Trauma and foreign bodies 23 In flammation 23

Prolapse of the nictitans gland 26 Deformity of the cartilage 26 Neoplasia 27

Chapter 4 Lacrimal System 29 Introduction 29 Punctal abnormalities 30

Chapter 5 Conjunctiva, Limbus, Sclera 35 Introduction 35 Conjunctivitis 35 Chemosis 37 Conjunctiva l haemorrhages 37 Subconjunctival masses 38 Symblepharon 38 Foreign bodies 41 Conjunctival dermoid 41 Conjunctival cyst 41 Neoplasia 42 Scleritis and episc leritis 42

Chapter 6 Cornea 47 Introduction 47 Keratitis 48 Corneal ulcers 52 Keratoconjunctivitis sicca (KCS) 53 Corneal oedema 60 Lipid keratopathies 63 Corneal sequestrum 65 Trauma and foreign bodies 66 Neoplasia 68 Congenita l anomalies 68

Chapter 7 Uvea l Tract 69 Introduction 69 Clinica l signs of anterior uveitis 70

COlltellt5

Sequelae 70 Cysts 78 Neoplasia 78 Congenital anomalies 78

Chapter 8 Glaucoma and Aqueous 89 Introduction 89 Clinical signs 90 Primary hereditary glaucoma

in the UK 93 Secondary glaucoma 93 Gonioscopy 94 Aqueous 96

Chapter 9 Lens 97 Introduction 97 Primary hereditary non-congenital

cataracts 98 Congenital cataracts and

associated anomalies 106 Cataracts secondary to another

eye disease or condition 110 Metabolic, toxic and nutritional

cataracts 113

Other types of cataract 113 False cataracts 113 lens luxation 120

Chapter 10 Vitreous 129 Introduction 129 Congenital 129 Acquired 131

Chapter 11 Fundus 135 Introduction 135 The normal canine fundus 135 The normal feline fundus 150 The normal equine fundus 153 The normal bovine and ovine

fundus 157 The fundus of other species 160 Diseases of the retina - the

retinopathies 160

Chapter 12 The Optic Nerve 203 Introduction 203 Conditions of the optic nerve 203

ments

All the illustrations in this book are taken from the collection at the Comparative Ophthalmology Unit of the Animal Health Trust. Several were taken by colleagues and residents [ greatly enjoyed working with over a number of years. These now well-recognised veterinary ophthalmologists include Roger Curtis, Arnold Leon, Nick Millichamp, Jane Sansom, Tony Read, Beverly Cottrell, David Williams, Lorraine

Reming, Sally Turner, Christine Heinrich and Heidi Featherstone. I also acknowledge the referring veterinary surgeons, the owners and breeders and, most particularly, the animals themselves whose patience enabled us to photograph their eyes. [ should also like to thank the staff who were involved in the production of this book at Mosby Elsevier for their interest and expertise.

Preface

In my preface to the first edition, A Colour Atlas of Veterinary Ophthalmology published by Wolfe in 1990, I sta ted that the book was intended for both the practici ng veterinary su rgeon and also for the veterinary s tudent with interests in eye disease. TIlis edition Wi'tS little more than a collection of favourite photogra phs and 'although the great majority ha ve been reproduced in this second edition, together with several fu rther illus trations, I have also induded some text and tables which 1 believe may

help, together with the illustrations, in a mo re accurate di!l gnosis of the many eye conditions, incl uding many hereditary eye diseases in the dog, that have now been described . However, this book is still intended as an atlas. and I hope will provide a val uable pictorial resource for clinicia ns and com plimen t the increasing number of textbooks 011 veterinary ophthalmology.

K C Barnett

Chapter

Globe and Orbit

Introduction This first chapter covers the globe as 11 whole - and the orbit - the following chapters dealing with specific parts of the eye, e.g. eyelids, cornea, lens, fundus, etc. Therefore, some overlap is inevitable between this chapter and those that follow and certain figures depicted here could appear in subsequent chapters.

A naked-eye examination of the globe, perhaps aided by a pen torch, shou ld note the position of the globe within the orbi t and the size of the globe, together with ocular movements and the presence or absence of an ocular discharge or lacrimation. The globe should be examined from both d irectly in front and above, which will greatly assist the differential diagnosis between increased size of the globe and abnormal position of the globe.

Titbit 1.1 * Position of globe: differentia l diagnosis

Enophthalmos (+ nictitating membrane prominence)

1. Normal variant - breed-re lated. e.g. Flat*Coated Retriever 2. Unilateral or bilateral l . Pain 4. Microphthalmos, phth isis 5. Orbital neoplasia {uncommon} 6. Atrophy of orbital tissue 7. Horner's syndrome (+ miosis, ptosisl

E~ophthalmos (+ nictitating membrane prominence usual)

1. Normal variant - breed- relattd. e.g. Pekingese 2. Unilateral or bilatera l 3. Retrobulbar space-occupying lesion

Acute - Pain AbsccS5 Haemorrhage Cellulitis

Chronic - No pain Neoplasia

4. Prolapse EJcophthalmos may also be confused with an enlarged eye

{hydrophthalmos and buphthalmos]

RetropulSion, through the upper eyelid, will a lso be of help and the two eyes should be compared. A detailed examination of all the other parts of the eye should follow ilnd must include examination of the contralateral eye, evell if this appears normal on naked-eye examination (Table 1.2).

All three companion animals (horse, dog and cat) have large globes, very large and prominent in the horse. Both the dog and the cat have an open or incomplete orbit, whereas the horse has a complete bony orbital rim and an enclosed orbit.

Conditions affecting the globe and orbit can be divided into two groups:

1. Position of the globe in relation to the orbit, e.g. exophthalmos (proptosis) and enoph thalmos (Tables 1.1 and 1.2).

2. Size of the globe, e.g. microphthalmos, medical buphthalmos, hydroph thalmos, phthisis. Also note strabismus and nystagmus.

The dHferenti,ll diagnosis is not always obvious and the position, prominence or retraction of the nictitating membrane may help or confuse. Radiography and CT or preferably MRI scans can be of considerable assistance.

Table 1.2 - The painful eye

Signs

lacrimation. blepharospasm. photophobia. enophthalmos (globe retraction) in some cases. 1. Orbital disease (abscess. ce llulitis) 2. Endophthalmitis - uncommon 3. Supernumerary eyelashes 4. Eyelid abnormali ties and blepharitis 5. Keratoconjunrt i~itis sicca 6. Conjunctivitis - mild 7. Corneal ulcers 8. Uveitis (acute) 9. Glaucoma (acute)

2 Globe and Orbit

Enophthalmos (Figs 1.2-1.3) Enophtha lmos is sinki ng or recession of the globe into the orbit and has a variety of causes. Degrees of enophthAlmos are A normal variAnt in a number of dog breeds, such as the Rough Collie and Flat-Coated Retriever, with deep-set eyes and often mucus accumuJation at the inner canthus. A painful eye can be withdrawn into Ute orbit by the retractor bulbi muscle and, in Homer's syndrome, enoph-

Fig. 1.1 The normal eye (Greyhound, young adult) Note the shape and perfect apposition of the eyelids to the globe, the absence of any discharge and the regula r corneal reflection.

Fig. 1.2 young The small eye normal in certain breeds. Note the small sunken globe with prominence of the nictitating membrane.

Fig. 1.3 Enopht halmos Orbital adenocarcinoma pushing the globe backwards into the orbiL Note that in this case, due to the position of the tumour, protrusion of the nictitating membrane is not evident.

thalmos, together with ptosis and miosis, are the classical presenting signs. Enophthalmos also accom-panies a small globe in cases of microphthalmos and phthisis and is an uncommon sign in cases of orbital neoplas ia with extension of the tumour into the orbit pushing the globe more d eeply into the orbit (exophthalmos is a much more common sign with retrobulbm tumours), Atrophy of orbital tissue also leads to degrees of enophUlalmos. In all these cases, the enophthalmos is accompanied by prominence of the nictitati ng membrane.

Exophthalmos (Figs 1.4-1.8) Exophthalmos, or proptosis, is the prominence of a normal-sized globe and associated with a retro-bulbar space-occupying lesion. It is usually unila teral and often, bu t not invariably (see later), accom-panied by prominence of the nictita ting membrane. The degree of natural exoph thalmos, and enop h-thalmos, is related to breed d ifferences, e.g. the Pekingese and the Pug. Obviously prolapse (dis-location of the globe to a position in fron t of the eyelids) occu rs much more read ily i.n the brachycephalic breeds with their promi nent eyes 'and sha llow orbits, With a space-occupying retrobulbar lesion protrus ion of the nictitating membrane is usua l. Other clinical signs include strabismus, periorbital swelling. conjunctival congestion and chemosis, ocular discharge and pai n. together wi th difficulty in opening the mouth, Ca uses include retrobulbar abscess and haemorrhage and orbital

Fig. 1.4 Exophthalmos (Labrador Retriever, 8 years old) Note the prominence of both the globe, with changed shape of the palpebral orifice, and the nictitating membrane, together with mild lacrimation on the right side. This tumour proved to be a glioma of the optic nerve which was closely applied to the back of the globe and the cause of a small retinal detachment.

Fig. 1.5 Exophthalmos (German Shepherd Dog, 3 years old) Obvious prominence of both globe and third eyelid, together with periorbital swelling and ocular discharge. The retrobulbar mass proved to be a spindle cell sarcoma.

Exophlh~lmos

Fig. 1.6 Exophthalmos Prominence of the globe and third eyelid with central exposure keratitis and ocular discharge. This acute case was accompanied by pain and was due to a retrobulbar abscess.

Fig. 1.7 Exophthalmos i Springer Spaniel. aged) Chronic case with considerable prominence of the globe, together with conjunctival congestion and exposure keratitis due to inability to close the lids over the globe. The cause was a retrobulbar tumour,

4 G!obf. ;lnd Orb1t

Fig. 1.8 Elcophthalmos (Domf.stic Shorthaired cat, 9 years old) Prominence of the globe and nictitating membrane with periorbital swelli ng and change in the shape of the palpebral aperture. The cause is a retrobulbar lymphosarcoma.

cellulitis; aU carrying an acute history. Other causes include neoplasia, partiOl larly in the dog.. and have a chronic, slowly progressive, and usually non-p..linfu l, his tory.

Prolapse (Figs 1.9- 1.1O) Prolapse, sometimes referred to as proptosis, is the fonvard displacement of the globe which becomes trapped between the eyelids so preventing its return to the orbit. It always follows trauma, is rare in the ca t and horse, and is pa rt icula rly seen in the brachycephal ic breeds on account of their shallow orbits. It is always a d ire emergency; is often accompanied by optic nerve damage; and , fo llowing replacement, the eye often exhibits a divergent s trabislllus.

Microphthalmos (Rgs 1.11-1. 15) Microphthalmos is an abnorn\ally small globe; is congeni tal, and in the dog.. some cases are inherited; is unilateral or bilateral in which case the two eyes may be similar or show differing degrees. II is common in the dog, also occurs in the horse, but is rare in thecal. Microphthalmos is often accompanied by other ocular defects, particulil rly Ciltaracl whicl\

i ' .9 Eyeball prolapse (Miniature Poodle, young adult) Following trauma. the globe is trapped in front of the eyelids and prevented from returning to the orbit. Note the Intraocular and subconjunctival haemorrhage.

Fig. 1.10 Eyeball prolapse (French Bulldog) Prolapse both globes in this brachycephalic breed. following a road traffic accident. Note the absence of the haemorrhage present in the previous figure and the divergence: of both globes following the prolapse.

may well be the pn."SCn ting sign. Microphthalmos varies in the dL"gI"L:OC of severity from a small but ot herwise normal eye (nanophthalmos) to cases wi th multiple ocular defects (MOO). The microph-thalm ic eye usually shows degrees of enophthalmos accompa nied by p rominence of the nictita ting membra ne.

Fig. 1.11 Microphtha lmos puppy) Severe bilateral microphthalmos in a deaf and blind white puppy resulting from a blue merle x blue merle mating.

Fig. 1.12 Microphthalmos (Thoroughbred, foal) 'Button eye' occurs congeni tally in all breeds of horse and Is often, as in this case, accompanied by other ocular defects. This figure shows differing degrees in the two eyes of the same foal; other cases may show only one apparently affected.

Micropllthalmos

Fig. 1.1 3 Microphthalmos (Shetland Sheepdog, Note the prominence of the third eyelid and enoph thalmos in this Shetl and Sheepdog puppy.

Fig. 1.14 Microphthalmos with MOO (German Shepherd Dog, puppy) Note the dense white partial non-progressiv(' cataract, together with fine persistent pupillary membranes.

6 Globe ~"d Orbit

Fig. 1.15 with MOO I King Charl~ Spani~l, puppy) Not~ th~ iris hypoplasia and an t ~rior cataract.

Fig. 1.16 Buphthalmos (OSH cat, 9 w~~ks old) Bilat~rat cong~nilat glaucoma.

Buphthalmos (Fig 1.16) Buphthalmos is an enlllrgcd globe due to congenital glaucoma; it is congenital bul nol inherited; it is unilateral or bi latera l and is St:.'t'n more regularly in the kitten than the other species. The eye is prominent due to its increased size and the cornea is usually opaque and may be vascularized . The nictitating membrane is often retracted and there is litt le evidence of po'lin, in spite of the increase in eyeball s ize.

Hydrophthalmos (Figs 1.17-1.19) Hydrophthalmos is also an enlarged globe due to glaucoma, prima ry or secondary, hut is not congenital. The increased intraocular pressure occurs usually in adult life. Corneal changes are usually

Fig. 1.17 Hydrophthatmos (Gr~at Oan~. 7 months old) Unilat~ral cast following ~rimary glaucoma.

Fig. 1.18 Hydrophthalmos (S~alyham Twi~r, 6 y~a~ old) Ou~ to secondary glaucoma following lens luxalion. Note th~ retraction of th~ nictitating membrane in both this and th~ previous two figures with relative increased size of globe in comparison to th~ cases of txophthalmos in which th~ glob~ is of normal size.

Fig. 1.1 9 Hydrophthalmos (horse, grey) The cause of this secondary glaucoma was a ciliary body melanoma.

1.20 Phthisis bulbi sunken enophthalmic globe, again with prominence of the third eyelid. following severe trauma. Note the ocular discharge.

evident, in particular fractures in Descemet's membrane seen as grey branching lines in a more diffuse corneal oedema, sometimes with corneal vasculariza tion. The condition is painful and the eye is irreparably blind.

Phthisis bulbi (Fig 1.20) Phthisis is a shru nken and enophthalmic globe following some severe insult, trauma, inflammation or glaucoma. Again the eye is irreparably blind, the nictitating membrane prominent and the condition may be accompanied by an ocular discharge due to the small eye in a norma l-sized orbit.

Strabismus

Fig. 1.21 Strabismus Springer Spaniel, 2 years old) Convergent squint due to a retrobulbar adenocarcinoma.

Fig. 1.22 Strabismus (Boxer puppy, 9 weeks old) Divergent squint following trauma and prolapse of the Elobe.

Strabismus (Figs 1.21-1.23) Convergen t bilateral strabismus is sa id to be inherited in the Siamese breed and odd cases are seen in both the dog and horse and are sometimes congenital. Divergent strabismus of a previously prolapsed globe is common.

8 Globe and Orbit

Nystagmus Ocu lar nystagmus, intemliltent and oscilla tory, is inherited in the Sia ml'SC breed with or without strabismus. Ocular nystagmus also often accompanies cases of microphthalmos with MOD.

Fig. 1.23 Strabismus (Sh~tland Sheepdog, puppy) Unilateral cong~nital strabismus.

Fig. 1.24 N~oplasia cell carcinoma of the-.-9lobe.

"

ChaJlter

Upper and Lower Eyelids

Introduction Eyelid disease is common in the dog, cat and horse, particularly the former which exhibits several inherited anomalies, basically entropion and ectropion. Supernumerary eyelashes (distichiasis, ectopic cilia and trichiasis) also account for much eyelid disease and, in the dog, are due to an inherited factor.

Inflammation of the eyelid (blepharitis) is uncommon, as are other localized infections such as meibomianitis and cyst, chalazion and hordeolum or stye. The periorbital region carries a thin skin with a good blood supply and is sometimes involved with parasitic skin diseases such as sarcaptic and demodectic mange, ringworm infection and also atopic dermatitis.

Injuries, often full thickness, occur frequently in all species, usually due to fight wounds, barbed wire and other accidents. Suturing is often required, particularly for vertical wounds as opposed to horizontal wounds, and the excellent blood supply is an important factor in healing. A further eyelid condition in this category is ptosis or

drooping of {he upper lid, commonly seen as part of Horner's syndrome, together with miosis and enophthalmos, usually presenting as prominence of the nictitating membrane; there is a remarkably high incidence of Horner's syndrome in the UK in the Golden Retriever. Ptosis is usually idiopathic.

Neoplasia affecting the eyelids is important in all the species, particularly the aged animal. The tumour may be malignant or, more usually, benign and tumour types include papilloma, adenoma, melanoma, adenocarcinoma, histiocytoma, lym-phoma, mast cell, squamous ceJ1 carcinoma and sarcoid in the horse.

Congenital anomalies include colobomas, which may affect any part of the lid (centre or latera\), and one or both lids and eyes. Colobomas are more common in the cat than the dog or horse and may well be associated with colobomas affecting other parts of the eye. The other congenital anomaly of the eyelid is the dermoid which may extend from the eyelid onto the conjunctiva and possibly beyond. Dermoids aTe considered to be inherited in the Birman cat.

10 Upper and lower Eyelids

Entropion {Figs 2.1-2.12} Entropion. in-turning of the eyelid mi'lrgin, is common, p.lrticu larly in the dog and is breed, and to some extent age, related . It may affect upper or lower or both lids and one or both eyes. Entropion is

Fig. 2.1 Entropion (German Shorthaired Pointer. 14 weeks old) Simple lower lid entropion. Note the signs of irritation caused by the eytlid in-turning with consequent enophthalmos and prominence of the nictitating membrane and lacrimation, but no corneal chal!9e5..

i 2.2 Entropion (Chow. 8 months old) Classical uplK'r and lower lid entropion with profuse lacrimation.

affected by fad.,1 conformation. in pMticular the desired eye shape, the amount of skin. usually excessive. and wrinkles or folds in the periorbital region. In the dog entropion occurs at different ages, usually up to I year. in different breeds; occasional

Fig. 2.3 Entropion (Rottweiter, 4 years old) Upper and lower lid entropion. Note. the age in this breed and compare with the ages in the previous two figures and following two figures. Also note the small corneal opacity and ulcer.

Fig. 2.4 Entropion (Great Dane, 1 weeks old) Upper and lower lid entropion with corneal changes including vascularization.

Fig. 2.5 Entropion (Cocker Spaniel. 10 years old) Senih= upper lid entropion. See also Fig 2.14.

Fig. 2.6 Entropion (Shar Pei. 12 months old) Entropion associated with mul tiple facial folds. Note the closed eye and lacrimation.

Entropion

Fig. 2.7 (same dog as in previous figure) Note the marked enophthalmos, prominent nictitating membrane and severe corneal changes.

Fig. 2.8 Entropion (Chow. 13 months old) Corneal granulation tissue resulting from the chronic irritation due to entropion.

12 UpPt. lind lower Eyelids

Fig. 2.9 Entropion Retriever, 8 months I Typical sign of depigmentation of the lower eyelid which has bet'n rollro inwards and in contact with the tt'ar film for somt' time.

Fig. 2.10 Entropion (~mbrokt' Corgi, 6 weeks Traumatic entropion following a split eyelid.

Fig. 2.11 Entropion (oSH cat. adult) lower lid entropion.

I

Fig. 2. 12 Entropion (Dorset Horn lamb. 3 days old) lower lid entropion. Congt'nital and hereditary.

cases are not inherited ,md usually d ue to trauma (Fig 2.10). The mode of inheritance is not known but is likely to be complex because of the related factors. In the horse and sheep (Fig 2.12) it is usually congenital. Entropion due to irritation caused by the hairs of the lid margin on the cornea leads to pain and often profuse lacrimation (Fig 2.2), corneal oedema and vasculariza tion (Fig 2.7) and even

Fig. 2.13 Ectropion (8eagle, young adult) Simple lid ectropion due to too long a lid.

Fig. 2.14 Ectropion (COCkN Spaniel, aged) Senile ectropion of the lower lid. Note the low ear carriage and excess skin on the head and face. This si tuation is typically seen in the English Cocker Spaniel and note also the senile entropion of the upper lid in Fig 2.5.

Ectropion

granulation tissue (Fig 2.8), ulceration and possible globe penetration. Entropion is rare in the cal.

Ectropion (Rgs 2. 13-2. ll) Ectropion, out-turning of the eyelid margin, is uncommon but again bn.>erl and age related. It affects the lower lids and is usually due to too long a lid.

Fig. 2.15 Ectropion (Cava lier King Charles Spaniel. puppy) Ectropion of both upper and lower lids with eyelid swt'lling due to jU"lt'nile pyoderma. Nott' al~ the affectt'd muzzle.

Fig. 2.' 6 Ectropion Spaniel, young ,do Diamond eye with ectropion at the kink in the centre of both upper and lower lids complicated by entropion on either side. This situation is also seen typicallv in the St Bernard, Bloodhound and Basset Hound.

14 Upper and lower Ey~l ids

Fig. 2.17 Ectropion/entropion (St Be.rnard) Grossly abnormal diamond eye.. Note: also corneal change:s and prolapse:d nictitans gland.

Ectropion does not ciluse the irritation of entropion but exposure of conjunctiva leads to some inflam-ma tion a nd normal tear d rai nage may be affected, leading to a deglee of e piphora.

Distichiasis (Figs 2. 78-2.25) Dis tkhia sis, extra or su pernumerary eyelas hes aris ing from o r near the meibomian gland orifices, is common in the dog and inherited, usually occurring at a few months of age, sometimes younger. It is rare in olhe r species. Distichiasis may or may no t cause a clinical problem, de pend ing upon Uu,. length, d irectio n and number of the s upernumerary eyelashes. It may be accompanied by lacrimation, blepha rospasm and sometimes corneal ulce ration (Fig 2.20).

Ectopic cilia (Figs 2.23-2.26) Ectopic cilia are extra las hes emerging from the palpebral conjunctiva and usually impinging directly onto the rom e"" often causing acute blepharospasm and lacrimation, and sometimes corneal uJceration. The ectopic cilia may be single or in groups and the cond ition is us ually associa ted with d egrees of distichiasis. Again, there is a strong breed incidence.

2.18 Distichiasis (Miniature longhaired young adult) Note the long supernumerary

in the lower lid producing a slight increase in the f~:'~film but no other clinical signs a corneal

Fig. 2.19 Dislichiasis (Miniature longhai red Dachshund. 1 year old) Several shorter cilia in the lid and of different lengths. but still not causing corneal damage. or any other clinical sign. Distichiasis is particularly common in this breed.

Fig. 2.20 Distichiasis young ,d~ suptfOumtrary lashes causing a corneal ulcer.

Fig. 2.21 Distichiasis Sheepdog. young adult) Several lashes causing irritation. Note the enophthalmos and prominence of the nictitating membrane. Another breed often involved with this condit ion.

Ectopic cilia

Fig. 2.22 Distichiasis (Flat-Coated Retritver. 2 years old) Two supernumerary cilia arising from the meibomian gland openings.

Fig. 2.23 Oistichiasis and ectopic cilia (Flat- Coatf'd Retriever. young adult) Note marked blepharospasm and increased lacrimation. Another breed often exhibiting this problem.

16 Upptf and t ower Evclids

Fig. 2.24 Ectopic cilia (Flat-Coated Retr iever, 7 months old) Note the origin of the aberrant cilia well inside the upper eyelid margin.

Fig. 2.25 iii , year old) These two conditions arc frequen tly found in the sa me eye.

Sheepdog, 4 months old) Sell!:'ral potential ectopic cilia lying beneath the palpebral conjunctiva.

Trichiasis (Figs 2.27- 2.28) Trichiasis is normal facial hair in contact with the cornea and / or conjunctiva from naSt.,! folds; it is occasionally traumatic in origin.

Blepharitis (Fig 2.29-2.30) Blepharitis, eyelid inflammation, is usually associated wit h a primary dcnnatologicai problem and with secondary conjunctiva l involvement. Clinical signs depend upon the primary condition and the deglLe of severi ty il nd include ocular d ischarges sticking to the lashes and periorbi tal region, irri tation and hair 105s.

'.

Fig. 2.27 Trichiasis (~kin9est . puppy) Pronounced nasal fold. Note: the: tear streak.

Fig. 2.28 Trichiasis (~king=se:. 4 ye:ars old) Irri tation and corneal ulcer due to a nasal fold .

Bltphafltis 17

Fig. 2.29 Blepha ritis i 6 years old) Note the discharge sticking the eyelashes together. the: associated early vascular ke:ratitis and the prominence: of the meibomian gland ope:nings.

Fig. 2.30 Blepharitis Se:condary to keratoconjunctivitis sicca.

18 Upper and lower Eyelids

Meibomianitis (Fig 2.31) Meibomianitis, infl ammation of the meibomian gla nd s, may be acuteor chronic and may accompany blepharitis or conjunctivitis.

Hordeolum - external (stye) (Fig 2.32) Infection of one or more of the meibomian glands.

Fig. 2.31 M~ibomian i t is (Caval ier King Charles Spani~l, 4 years old) Note the secretion from the meibomian glands.

Fig. 2.32 Hordeolum or stye (labrador Retriever, S weeks old) Infected and distended meibomian glands.

Meibomian cyst (Fig 2.33) Meibomian cyst is the cystic distension of the gla nd and is mainly visible on the conjunctival side of the lid.

Eyelid neoplasia (Figs 2.34-2.44) Eyelid neoplasia is common, particularly in the older

Fig. 2.33 M~ibomian cyst (Seagle, young adult) Cystic distension of meibomian gland visible on the conjunctival side of the lid.

Fig. 2.34 Eyelid tumour (Golden Ret riever, 1 year old) Viral papilloma.

Fig. 2.35 Eyelid tumour Papilloma.

',;,h Setter, 7 years

Fig. 2.36 Eyelid tumour (Pembroke Corgi, 9 years old) Papilloma. Note the extension of the tumour into the substance of the lid visible only on the palpebral surface.

Fig. 2.37 Eyelid tumour (Labrador Retriever. 9 years old) Squamous papilloma.

Fig. 2.38 Eyelid tumour Melanoma.

E~lid neoplasia 19

Fig. 2.39 Eyelid tumour (Boxer, 9 years old) Mast cell tumour.

20 Uppcr and lowcr Eyelids

Fig. 2.40 Eyt:lid tumour (DSH cat, 14 yt:ars old, tabby and white) Squamous cell carcinoma In the unpigmented skin or the lOWer lid. Note the affected 3rt:a is in unpigmented skin and tht: agt: of tht: animal.

Fig. 2.4' Eyelid tumour (DSH cat, 10 years old, lymphosarcoma or the upper lid. Note the chemosis afft:cting tht: lower lid.

Fig. 2.42 old) Sarcoid.

marc, 13 years

Fig. 2.43 Eyelid tumour (Welsh pony gelding, 8 years old) Sarcoid.

dog, although occnslonnlly tumours occur in younger animals. even puppies (Fig 2.34). The type of tumour is often rclotcd to the age of the animal. Tumours, depending upon their size and position, may cause irritation, blepharosp

Upptr and lo .... er EytUds

Fig. 2.48 Evelid deformity (Labrador Retriever, 6 weeks old) Gross congenital deformity of the eyelidS.

I (labrador Retriever, 6 weeks old) Pigmented and hairy dermoid of lid and conjunctiva.

Fig. 2.50 Dermoid (Birman kitten, 10 weeks old) The condition is inherited In this breed.

Chapter

Nictitating Membrane -------------------------

Introduction The appearance of the nictitil ting membrane (third eyelid or haw) is often a presenting sign in veterinary ophthalmology and prominence. or protrusion, is the commonest cl inical cond ition and is due to 11 variety of cnuses.

Prominence of the nictitating membrane {Table3.7} Prominence, unila teral or bilateral, may be accom-panied by lacrimation and blepharospasm indicating pain, usually anterior segment, e.g. glaucoma (see also Chapter 1).

Prominence also accomp .. m ies several cond itions affecting the globe, includi ng some cases of enoph-thalmos (Fig 1.2), also exophthalmos (Figs 1.4-1.8), microphthalmos (Fig 1.13) and phthisis (Fig 1.20).

Prominence may also indic.lte tetanus (bilateral and intermi tten t in the horse); Horner 's syndrome

Ttblt 3. 1 - Prominence of nictit. t lng membrane

1. Unilateral Of bilateral 2.. Pain - anterior segment wi th globe retraction; lacrimation

and blepharospasm 3. Enophthalmos 4. uophthalmos 5. MiCfophthaJmos 6. Phthisis 7. Tctanus (bHatci31) B. Horner's syndrome (unilateral) + miosis, ptOS~ 9. Dysautonomia

10. Chronic diarrl\oca (cat) (bilateral) 11. Cartibgc dtrormity (scrolltd) (dog)

(almost inva riably uniJaleral); dys.1 utonomia in the cat (bilateral) and !l Isa, in some cases, chronic diarrhoea in this species.

A non-pigmented third eyelid will look more prominent than a pigmented third eyelid and is a common cause of concern, pa rticularly w hen affec ting one eye only (Fig 3.1>.

Trauma and foreign bodies {Figs 3.2-3.3} The third eyelid is prone to injury (Fig 3.2), both in cats and by ca ts! Also the pocket a t the inner canthus behind the third eyelid is a favouri te site for foreig n bodies, in particu lar grass awns (Fig 3.3).

Inflammation {Figs 3.4-3. 70} Both su rfaces of the nictitating membrane are covered by conjunctiva (palpebral) and may therefore exhibit fonns of conju nctivitis (see also Chapter 5). These include follicula r conjunctivi tis (Figs 3.4-3.5), chemosis (Fig 3.6) and conjunctiva l cysts (Fig 3.7).

Fig. 3.1 Promin~nct of a normal non-pigm~nt~d

~Iid.

24 Nictitating M(mbran(

Fig. 3.2 Torn and prolapstd i i nictitating mtmbr;1nt following trauma.

asptcts of tht nictitating mtmbrant and othtr palptbral conjunctiva and a not uncommon caust of lacrimation dut to tht irritation.

mtmbrant fortign body Grass awn bthind tht third tytlid. Nott tht corntal granulation tissut.

Follicular conjunctivitis cat, 1 year Nott tht dtpigmtntation in the region of the folliclts and tht Straus ocular disc:hargt.

Fig. 3.6 Chemosis (OSH cat. 11 years old) Bulbar and palpebral conjunctiva are affected. Unknown aetiology.

the nictitating membrane (Persian cat. 18 mon ths old) Bilateral. unknown aetiology.

Iflnammation 25

Fig. 3.7 Conjunctival cyst , 8 months old} Subconjunctival cyst at the base: of the third eyelid resulting in mild prominence of the third eyelid.

Fig. 3.9 Plasma ce ll infiltra tion Dog . 7 years old) Note depigmentation of the affected area. This condition frequently accompanics pannus.

26 Nictitating Membrane

Fig. 3.10 I i (German Shepherd Dog, 8 years old) Aga in note depigmentation and the accompanying pannus.

A specific, immune- ml..>ciiatecl, bila tera l but not necessMily symmetrical conjunctivitis is plasma celJ infil tra tion (Figs 3.9-3. 10) w hich frequently accom-p..lnies pannus in the German Shepherd Dog and others. Another importan t ca use of inflammation is habronemiasis in the horse.

Prolapse of the nictitans gland (Figs 3. 71-3. 12) A condition mainly seen in the dog. unilateral or more frequen tly bilateral, and usually one eye fo llowing the o ther; oft en in young d ogs including puppies, and known as 'cherry eye'.

Deformity of the cartilage (Figs 3. 13- 3. l S) Sometimes refe rred to as scrolling of the cartilage; an unusual but not uncommon cond ition, particularly in the la rger breed s of dog. but rare in other species. Bilateral or unila tera l; the ca rtilage deformity usually

Fig. 3.11 Prolapse of the nictitans gland (8ulldog, 2 years old) Note the visible free border of the nictitating membrane.

Fig. 3.12 Prolapse the nict itans gland (Bulldog, 10 weeks old) Note age and breed in this case.

results in the free border of the third eyelid rolling outwards (Fig 3.1 3), and more rarely inwards (Fig 3.14). It is another ca use of prominence of the nictitating membrane and may be accompanied by mild epiphora and mucoid d ischarge.

Fig. 3.13 Carti lag~ d~form ity (G~rma n Sh~ph~rd Dog. 7 months old) Frt~ bord~r of th~ th ird ~Ijd ro ll ~d outward~

Ncopi3sia 27

Neoplasia {Figs 3.16-3.18} Various neoplasms may be in volved but are comparatively rare in the dog and cat, although the nictitating membrane is a common site ror squamous cell carcinoma in the ho rse (Fig 3. 18), often presen ting as it case of persis tent ocular discharge.

Fig. 3.14 Cartilagt ddormity 5 ytars old) Frt t border of tht third eytl id rolled inward~

28 NiClitiJtl~!I Membfa~e

Fig. 3.15 Cartilage deformity (Great Dane. 8 months old) Similar to Figure 3. 13. but note similarity to prolapse of th~ nictitans gland (Figs 3.10-3. 11 ) and tumour (Fi.9 3.15).

Fig. 3.17 Nictitating membrane tumour (Siamese cat) Adenocarcinoma.

Fig. 3.16 Nictitating membrane tumour (Labrador Retriever. 3 years old) lymphosarcoma.

Fig. 3.18 Nictitating membrane tumour (Thoroughbred. 8 years old) Squamous cell carcinoma. Note the ocular discharge In this case. Tht: third t:yelid is a common site for this tumour in the horst:.

Chapter

Lacrimal System

Introduction The lacrimal system is responsible for two important, and o ften presenting.. clinica l signs of 'wei eye' and 'dry eye'. The lacrimal system has two functions: secretory (tcnr prod uction) to produce the important prc-corncill teaT film (ptf) and excretory (lncrimnl d1'ilinseein test - fluorescein into the conjunctival sac and Ihe appearance, o r otherwise, of., green slain aCicr a few minutes at the ipsilateral nostril (Fig 4.2) (w hen s tain appears il proves thnt Ihe nflsolacrimal duel syst(>m is pa lent but when no stain appea rs it does not prove tha t the system is blocked -resort then to irrigation. usually vi., the upper punctum).

The wet eye has two components (Table 4.1): 1. Lacrimation, o r overproduction of lears, a

common clinical cond ition denoting pain and/or inflammation nnd often nccompa nied by blepharosp .. ,sm (Fig 4.3).

2.. Epiphora, abno nnal o r imp.1ired drainage.

Fig. 4.2 Fluortscein pattney Itsl put into tht conjunctival sac and apj)(aring at tht nostril (proving pattney of tht nasolacrimal duct sysltm).

30 UJcrim~1 System

Tabl~ 4.1 - Th~ wtt cy~

l.acrim~tion (unjlat~,.1 or bllale,.U I. Anl~rior 5Cgmcnt pain wllh globe rCIr;lction 2. EnlropiCH'l 3. Ectropion 4. Dislichlasls s. Ectopic cilia 6. Tricnl~~s 7. For~ign body

8. Eyelid tumour

Epipho,. (unilateral or bllat~ral) I. Imperforate or mltfopuntta 2. Trauma 3. foreign body 4. Inrcctlon 5. NaSilI neoplasia 6. Symbl~pharon !catl

Fig. 4.3 Lacrimation An ~arly keratoconjunctivitis.

Punctal abnormalities Congenita l imperforate a nd micropuncta may present, dependi ng upon whether both upper and lower punctn are involved, as a wet eye (Fig 4.4) wi th a typical tear streak or stain (Fig 4.5) or more commonly as a purulent discharge in the horse (Figs 4.1)..4.7). One or both eyes may be involved, in addition to one or both puncta which may be either imperforate or micro. In the dog there is almost certain ly a heredi tary component with a definite breed incidence in the Golden Retriever and the English Cocker Spaniel. In the dog it is usually the lower punctum that is involved but if it were the

Fig. 4.4 Epiphora (Gold~n R~triever, 6 months old) Imperforate lower punctum.

Fig. 4.5 Tear streak (Golden Retriever. 6 months old) Typical brown staining due to imperforate punctum causing epiphora. 5(e also Fig 5.5 and note the similarity in the case of lacrimation associated with atopy.

upper punctum, with a normal lower pu nctum, the presenting sign would be unlikely to occur as the lower punctum drains the greater p

4. 14-4.15), sometimes due originally 10 a foreign body. or neoplasia affecting ad~lcenl s tructures or teeth. Perhaps the commonest cause of punctal occlusion in the cal is symblepharon (Fig 4.16; see also Figs 5.13-5.18).

punctum foal , a months old) Purule::nt ocular discharge:: with atrc::sia of the:: nasal opc::ning of the:: nasolacrimal duct - the:: usual situation in the:: ho~.

Fig. 4.7 Ocular discharge:: Mild purule::nt ocular discharge, the prc::se::nting sign of anothe::r case:: of absc::ncc:: of the nasal ope::ning of the nasolacrimal duel.

Pun~lal abnormall li~ 31

Fig.4.a The:: normal punctum in the:: lowe::r eye::lid of a d'!9

Fig. 4.9 Micropunctum (Cocke::r Spanie::l, 8 months old) Note:: the:: thicke::ne::d e::dge:: of the:: small ope::ning.

32 lacrimal Syst~m

Fig,4.10 Imperforate punctum Retriever, 6 months old) Note absence: of any opening.

Fig,4.11 Impcrforate punctum Hound. 14 months old) Note the depre:ssion in the conjunctiva covering the: opening of the lower punctum.

Fig. 4.12 Ocrlude:d punctum terrier. 6 months old) Scar tissue following trauma.

Fig, 4.13 Nasolacrimal duct i body Sheepdog. 14 months old) Grass awn protruding from the lower punctum following irrigation via the upper punctum,

, from the lower punctum following irrigation of the lacrimal system via the upper punctum.

4.15 Nasolacrimal duct infection (Rough Collie, 6 years old) Note the persistent and purulent ocular discharge and bead of pus from the lower punctum at the inner canthus.

Punctal abnormalities 33

nasolacrimal puncta (cat. young adult) Due to severe symblepharon. The nictitating membrane Is fused to the cornea and the conjunctival forn ices obliterated, together with the nasolacrimal duct puncta.

Chapter

Conjunctiva, Limbus, Sclera

Introduction The conjunctiva (bulb..r, palpebral and nictitating parts) is frequently influenced by diseases of the eyelids (Cha pter 2), nictitat ing membrane (Chapter 3), lacri m(ll system (Chapter 4) and cornea (Chapter 6). Innotllmation, or conju ncti vitis, is probably the commonest eye cond ition in vet-erinnry opht halmology, occurring in all species but with a difficult dassificMion as the exile! cause is often unknown (Table 5.1).

The conjunctiva may ind ie.lle systemic disease in all animals, the cha nges being bilateral. Examples are canine dis temper, respiratory tract viruses in both the cal and the horse. blood dyscrasias, jaundice and anaemia (Fig 5.6), Primary con-junctivitis has a va ried aetiology - often bacterial but also viril l, trauma, etc.

Conjunctivitis (Figs 5.1-5.5) Conju nctivi tis may be un ilateml or bilntcml; affect any age incl uding the neonate; and mny be primnry or secondn ry to ,mother eye disease and it may be difficu lt to decid e which is the primary condition, e.g. kemtoconjunctivitis. Conjunctivitis is not nor-mallya painful cond ition but does cause a degree of irritation and therefore may be accompanied by lacrimation and blepharospasm (Table 5.2).

T abll:" 5.1 _ Thl:" rl:"d 1:".,,:

Ul'li!atual 01 bihucral Al"Utc or chronic local ocul~r disease or S'{5tcmtc with pyrQla (bilateral) 1. Conjunctivitis

Primary or, morl:" commonly. s~condarv {ocular or systemicl Traumatic (subconjunctival haemorrhagel

2. Glaucoma Brcl:"d-spcdfic for primary, some sondalY caro Unilateral al first plesl:"ntatlon

J. Uvt:'itis Photophobia

4. Episclctltis/scleritis Ul'ICOmmon, usually 1'10 pilln

S. KffiItitis Including corneal ulw [pain)

6. Orbital disease Endophthillmilis PanoJMlIhalmltis Rl:"trobulbar [lnfiammatlon, ncopla~a) Prolapsl:"

Conjunctivitis may be acute (Fig 5.0 with clinical signs of hyperaemia. chemosis, lacrimation and a va riable discha rge. or chronic (Fig 5.2) with a duB redness, thicken ing and less and drier d ischarge. Follicular conjunctivitis (Fig 5.3) mai nly affects the palpebral conjunctiva and carries a non-specific aetiology. Atopic conjunctivitis also mainly affects the palpebral conjunctiva (Fig 5.4) and accompanies atopic dermatitis, often in the periorbital region and with an increased lacrimation (Fig 5.5).

36 Conjunctiva, Umbus. Sclera

Fig. 5.1 Acut~ purul~nt conjunctivitis (young dog) Not~ that th~ discharge is not adherent to the cornea and is washed away onto the eyelid margins by the incr~as~d lacrimation.

Fig. 5.2 Chronic i Not~ th~ dry~r natur~ of the discharge and its position and th~ cl~ar corn~a.

Table 5.2 - Conj unetivitb: dlffut!ntial diagnMls

PuJlll Intraocul~r Jlr~u rc

Conjunctivitis No changt! No change Glaucom;1 Dilates ; ~Itis Consltic\.S J.

Fig. 5.3 Follicular conjunctivitis (cat) Note some ch~mosis and ocular discharge.

5.4 Atopic conjunctivitis (Labrador Retriever, adult) Not~ the Involvemen t of the palp~bra l conjunctiva only visibl~ wh~n the lid is everted.

I';iin VISion Disch~rge

, No ch~nge Strl)US-Jlurulcnt , .. Blind I..aaimation .. Minor dfttl l.acrim;1l!on

Fig. 5.5 Atopic conjunctivitis Notr thr rxcrssive lacrimation causing a typicallrar streak and compa re with the tear streak due to epiphora in Fig 4.5.

Chemosis (Figs 5.6-5.7) Chemosis, or conjunctival oedema, usually accom-panies acute conjunctivitis or trauma and occurs particularly in the ca l (Fig 5.6) and horse (Fig 5.7).

Conjunctival haemorrhages (Ags 5.8-5. 70) Trauma is probably the commonest cause of conjunctiva l and subconjunctiva l haemorrhages and may be quite specmcu lar (Fig 5.8). However, there are a number of other ca uses of haemorrhage 10 mucous membranes that may aid djagnosis of a more serious cond ition (Fig 5.9).

Conjunc\lv;ll'Iacmonl'lages 37

Fig. 5.6 Chemosis (DSH cat. 3 years old) Conjunctival oedema in a cat positive for Chlamydia.

Fig. 5.7 Chemosis (Pony) Severe case obscuring the globe and due to trauma.

38 Conjunctiva, Umbus. Sclcr~

Fig. 5.8 Subconjunctival haemorrhage (Spaniel) Haemorrhage following a golf club injury.

I (Cocker Spaniel) Haemorrhage due to Warfarin poisoning (see also Fig ".206).

Subconjunctival masses (Figs 5. 11-5. 12) Occasiona lly retrobulbar fat may appea r subcon-junctivally and has been reported in the horse in association with the nictitating membrane. Fig 5.11 shows a rare case of conjunctival calcinosis in the dog causing a vasculnr keratitis and corneal ulcer.

Symblepharon (Figs 5.13-5.18; see also Fig 4. 16) Symblepharon is a conju nctival adhesion to the conjunctiva or com en. It is common in the cat but rnre in the dog and may be congenital or more

Fig. 5. ' 0 Subconjunctival haemorrhage This particular case was reaction to a paint stripper.

Rg. 5.11 Subconjunctival fat prolapse 8 years old)

i 5.12 Conjunctival calcinosis (Munsterlander, 5 months old) Calcinosis with bulbar conjunctiva and out~r aspect of th~ nictitating m~mbrane affected and causing a vascular k~ratitis and corneal ulcer. A rare case of unknown aetiology.

Symblepharon 39

Fig. 5.13 Symbl epharon (OSH cat, 2 years old) Adhesion of palp~bral conjunctiva to the cornea oblit~rating the conjunctival forniC6

Fig. 5.14 Symblepharon (OSH cat, 6 months old) A mild case not affecting vision.

Conjunctiva, Limbu~ Sclera

Fig. 5.15 Symbltpharon causing blindntss.

Fig. 5.16 Symbltpharon (DSH kitttn, 5 wttks old)

5.17 Symbltpharon (cat, young adult) Unilattral case: causing a narrowtd palptbral aptrturt.

Fig. 5.18 Symbltpharon I King Chartts 15 wttks old) Congtnital adhtsion of conjunctiva to cornta. This condition is rart In this sptcits.

particularly due to neonatal infectio n with FEHV-l i bums are another faclor in aetiology. Thcoondition is painless but may be acromp.1nied by discharge d ue to drainage problems; the degree is very variable, mechanically causing blindness in severe cases.

Fig. 5.19 Conjunctival fortign body (Yorkshirt Ttrritr, adult) Grass awn in tht Itft upptr conjunctival fornix.

Fig. 5.20 Conjunctival dermoid (Birman kitttn, 12 wetks old) Tht condition is hereditary in this breed.

Conjunctiva! cyst 4 r

Foreign bodies (Fig 5.19) TIle conjunctival fo rn ices arc favourite s ites fo r fo reign bodies, pa rticula rly of organic o rig in, a nd s ho uld always be searched under local a naesthesia in cases o f acute uniocular conjunctivitis often with a purulent discharge.

Conjunctival dermoid (Figs 5.20-5.22) Epibulbar dermoids occur on Ihe conjunctiva in all the species and three exam ples are shown.

Conjunctival cyst (Figs 5.23-5.24) Two exa mples are shown; the first in a puppy a nd the second, in a cat, associa ted wit h symblepharon.

Fig. 5.21 Conjunctival (Dogut dt Bordeaux. 1 ytar old) Unusual cast causing a corneal ulcer.

Fig. 5.22 Conjunctival dermoid (Crossbrtd puppy) Involvtment of conjunctiva, limbus and lateral canthus.

42 Conjunctiva. limbus. Sclera

Fig. 5.23 cyst (Golden Retriever. 6 months old)

Neopl asia (Figs 5.25-532) The conjunctiva, p.'1rticulnrly palpebral, and limbus are fa voured si tes for squamous cell carcinoma in the horse, a rela tively common tumour in this species. Exa mples are also shown of a haemangioma of the conjunctiva in a dog and a lymphosarcoma of the conju nctiva in a cal. In addition limbal melanoma in the dog is shown, a benign tu mour to be d istinguished fro m iris and ciliary bot.i y tumours in this and other species (see Chapter 7).

symblepharon cyst together with

cat)

Scleritis and episcleritis (Figs 533-5.35) Classification and nomenclature is confused and variable but these are inflammatory and usually nOIl-painFul conditions and are not neoplastic in spite of their appeara nce. Episclcritis may be nodu lar or simple (d iffuse), occu rring near to the limbus with hyperaemia of conju nctiva and oedema of adjacent cornea. TIle condition may be unilateral or bilateral and there is a predilection in the Golden Retriever. Nod ular episcierokeratitis is usually bilateral, involving more of the cornea and particu larly occurs in the Rough Coll ie and Shetland Sheepdog.

tumour Squamous cell carcinoma lower

palptbral conjunctiva and nictitating membrane.

,",,;," tumour (Connemara pony, cell carcinoma at the limbus and

bulbar conjunctiva.

Fig. 5.27 Conjunctival tumour (Hunter-type, 17 years old) Squamous cell carcinoma In a similar position to previous figure.

Fig. 5.28 Conjunctival tumour (Horse) Squamous cell carcinoma at the limbus. Note the typical pale grey appearance in this case. The horse was affected in both eyes.

44 ConJuncllva, limbus, Sclera

Fig. 5.29 Conjunctival tumour Setter, 11 yea~ old) Benign haemangloma. lower conjunctival fornix.

Fig. 5.30 Conjunctival tumour cat 11 year lymphosarcoma affecting palpebral conjunctiva and nictitating membrane.

Fig. 5.31 Conjunctival tumour (labrador Retriever, adult) limbal melanoma. Note the appearance at the limbus and adjacent seiera and particularly the lack of involvement or iris and pupil. Compare with Fig 7.41.

5.32 Conjunctival tumour (Golden Retriever, adult) limbal melanoma. Again note the appearance with no evidence of iris involvemen t. This tumour occurs particularly in this breed as well as the labrador Retriever [previous figure).

Fig. 5.33 Episcle:ritis (Gold~n R~tri~v~r) Nodular ~pisckritis. Not~ the. corneal ()(dema adjacent to th~

tumour .

. 5.34 Episcl~ri ti5 (Airedal~ Ttrri~r, 5 years old)

Diffuse ~pi5c1eriti5. Note hyp~ra~mia of overlying conjunr:tiva.

Scleritis and epi!oCleritis 45

Episcleritis (Rough Colli~, young Nodular e:pi5c1erok~ratiti5, bilateral cas~. Not~ the:

aqja~nt corneal arcus.

Cornea

Introduction Corneal disease .md keratitis are among the most common eye diseases in all the domestic animals and with a wide variety of (,lUses and appearances.

The presenting signs of corneal disease vary considerably between case, severity and cause and in it number, pilrticularly in the dog. the aetiology remains unknown. Pain is an important sign and will accompany most forms of keratitis. whatever the cause, with the classical triad of blcpharosp."1sm. photophobia and lacrimation, However, the degree of pain in cornea l disease is agai n va riable. from severe in cases of corneal ulceration and trauma, to non-existenl in cases of corneal oedema and most other fonns of opadty. The presence or absence of OCUlnf discharge, in addition to lacrimation. should be noted . as should the presence of pigment in the cornea which is more common in the dog than the other species. Corneal opacity is another variable and important presenting sign (Table 6.1), invol\,ing the whole cornea, for example in cases of corneal oedema, or only part of the cornea in cases of lipid infiltration, abscess or scar formation. The lipid kcratopathics are a complex but an important group with different appeara nces, often familial in the dog and usually with little or no effect on vision. In fact , vision loss is an uncommon sign of cornea l disease generally in spite of the his tory from U\e owner who imagines the animal cannot see because of the appearance of the eye(s). The presence or absence of corneal ulceration should also be checked by suitable staining, both at the initia l clinical examination and subsequently, if considered necessmy. The corneal reflection to a light sou.rce can be most useful in deciding the depth of the lesion within the cornea; for example

the reflection may be broken or im.'gular (Fig 6.1) indicating a superAcial lesion with interference of the corneal epithelium, or regular (Fig 1.1 ) indicating no interference with the epithelium. the lesion being within the cornea l stroma or endothelium.

Kerati tis may be accompanied by conjunctivitis (keratoconjunctivitis) and also. if severe or chronic, by uveitis which may well require additional treat men!. Forms of keratitis may occasionally indicate systemic involvement.

Congenital and hereditary abnormalities affecting the cornea are uncommon - the epibu lbar dermoid and microcornea being the most important of the congenital anomalies. However, certain spec.iAc corneal conditions have an interesting il nd signiAcant breed susceptibility in the dog, for example keratoconjunctivitis sicca in the West Highland White Terrier, pannus in the German Shepherd Dog, corneal lipidosis in the Shetland Sheepdog and others. Corneal tumours are also relatively mre, alt hough squa mous cell carcinoma, pa rticularly in the horse, is important. Cornea l cysts are very rare.

The main responses to corneal insult are 0 ) oedema, (2) vascularization ilnd (3) pigmentu tion and illly or 011 of these may act as presenting signs bu t are not, in lhemselves, specific d iseases.

The classifi ca tion of corneal disease is complex; it is perhaps best categorized by aetiology bu t the cause of a number of conditions is still not known. Cornea l d isease will be described here and illustrated u.nder scveral headings, although it must be reali.zed that certain speciAc conditions can be included in more than one section.

48 CarMa

Table 6.1 - Cornul opacity: differential dillgno$i~

Unil~teral 01' bilateral Partial or complete Diffuse or de~ Temporary 01' permanent 1. CornulOCilema

Neonate PUP9V Endoltlehal dcgeneratron. e.g. Chitluatl~ COlneal ulcer "ith loss of qllltlelium Corneal "GUnd or bu.n Uvcltis ('blue cyt.) Glaucoma 1+ conjunctival OCiIema) Dcsc:tmet's membrane lears Anterior lens luutlon - subccntrai, Ol/ilt Anterior scgment neoplula (uvcal mclanoma)

2. lipid kcralopathles (Infiltrations and degcneratlons) J. Corneal abscess 4, Corncal scar 5. Congenitallln\crlor synechia [pcrslstent pupillary membrane) 6. Conjunctival adhesion (symblepharon) 1. EplbulbM (rornul) dc/mold

Keratitis (Ags 6.1-6.5) Su perficia) Interstitial (stroma l) Punctate Pigmentary Exposure Chronic superfidal (pannus) Eosinophilic keratitis (ca t) Fungal keratitis (horse) Infectious bovine keratoconjunctivitis (cattle).

Chronic superficial kerotitis (pannus) (Figs 6.6-6.12) Pannus is a Iype of superficial vasculilr keriltitis often with late.r pigmentation. It is usually bilateral but not necessarily sym metrica l; often one eye is more severely affected tha n the other. Pain and discharge are moderate and blepharospasm is usually present. The d isease is immune-med iated with a strong tendency to recur with cessation of treatment A conjunctiva l component is invariably present and frequently the nictitati ng membrane is involved with a plasma cell infiltration (Fig 3.10). The Getman

Fig, 6, 1 Supt rficial ktratitis Nott tht blood vesstl crossing tht limbus and tht irrtgular branching; also tht untvtn corneal surfaCt with brtak up of the corneal rentction.

, , Note tht apptaranct blood vesst:ls on tht corneal side of the limbus, unlike FigUre! 6.1, and tht typical mort rtgular vascular branching.

Fig. 6.3 Punctatt ktratitis (Shetland Sheepdog) Aetiology unknown but usua!!y bilateral and the sma!! grey areas may lake fluorescein stain. Has been describtd as an epithelial dystrophy and tht SheUand Shttpdog, as in this case, is mainly involved.

Fig. 6.4 Pigmtntary keratitis Often accompanitd by vascularization, as in this case, and also fibrosis. Pigmentation is a classical sign of keratitis, particularly in the dog, and may accompany olhtr forms of keratitis, especially chronic cases, e.g. pannus (Fig 6.9), ktratoconjunctivitis sicca (Fig 6.42) or corneal oedema (Fig 6.48).

~~lili5 49

I 6.5 Exposure keratitis (Pekingest) Due to inability to spread the tear film across the whole cornea in cases of globt promintnce, as depicted here; also with lid paralysis (Fig 6.24) and keratoconjunctivitis sicca.

Fig. 6.6 I ii (pannus) (German Shepherd Dog, 3 ytars old) Early case with superficial vascularization typica!!y affecting the lower lateral quadrant

so Cornea

I 6.7 Chronic superficial keratitis (pannus) (German Shepherd Dog. 4 years old) More severe than previous case with granulation tissue. Note break-up of corneal reflection and early pigmentation from the lateral

limbus.

Fig. 6.8 Chronic superficial keratitis Shepherd Dog. 6 years old) Note in .... olvement of the whole cornea and early sca rring.

Fig. 6.9 Chronic superficial keratitis Shepherd Dog. 9 years old) Chronic case with pigmentation.

Fig. 6.10 Corneal granulation tissue (Crossbred. 6 years old) Superficial keratitis following a chemical burn.

Shepherd Dog is t.he breed usually affected but .. Iso Belgia n Shepherd Dogs and Lun:hers. Age incidence is the you ng adu ll (3-5 years) and pann us commonly, but not invariably. starts in the lower lateral quadrant, just occasionally medially.

Figures 6. 10-6. 12 show other fonns of chronic superficial kerati tis for differentia l diagnosis.

Fig. 6.11 Corneal granulation tissue (Boxer. 7 years old) Following re:curre:nt corne:al e:rosion Ise:e: also Figs 6.20-6.22).

Fig. 6.12 Corneal granu lation tissue: (Chow. 8 months old) Associated with tong-standing cast of entropion.

Kl-ratitlS

Eosinophilic keratitis (Figs 6. 13-6. 16) Typimlly seen in the cat; the muse is unknown and recurrence following treatment Is usual. as is the case with pannus. Initially eosinophilic keratitis is unilateral. later becoming bila te ral if left un treated . Diagnosis is aided by the appea rance of a number

Fig. 6.13 Eosinophilic keratit is cat, 1 year I Note: vascular ke: ratitis and gre:y plaque-like: lesion. Unilateral case and nole slight promlnenct of nictitating membrane due: to retraction of the globe: due: to pain, and mild ocular discharge.

Fig. 6.14 EOSinophilic ke: ratit is COSH cat, 3 years old) Bilate:ral case: and note: typical white spots.

, -

52 Cornea

Fig. 6. 15 i cat, 4 yl"ars old) An ~arly cas~ with fin~ vascularization and rais~d imgular whit~ spots,

of superficio l white round roised spots of different s izes and superficial vascularization; a conjunctiva l component is present. Pain is mild Witil a slight ocular d ischarge.

Fungal keratitis (Rg 6. 17) Keratomycosis In the horse has been well recognized in the USA for a number of years but only recently has been diagnosed with certainty in the UK. There are a number of different clinical presentations of ulceration with furrowing, ulceration wi th 'cake frosting' appearance and stromal abscessation. The cond ition is unila teral with moderate to severe pain and associa ted uveitis, cornea l vasculariza tion and dlemosis.

Infectious bovine keratoconjunctivitis (18K) (Figs 6. 18- 6.19) IBK or New Forest disease in cattle is usually unilateral with a cen tral opacity, leading to ulceration, surrounded by nn opaque cornea, due to oedema, and circumcorneal hyperaemia. Pain can be severe and there is an associoled iritis. Ocular d ischarge becomes mucopurulent, originally being clear profuse lacrimation. Superficia l vascularization towa rd the primary lesion occurs and the cornea dears from the periphery.

Fig. 6. 16 Eosinophilic ktratitis (DSH cat, 3 y~ars old) Severe cas~. Notl" ocular discharge.

Corneal ulcers (Figs 6.20-6.34) The corneal ulcer is common, usually unilateral, the appearance varying considerably according to the causc and stage of the ulcer. It is inVAriably painful And acromp.'lnicd by blepharosp.lsm and lacrimation. Diagnosis can be confirmed by s taining with fluorescein to show areas of denuded epithelium (Fig 6.20) and Rose Bengal to show areas of devita li:t..ed epi thelium (Fig 6.20. Causes include trauma, including selfinflicted llnd that due to eyelid abnormalities (supernumera ry eyel. thermal ilnd chemical burns, immune-med iated, facial paralysis and forms of exposure keratitis and absence of the protective tear film; also infections with b.lcteria, viruses and fungal elements. 111e appeara nce of the cornea l ulcer is dependent upon size, depth and time, varying from a faint opacity (oedema) to a denr, centra l, usually circular, deep Ilnd non-stfli ning keratocoele. Vascularization is usuo l, except in the indolent ulcer (recurrent epithelial erosion, Fig 6.22). If severe or of some standi ng, an associalt.>d uveitis, with hypopyon (Figs 6.27-6.28) and hyphaema (Fig 6.29) will be present. Pa in is variable, fro m mild to severe, particularly when uveitis is present.

Fig. 6.17 Fungal kl!ratitis marl!, 12 years old) Large Cl!ntral deep area of ulceration with furrowing.

Fig.6.1t1 Infl!ctiou5 bovine keratoconjunctivitis (Friesian calf) NOlI! cornl!al opaci ty due to oedema, vascular fr inge and mild conjunctival congestion,

Keratoconjunctivitis sicca (KeS) (Figs 6.35-6.44) KCS is nol primarily a kera litis but a defi ciency of the pre-ocula r tear film (aqueous portion), although it usually presents as a keratitis with a copious, tacky (Fig 6.37), purulent-like, d ischarge ad herent to the cornea (Fig 6.38) and oft en present in the con-junctival fornices (Fig 6.39). Severity varies from mild (Fig 6.35) to severe (Fig 6.36). Ulceration is unusual but when present is often decp .1nd ci rcular and w ith vascu larization (Fig 6.41 ). Pigmenta tion is

Keratoconjunctivitis sicc" (KCS) 53

Fig. 6. 19 1 keratoconjunctivitis (Friesian calf) Note central opaque area with vascularization following a previous ulcer in this position. Peripheral cornl!a now clear.

Fig. 6.20 recurrent corn l!al erosion showing area of denuded epithelium stainl!d with fluorl! scein.

common in chronic cases (Fig 6.42) and a con-junctival component is always present KCS of va rious causes is a common eye condition in the dog; most cases are immune-mediated and classically occurring in the UK in the middle-aged , often female, West Highland White Terrier. Othe r causes are systcmic disease (amine d is temper), metabolic disease (hyperthyroidism), surgical, tra umatic, neu-rogenic (oft en unilate ral and accompanied by a d ry nose) and idiopathic. An importan t group are due to lacrimotoxic drugs e .g. sulphas,., lazinc (Fig 6.43) and recently a congenita l fo rm of KCS (Fig 6.44), together

COfne~

Fig. 6.21 Corneal",,,, recurrent corneal erosion stained with Rose Bengal to show large area of devitalized epithelium surrounding the actual uker.

Fig. 6.22 Cornu! ulttr , 7 years I Rteurrent corneal erosion case. Note mild corneal oedema of the ukerated area and the epithelium at the edge of the ulcer. An early case, but see also Fig. 6.11 .

Fig. 6.23 Corneal ulcer COSH cat, young adult) Superficial dendritic ulcers in acu te feline herpesvirus-l infection.

Fig. 6.24 Corneal ulcer Ulceration and subsequent vascularization in a case of facial paralysis.

ulce:r (Pug, 8 months old) The: coagulase: or me:lting ulce:r. Note: the: stromal involvc:me:nt and dc:are:r cc:ntral portion indicating vc:ry thin rc:maining corne:a, toge:the:r with markc:d cornc:al oc:de:ma of the: re:maining non-ulce:rate:d corne:a.

Fig. 6. 26 Corne:al ulcer (Hunter-type. 7 ye:ars old) Coagulase or melting ulcer. Note the gelatinous discharge over the lower lid and adht:rt:nt to tht: eye:lashes; considerable pain.

Keratoconjunctiyitls siC(;! iKCSj 55

Fig. 6.27 Corneal ulcer Oe:ep ulcer and iritis. Note the hypol!ton and the mild miosis.

Fig. 6.28 Corneal ulttr Oee:p ulttr and note the dense hypopyon and corneal vascularization.

56 Cornea

1Jlc~ r Not~ th~ hypopyon and hy~ha~ma in this cas~.

fig. 6.30 Corn~al ul~r Not~ th~ corn~ilt o~d~ma. small cI~ar circular k~ratoco~l~ and vascularization in th~ low~r cI~ar cornea.

Fig. 6.3 1 Corn~al ul~r larg~ k~ratocode surrounding granulation tissu~ and vascularization.

Fig. 6.32 Corn~at ulcer Small de~p ulc~r with cl~ar k~ratoco~le; in this region the epith~lium and stroma have been lost leavIng only Descemet's m~m brane and endothelium. Note also the vascular fringe and oedema of the surrounding stromal region.

I I ul~r Ruptur~d keratocoel~ with cl~ar~r c~ntral ar~a and surrounding corn~al oedema and vascular fringe. Note the shallow ant~rior chamber due to early anterior synechiae and loss of aqueous,

ul~r D~ep

ulceration with surrounding granulation tissue, oedema and vascularization.

ICeralOCOlljl,lnctiviti5 sicc~ (ICCS) 57

6.35 Keratoconjunctivitis sicca Highland White Terr ier, male, 3 years old) Early case with mucoid filaments on the cornea but no corneal pathology. The Schirmer tear test result was zero.

Fig. 6.36 Keratoconjunctivitis sicta T~rri~r, f~mal~. 4 years old) Advanced case of xerosis..

58 Cornea

Fig. 6.37 Kerato

fig. 6.41 Ktratoconjunctivitis 5io::a Highland White Terrier, female, 7 years old) Typical deep circular ulttr and keratocoele.

Fig. 6.42 Keratoconjunctivitis ';0" White Terrier, male, 5 years old) longw~itand ing case with secondary pigmentary ktratitis.

Kera toconjunctivitis sic:ta (KCSI 59

I I (Yorkshire Ttrrier, fema le, 2 years Iatrogenic case following sulphasalazine thtrapy for colitis.

Fig. 6.44 Keratoconjunctivitis i I Charles Spaniel, female, 16 wetks old) Congenital case associattd with skin condition.

60 COfn~a

with a skin disease (ichthyosis), has been described. KCS is usually bilateral bu t the two eyes may differ in the degree of severi ty and the condition is more uncomfortable than pai nful. Diagnosis is b.1.sed on the clinica l signs, together with a Sc.hirnler tear test 1 to measure tear secretion.

Corneal oedema (Figs 6.45-6.55) Corneal oedema is not a specific d isease but results from a fa ilure of the corneal pump mechanism, usually damage to the corneal epi thelium or, more commonly, the endothelium. Corneal oedema is an opacity, and presents as such, varying in density and is either focal or diffuse. TIlcre are a number of known ca uSt.'S, including trauma and inheritance,

Fig. 6.45 Corneal oedema (Airedale Terrier, 4 months old) Dense corneal oedema and vascular fringe occurring 12 days after vaccination with lille attenuated canine adenollirustype- 1 vaccine ; referred to as 'blue eye:

but many cases nrc idiopathic. It is, together with vasculariza tion and pigmentation, one of the classic responses of the cornea to insult

Corneal oedema may affect one or both eyes and to the same or differing dcgtcw. Al though the eye may appear 'blind ', there is little or no effect on vision. Other parts of the eye may well be involved with corneal oedema, including uveitis (Fig 6.45), lens luxation (Fig 6.53) and glaucoma (Fig 6.54.). Corneal oedema is not pa inful, bul in severe cases may develop in to a bu llous keratopalhy in which disruption of the bullae does cause pain (Figs 6.46--6.4n. Corneal oedema leads to a thickened cornea and sometimes to an obvious keratoconus (F;g 6.49).

Fig, 6.46 Corneal oedema Dense: oedema, together with a few clear bullae.

Fig. 6.47 Corn~al oed~ma Severe bullous keratopathy.

Fig. 6.48 oedema 6 months old) Long~standing case with corneal pigml::ntatlon. Another post-vaccination case (sl::e Fig. 6.45).

COfne~ 1 O(dcm~ fil

Fig. 6.49 Corn~a l oedema Slit-lamp photograph showing thickening of the: ce:ntral corne:a due: to the: oedema and k~ ra toconus.

Fig. 6.50 Corn~al o~dema (English Spring~r Spani~ l, 9 years old) Note the typical mottled appearance of the oedema in th~ central region, tog~ther with one or two small bullae. This is a case of endothelial dystrophy presenting as corneal ot:dema in this breed.

62 Cornu

Fig. 6.51 Corneal otdema (Chihuahua, 5 years old) A bilateral case with severe oedema again due to an inherited torneal endothelial dystrophy.

Fig. 6.52 Corneal oedema (Friesian calf) Bilateral condition inherited in this breed. Again, note an associated keratoconus.

Fig. 6.53 Corneal oedema 5 years old) Central Of subcentral corneal opacity associated with primary lens luxation. The anteriorly dislocated lens is pushed against the corneal endothelium causing the oedema. If the It:'ns later becomes dislocated into tht:' posterior segmt:'nt. this corneal opacity will persist.

Fig. 6.54 Corneal oedema i i 5 years old) Diffuse oedema associated with primary glaucoma. Note also the slight conjunctival oedema (chemosis).

Lipid keratopathies (Figs 6.56-6.62) Lipid deposition in the cornea, sometimes in-correctly referred to as a corneal dystrophy (col'TeCtiy dystrophy is a primary inherited bilateral condition affecting any p."Irt of the cornea and not associated with inflammation), occurs in a number of not fully understood conditions which present as a corneal opacity.

The commonest {oml of lipid keratopathy, often referred to as corneal lipidosis (Figs 6.56 659), is a usually bilatera l, not a lways symmetrical il nd some-times starting in only one eye, cen tral or paracentral, subepithelial (non-staining with fluorescein), silver-grey metallic oval opacity. It is progressive to a stage but not further ilnd sometimes regressive, and not associiltoo wi th ilny innarmUlltion or pilin. It usually occurs in young ildults and w ith il definit e breed incidence (Roug h Collie, Shetland Sheepdog, Cavalier King C1m rlL'S Spa niel, Afghan and Siberian Husky) and is sometimes related to the oestral cycle, although it illse occurs in the ma le.

Fig. 6.55 CornC!al oC!dC!ma marC!, 7 yC!ars old) Bilat-=ral and asymmwical, partial ()(dC!ma in a Y~rtical strilX and of unknown a~tiology. This distribution of OI:d~ma has only bt~n st:~n in th~ ho~.

Lipid ~~falopalhies 63

Fig. 6.56 Lipid k~ratopathy I II i i Collie, 3 years old) Typical appC!arancC!, bilateral condition, approlCimatC!ly symmetrical, cC!ntral cornC!a. NotC! thC! pC!rfC!ct corn~al rdkction indicating normal oYC!rlying C!pithC!lium.

(cornC!al lipidosis) (Caval iC!r King CharlC!s SpaniC!I, f~male. 3 y~ars old) Typical agC!, brC!C!d and svc. Notc! th~ crystallinC! apjl('arancC! of thc! lesion.

Cornea

Fig. 6.58 lipid keratopathy (corneal II i i (Cavalier King Charles Spaniel. female, 3 years old) larger and less dense lesion than that shown in the previous figure.

Fig. 6.59 Upid keratopathy (corneal lipidosis) (Siberian Husky. 3 years old) Another typical breed.

Fig. 6.60 lipid keratopathy (corneal lipidosis) (German Shepherd Dog) A case of primary hypothyroidism. Note the perfect corneal reflection. the incomplete arcus superiorly and a clear band of cornea immediately inside th e limbus.

Fig. 6.61 Ullid keratopathy (lipid and calcareous degeneration) (Golden Retriever. 3 years old) Perilimbal lesion with epithelial involvement and vascularization.

Arcus tipoidcs (Fig 6.60) is another bil

66 Cornea

SfqUfstrum Sfqutstrum surroundfd by granulation tissue: and much cornfal vascularization. Note also the prominence of the nictitating membrane dUf to globe rftraction due: to pain and again thf black discharge on the upper lid.

Trauma and foreign bodies {Figs 6.66- 6.70} Corneal (oreign bodies are commo n in all the domestic species and vary cons iderably in their nature. Corneal reaction. usually following a sudden onset. varies according to the size. dcpth and nature of the fo reign body: p.1in, blepharospasm or a dosed eye. The ocular discha rge va ries from d ear lacrimation to purulent.

Com cal trn uma is also common in the horse. dog and cat, particularly in the fomler with its large prominent cyes. Trnuma varies from blunt trauma with corncal oedema to a penetra ting injury with loss of aqueous, h"emorrhagc which may be profuse, loss of anterior chamber and prolapse of iris. Pain may be severe.

Corne"l (lbscess (Fig 6.70) ilppears OlS a small foc,,1 non-painful raised swelling, Olssociated with vOlscularization. and usunlly adjacent to the limbus.

Fig. 6.65 Corneal sequtstrum (Ptrsian cat, 4 yfars old) Medium-sized sequestrum with vascularization. Both eyes of this cat were involved.

Fig. 6.66 Corneal foreign body cat. 2 years Small thorn foreign body, recent case. This cat presented with acute blepharospasm.

. 6.67 Corneal foreign body (Border Terrier, 7 years Leaf foreign body of 3 weeks' duration. Note the

profound corneal reaction to this foreign body of organic material.

Fig. 6.68 Corneal trauma Shepherd Dog. 10 weeks old) Ptnetrating corneal wound with coagulated aqueous and prolapse of iris t issue but no haemorrhage in this case. Of recent origin. This injury was due to a cat scratch - a typical history.

Truuma and fore ign bodi~ 67

Fig. 6.69 Corneal trauma King Charles Spaniel, 3 years old) Corneal rupture with iris prolapse plugging the wound. Note the surrounding corneal oedema and vascular fringe.

Fig. 6.70 Corneal abscess (English Springer Spaniel, 3 years old) Note the raised appearance of the lesion which is subepithelial and the vascularization. In this case the lesion was non painful, the dog prestnting with a focal area of corneal opaci ty.

68 Cornc~

Neoplasia (Figs 6.71-6.72) Corneal neoplasia in the dog ond cat is ~ but squamous cell carcinoma in the horse is an important condiUon. The appearance is of a pinkish grey granular tumour spreading across the eye and usua lly associa ted with a slight ocular discharge and a degree of blepharosp.-lsm.

"",,,II tumour (Hunt~r-typ~. 10 y~ars old) Squamous c~1I cardnoma of corn~a and limbus. Th~ nictitating m~mbran~ of this hors~ had b~~n r~moved, probablv also du~ to a squamous c~1I cardnoma.

Fig. 6.72 Corneal tumour 9 vears Squamous c~U carcinoma. Note the typical gr~vish appearanct of th~ tumour.

Congenital anomalies (Figs 6.73-6.74) Microcornea is usua lly associated with microph-thalmos and multiple congenital anomalies (Fig 1.12.)

Epibu lbar dermoids (Figs 6.73-6.74) occur on the rornea, particularly in the dog. They are usually pigmen ted and contain hair and cause surpris ingly little discomfort.

Fig. 6.73 Corneal d~rmoid Shepherd Dog, 3 months old) Pi9m~nt~d ~piburbar d~rmoid containing hair but apparently causing little discomfort

6.14 Corneal d~rmoid (German Sheph~rd Dog, 3 months old) Fleshv and hair contaming. Epibulbar dermoids are typicallv seen in this br~~d (s~e also Figs 2.49-2.50 and 5.20-5.22).

Chapter

Uveal Tract

Introduction The uveal tract consists of iris and ciliary body, together with the choroid which is bt."'S1 included in the fundus (Chapter 11). The liven] tract is imporlnnt in veteri nary oph thalmology in dog, cat and horse; it may prcsl!nl os a uniocu lar or binoculnr eye d iscnsc or condition and may indicate local (ocular) or systemic disease (Table 7.1). Diagnosis eiln be difficult and aetiology is often obscure (Table 7.2). The uveal tract is prone to trauma and also exhibits several congenital, some hereditary, cond itions in addition to cysts and tumours.

The colour of the iris varies considerably and is associated with Co.,\ colour. Most irides in the dog and horse are shades of brown and in thecal yellow or gold and often metallic. However, pale blue irides, ei ther pilrtial or 101011, are not uncommon in all Ihree species ilnd usua lly are accompanied by areas of suba lbinism in the fundus. Furthemlore, a change in iris colour may denote disease. The pupil shape also differs considerably in the three species and may change with disc .. se.

Table 7.2 _ Uye1t15: differential dlagnods

Pupil Intr3ClCu iar pressure

Uveitis Constr ic~ ~

Glaucoma Dilates r Conjunctivitis No changc No change

Table 7.1 - Tht red t~

Unilateral or bilateral Acute or chroniC Local ocular disease or systcm1c with pyrexia (bilateral) 1. Uveitis

Photophobia 2. Glaucoma

Breed.speciOc for prlmQry, 50me secondary cases Unilateral at first presentation

J. Conjunctiyitls Primary or, more commonly, sccondarv (oculi,., or systemic) Traumatic (subconjunctival haemorrhage)

4. Epls.cleritr$/s.clcritis Uncommon, usually no pain

5. Keratitis Induding COfneal ulCtr (palnl

6. Ortrit;ll distast Enophthalmltl5 Panophthalmitis Retrobulbar [Inflammation, neopLUla) Prolapse

Pain Vision .. Minor effect

.. < Blind < No change

Olschargc

Lacrimation Lacrimation Serous-p.urulent

10 UytaJ Tract

Clinical signs of anterior uveitis (iritis or iridocyclitis) n'e clinical signs vary with the cause, severi ty and species but are not specHic to the aetiology: Pain - may be considerable and presenting

w ith the us ual triad of lacrimation, blepharospasm and photophobia.

Miosis (Figs 7.1-7.3, 7.5). InlraocuJar pressure low. Iris colour - in the brown iris the colour is

duller and darker, particularly evident in the chronic case (Fig 7.2) and a useful clinical sign 10 indicate a previous iritis; in the yellow (cat) or blue iris the congested blood vessels are obvious (Figs 7.11 and 7.13), knO\vn as ru beosis iridis.

Flare (Figs 7.7, 7.11, 7.29), hypopyon (Fig 7.1O), hyphaema (Figs 7.9, 7.12-7.13)-cells (white a nd red blood cells) in the anterior chamber.

Conjunctival and episcleral hyperaemia -particularly in the ciliary region (ciliary flush) (Fig 7.1).

Synechia fo rmation - common ly posterior w ith adhesion to anterior lens ca psule producing irregular pupil shapes (Figs 7.15-7.19); occasionally anterior (Fig 7.28) lead ing to secondary glaucoma.

Chemosis a nd corneal oedema (Figs 7.5--7.6 and 7.24-7.25).

Vascularization - usually as a fringe in the periphera l cornea (Figs 7.5-7.6); occasionally blood vessels extending onto the anterior lens C&lpsu le.

Vitreous - cloudy and turbid. Chorioretinitis - see Chapter 11.

Sequelae Cataract (Figs 7.23, 7.26) - by far the most

common, usually anterior capsular, cortical, sometimes total. Mayor may not be associated with posterior synechiae.

Fig. 7.1 Irit is (Cavalitr King Charlts Spanitl. 10 ytars old) Acutt traumatic iritis. Nott tht marktd miosis and tht conjunctivallnjtction.

,t,,, Poodlt. 10 ytars iritis. Nott tht darktntd iris, pigmtnt on anttrior ltns capsult togtthtr with small posttrior syntchiat, and miosis.

Fig. 7.3 Iritis , 6 years recurrent uveitis. Note occlusion of pupil due to miosis and posterior synechiae and dull dark Iris.

Fig. 7.4 Iritis (Miniature Poodle, 6 years old) Vascular corneal fringe, together with haemorrhage on the lens and cataract Note the herniated uveal pigment around the pupil edge.

~qutlat 71

Fig. 7.5 Iritis (Weimaraner, 3 months I Note miosis, fine vascular fringe from superior limbus, marked corneal oedema and keratoconus. See also Figs 6.45-6.48 of corneal oedema and uveitis associated with canine viral hepatitis and vaccination.

Fig. 7.6 Iri tis Equine recurrent "" vascularization from the superior limbus and mild corneal oedema.

72 Uveal Tru!

Fig. 7.7 Iritis (Airedale Terrier, 2 years Acute iritis, showing plastic endothelial deposit and flare. Idiopathic case.

Fig.7.B Iritis cat, 15 years tOlCoplasmosis showing ker.ltitis predpitata (KP).

Fig. 7.9 Iritis (Crossbred dog, 14 years diffuse cloud of haemorrhage and dull iris. Idiopathic case.

Fig. 7.10 Iritis cat, 10 months I of white cells obscuring the pupil. Another tOlCoplasmosis caS

Fig. 7. 11 Iritis Rubeosis lridis and flare (visible in the pupillary area).

Fig. 7.12 Irit is (DSH ca t, 1 yur 1 Hyphaema in a cat with feline infectious ~ritonitis.

Sequelae 73

Fig. 7.13 Iritis (DSH cat, B years I Hyphaema and rubeosis iridis. A further case of toxoplasmosis and note thr diffrrence in presenting signs between Figs 7.B, 7.10 and 7.13.

Fig. 7.14 Irit is (Crossbred dog, 4 years to trauma showing swollen iris. miosis and haemorrhage.

74 Uvtal Tract

Fig. 7.15 Iritis i old) PDstr:rior synechiar: and r:cctnlric pupil.

Fig. 7.16 Iritis (Miniaturr: Poodlr:. 10 yr:ars old) Postr:rior synr:chiar: and cataract

Fig. 7.17 Iritis Russr:1I Tr:rrir:r. 6 yr:ars Postr:rior synr:chiar: and sr:condary 9laucoma.

Fig. 7.18 Iritis (8ordr:r Collie. 9 years old) Iris bombi due to postr:rior synechiae and st:condary glaucoma.

irrtgularity of pupil. Idiopathic caSt.

Fig. 7.20 Iritis (OSH cat. 18 months old) Iris rests (posttrior syntchiad.

Stqutlat 75

Fig. 7.21 Irit is (Thoroughbrt d) Iris rtsts. Idiopathic case.

Fig. 7.22 Iritis Equint recurrent uvtitis. Posterior syntchiat producing irregularity of the pupil.

76 U~~I Tract

Fig. 7.23 Iritis (Thoroughbred, 12 years old) Equine reC1Jrrent uveitis. Posterior synechiae and cataract

Fig. 7.24 I ii pony, 3 years I ,;;'" recurrent uveitis. Dull and faintly opaque cornea with mIOSIs.

Fig. 7.25 Iritis Shepherd Dog, 3 years old) Ehrlichiosis. Note the multiple haemorrhages on the iris and the corneal oedema.

7.26 Iritis (Akita. young adult) A case of Harada's disease. or Voght-Kayanaga-Harada (VKH). Note posterior synechiae and cataract.

Fig. 7.27 Ii i I uvt!il is in a diabt!tic dog. Note tht! irregulari ty of Iht! antt!rior It!ns capsule, tht! darkened iris and postt!rior synechiat!. St!t! also Fig 9.24.

Fig. 7.2B Trauma Ptnt!traling corneal injury I anterior synt!chiat! and ht!alt!d corneal scar with tint! vascularization.

S~quda~ 77

Fig. 7.29 Trauma Penetrating foreign body. flart! particularly evidt!nt in tht! pupil. miosis and herniation of postt!rior uvt!al pigmt!nt in the supt!rior part of the pupil.

7.30 Trauma (English Springt!r Spanit! l, 3 years old) Iris prola~ following a shot injury. Nott! tht! Sl,Ioconjunctival haemorrhagt!.

78 Uycal Tract

Fig. 7.31 Trauma young adult) ""';.; corn~allnjury with iris ha~morrhag~ .

Sequelae (continued from p. 70) Lens luxation. Gla ucoma (secondary) - uveitis commonly

precedes cases of g laucoma in the horse. Phthisis - the result of severe inflammation,

again us ually in the horse.

The causes of uveitis are m.lIlY and varied, and include trauma (Fig 7.14), renex (corneal ulcer), immune-mediated. lenS-induced , vira l, Rickettsial, bacteria l, fungal and parasitic. Uveitis may be u niocular or binocu lar and accompa nies several systemic diseases in the three species (Figs 7.8, 7.10, 7.12-7.13, 725-7.26). Many C.lses remain idiopathic .

Cysts (Figs 7.32- 7.38) Not uncommon in all three sJX.'Cies.

Neoplasia (Figs 7.41-7.54) Melolloma is the Illost common (particularly in grey horses), but also adenoma. adenocarcinoma, medulla-epithelioma and multicentric lymphosarcoma.

Congenital anomalies (Figs 7.55-7.67) Persistent pupillary membranes (Figs 7.59-7.67). Not uncommon in all three species and may cross part of the iris or the pupil or be attached to anterior lens capsu le or pos te rior cornea and present as opacities in these positions.

Colobomas (Figs 7.55-7.58) Occur in all species but are rare in the cal.

Fig. 7.32 Uv~al cysts ( Crossbr~d dog , 7 y~ar5 old) Two attach~d at pupillary margin and on~ fr~~ in ant~rior chamb~r. D~ns~ cysts.

Fig. 7.33 UvC!al cyst Iu.b" wallC!d cyst

Fig. 7.34 Uv~al cysts (labrador Retri~ver. 9 months old) Cataract and aS5OCiat~d cysts around the pupillary border followi ng uveitis.

Fig, 7.35 Uveal cyst (labrador i "'. Ruptu red cyst adherent to the posterior cornea.

Congenital anomalies 79

Fig. 7.36 Uveal cysts (DSH cat. 5 years old) Several fr~e cysts in th~ ant~rio r chamber.

Fig. 7.37 Uv~al cysts (Hu nter-typ~, 9 years old) Cysts attached to pupillary margin.

80 Uvul Tract

Fig. 7.38 Uveal cyst (Welsh pony. 7 years old. grey) Stromal cyst or iris hypoplasia. Typically occurs in the superior mid iris region in a heterochromic iris.

.7.39 Corpora nigra hyperplasia (Hunter- type. 13 years old) Note the complete obliteration of the centre part of the pupil. The other eye showed no abnormality and there was no further progression.

i 7.40 Corpora nigra trauma (Thoroughbred. 4 years old) Whiplash type injury resulting In tearing of the corpora nigra.

Fig. 7.41 Tumour (English Springer I Iris and ciliary body melanoma. Note the early distortion of the pupil and compare with the limbal melanoma lFigs 5.31-5.32).

Fig. 7.42 Tumour (Afghan Hound , 7 y~ars I

body m~lanoma. Not~ th~ large swelling with gross

distortion of the pupil.

Fig. 7.43 Tumour (Staffordshir~ 8ull 6 y~ars

old) Ciliary body adenocarcinoma. Note the unpigmented

pink mass in the anterior chamber with distortion of the

pupil.

Congenital anomafil!S 81

Fig. 7.44 7 years I

adenocarcinoma. Note the appearanc~ of the tumour

through the pupil.

Fig. 7.45 Tumour R~triever, 9 years

Ciliary body adenoma. Note the small haemorrhage on the anterior lens capsule and the appearance of the

tumour through the pupil.

82 Uye~1 Traet

Fig. 7.46 Tumour Springer Spaniel,S years old) Multicentric lymphosarcoma. Note the secondary glaucoma due to obliteration of the angle of filtration.

Fig. 7.47 i change of the anterior iris surface with no distortion of the pupil.

Fig. 7.48 Tumour (DSH cat, 9 years old) Diffuse iris melanoma with pigmentary deposits on the posterior cornea.

7.49 Tumour (DSH cat) Iris melanoma. Note the raised areas of iris and pupil distortion.

Fig. 7.50 Tumour (DSH cat. 1 ye:ars old) Iris me:lanoma. Note: the: pigme:nte:d mass appe:aring in the: pupil and the: incre:ase:d vascularization of the: iris on that side:.

:::U(D~S~H~cat, 16 ye:ars old) Multice:ntric lymphosarcoma. The: kidne:ys we:re also involve:d.

Fig. 7.52 Tumour lymphosarcoma.

Congenital anomalies 83

Fig. 7.53 Tumour {Pony. 13 ye:ars old. gre: Yl Iris me:lanoma. The: tumour is touching the: poste:rior cornea and producing an area of corneal oedema.

84 U~cill Tract

Fig. 7,54 Tumour (Pony, 7 years old, blue-eyed cream) Amelanotic melanoma.

Fig. 7.55 Coloboma (Min iature Poodle, S