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n general, the techniques of evaluating theavian eye are similar to those used in mam-mals. However, the small size of the eye incompanion birds and the striated sphincter

muscle of the avian iris necessitate modified proce-dures to visualize the posterior segment of the eye.

Each ophthalmologist has a particular pattern forophthalmic examination. The key to effective evalu-ation is to develop a logical, consistent use of thesame pattern of examination for each eye.

Before a bird is agitated by restraint, the eyes shouldbe evaluated from a distance, noting whether thebird will fixate on moving objects, whether both pu-pils are the same size and whether there are anyobvious abnormalities in the periorbital area (Figure26.1). Vision can be difficult to evaluate because birdscan feel slight air movements created by an ap-proaching hand. The detailed examination requiresadequate restraint, and a darkened room will calmthe bird and improve the illumination provided by afocal light source.

Many disease processes affect the external eye andperiorbita. Ocular discharge, conjunctival hyperemiaor periorbital swelling can be an indication of a pri-mary ocular disorder or may occur secondary to si-nusitis or facial dermatitis (see Chapter 24). Somelarger Psittaciformes may inflate a portion of theirperiorbital sinus as an aggressive gesture, creating atransient swelling in the periorbital region (Color26.7). This swelling should not be mistaken for peri-orbital disease. Collapse of the anterior chamber mayoccur in an otherwise normal eye following a periodof head restraint or lateral recumbency during anes-thesia. Normal anterior chamber depth is rapidlyregained.

Examination of the anterior segment can be per-formed with a bright pen light, a binocular loupe, anoperating microscope, an ophthalmoscope set on +20diopters or, ideally, a slit lamp (Figure 26.2). Keyfeatures to evaluate are the clarity of the cornea, theaqueous, the lens and the color and vascularizationof the iris. Aqueous flare, as seen in uveitis, can bedetected by looking for scattering of a slit light beamthat is passing through the anterior chamber (Colors26.25, 26.26). Pupillary light reflexes can be deter-mined, but because the avian iris is under consciouscontrol, rapid changes in pupil diameter according to

I C H A P T E R

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David Williams

the degree of alertness of the animal can make evalu-ation difficult.

Retinal examination is difficult in many birds be-cause of the small size of the eye and the lack ofresponse of the avian iris to conventional parasym-pathomimetic mydriatics. Mydriasis can be accom-plished by intracemeral injection of d-tubocurarineor by the frequent use of a freshly prepared topical 3mg/ml solution of crystalline d-tubocurarine in0.025% benzilonium chloride over a fifteen-minuteperiod.5,56 A more practical approach may be the topi-cal use of commercially available neuromuscularblocking agents commonly used for intravenous in-

jections. The most useful regime in raptors has beenfound to be vecuronium bromide solution (4 mg/ml)topically every five minutes for fifteen minutes (seeChapter 18).53

With or without mydriasis, the easiest way to viewthe fundus is to start with the direct ophthalmoscopeat the +20 dioptre setting, and with the instrumentclose to the bird’s eye, change the dioptre settinggradually back to zero. This will bring the pleatedpecten into view. It is then possible to focus on theavascular retina at the posterior of the eye. An indi-rect ophthalmoscope is excellent (Figure 26.3), al-though an expensive binocular all-pupil model isneeded if adequate mydriasis is not achieved. A 28 or40 dioptre lens is useful to obtain a good field of viewin the small avian eye. A 90 dioptre lens used with aslit-lamp provides excellent visualization of a largearea of the fundus.

Ancillary Tests for Evaluation of the Eye

Further testing can be used to confirm or refute thepresence of suspicious lesions detected by gross ob-servation. Corneal ulcerations can be detected bystaining with fluorescein dye. The Schirmer TearTests can be used on birds, although normal data forpsittacine birds have not been published. Conven-tional 6 mm-wide Schirmer tear test filter paperstrips have been found to be difficult to insert in thelower conjunctival sac of the smaller Psittaciformes;thus trimming these to 4 mm is more useful. Thisalso gives a higher reading of wetted strip length thanthe 6 mm-wide filter strips, with which the Schirmertear test results are rarely over 3 in clinically normal

FIG 26.1 Normal periocular area in a Grey-cheeked Parakeet. Theeye should be open with a bright, shiny appearance. The lidmargins should be evenly colored, dry and symmetrically shaped.

FIG 26.3 Indirect ophthalmoscopy in a cockatiel to evaluate thefundus. A 28 diopter lens is particularly useful but results in aninverted image that requires some practice to interpret (courtesyof David Willaims).

FIG 26.2 A slit lamp is ideal for examining the anterior segmentof the avian eye. The lamp can also be used to facilitate evaluationof oral and dermatologic lesions (courtesy of David Williams).

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birds. To date, Schirmer tear test readings have beenfound to be 8 ± 1.5 mm in the larger Psittaciformessuch as the African Grey Parrot, and 4.5 ± 1 mm insmaller species such as lories and conures.

The difference in tear production between species ispresumably related to the size of the orbit and lacri-mal gland tissue. These interspecies differencesmake it difficult to provide standard normal data forall Psittaciformes. With unilateral problems, com-parison between the affected and the unaffected eyemay be useful. A normal bird of the same species,ideally an enclosure mate, can also be used for com-parative purposes.

Tonometry is possible in birds, but little normal datahas been published. The simple indentation Schiotztonometer cannot be used in smaller birds because ofits large footplate, which covers the cornea and sclerain all but the largest avian species. However, theportable Tonopen applanation tonometer is ideal foruse in birds. One study indicates that this instru-ment provided reproducible readings in birds withcorneal diameters over 9 mm. Some readings in birdswith corneal diameters as small as 5 mm were reli-able.40 This tonometric examination of 275 birds (39species) showed intraocular pressures in normal eyesof between 9.2 and 16.3 mmHg. Among 14 species ofpsittacine birds, values were found to be 14.4 ± 4.2mmHg with a sample size of 74 birds.

Avian periorbital and external eye disease is frequentlyassociated with infectious agents. A consistent tech-nique for sample collection should be used to increasethe validity of the sample. The best diagnostic bacterio-logic samples can be obtained by inserting a sterileswab moistened in transport medium into the upperconjunctival fornix and rubbing it from side to side twoor three times. The upper fornix is the preferred site forcollecting culture samples because there is less con-tamination from environmental organisms than in thelower fornix. Conjunctival scrapings can be stainedwith a modified Wright’s stain for general cytology. AGiemsa stain can be used to detect chlamydial elemen-tary bodies (see Chapters 10, 34).14

Anatomy of the Eye

An understanding of the anatomy of the avian eye(Figures 26.4-26.7) and how it differs from the mam-malian eye is vital when differentiating between thenormal and abnormal.24,46,52,68,77

As an overview, the avian eyelids are mobile, thelower more so than the upper. The meibomian glandsare absent, but a lacrimal gland (varying in sizebetween species) is present, inferior and lateral tothe globe. The Harderian gland acts as a secondlacrimal gland at the base of the nictitating mem-brane (Figure 26.5). The nictitating membrane ac-tively moves over the cornea during blinking and inthe menace response (Color 26.1). It has an unusualmuscular arrangement; it is drawn across the eye bythe pyramidal muscle originating in the posteriorsclera and loops over the optic nerve through a slingformed by the bursalis muscle (quadratus muscle.)Inferior and superior nasolacrimal puncta at the me-dial canthus drain lacrimal secretions into the nasalcavity (Color 26.2).

The orbit is open, but, because the globe occupies thevast majority of the space, the rectus and obliquemuscles are not well developed, and torsional move-ments of the globe are limited in many species tobetween two and five degrees. A key point in theanatomy of the avian orbit is the close proximity ofthe tightly packed orbit with the infraorbital diver-ticulum of the infraorbital sinus (Figure 26.5). Si-nusitis and enlargement of this diverticulum will

FIG 26.4 Relative size of the globe to the skull.

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therefore lead to periorbital or orbital compressionand signs of periorbital swelling, conjunctivitis andsometimes intraocular disease (Color 26.16).

In most birds, including Psittaciformes, the globe isanterio-posteriorly flattened, with a hemisphericalposterior segment. It is rounded in some diurnalbirds and tubular in owls (Figure 26.6). The scleraimmediately posterior to the cornea contains scleralossicles, and through its full circumference, thesclera has a support of hyaline cartilage (Figure26.7). The avian cornea is similar to that of mammalsexcept that it is considerably thinner, and unlikemammals, it has a Bowman’s layer. The thickness ofthe cornea varies depending on the size of the bird.The anterior segment is relatively shallow comparedwith the posterior segment, with some anatomic dif-ferences noted between species. Owls have an unusu-ally deep anterior chamber (Color 26.21).

The iris is thin and contains striated dilator andconstrictor muscles. Varying chromatophores createthe different iris colors noted with age, gender andspecies of some birds. In some white cockatoo species,for example, the iris is dark brown in the adult male

and reddish pink in the adult female. Immaturecockatoos of both genders have black irides. In theMoluccan Cockatoo, however, the male has a blackiris and the female has a dark brown iris, and in mostblack cockatoo species and in the Goffin’s Cockatoo,there is no gender difference in eye color. Young Blueand Gold Macaws have a dark iris that lightens inthe first two to three years and then turns yellow asthe bird ages. African Grey Parrots have darkmuddy-grey irides as young birds, which turn yel-lowish-grey and then silver as they mature.

Pupillary light reflexes do occur in birds but theirinterpretation is complicated by the fact that voluntaryconstriction and dilation of the pupil is possible, evenin the absence of retinal stimulation. Clinically, thecomplete separation of the optic nerves prevents theelicitation of a consensual pupillary light reflex. Theiridocorneal angle is well developed in all birds anddrains the aqueous fluid, as in mammals. The lens issoft and is almost spherical in nocturnal birds, or has aflattened anterior face in diurnal species includingcompanion birds. An annular pad lies under the lenscapsule in the equatorial region, and can be separatedfrom the center of the lens during cataract surgery.

FIG 26.5 a) Anterior and b) Posterior view of the avian globe. 1) Nictitating membrane 2) M. lateral rectus 3) lacrimal gland 4) gland ofnictitating membrane 5) M. dorsal rectus 6) M. dorsal oblique 7) M. medial rectus 8) M. ventral oblique 9) M. pyramidalis 10) M. ventralrectus 11) optic nerve and 12) M. quadratus (modified from Martin46).


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The color of the fundus varies considerably amongspecies; however, all species have a pecten, a comb-like black or brown projection of choroidal tissue thatextends into the vitreous (Color 26.35). Recent workhas shown that small, regular torsional movementsof the eye sweep the pecten through the relativelyfluid vitreous. Blood vessels in the pecten disperse aserum filtrate that extends to the peripheral retina.62

The pecten is thought to provide oxygen and nutri-ents to the inner portion of the retina. Most species,including Psittaciformes and Passeriformes, have in-distinct fovea. Many raptors have one and some diur-nal raptors and hummingbirds have two foveae. Ma-caws have a particularly distinct foveal area that canbe evaluated fundoscopically. It is suggested that inbi-foveate birds, one fovea serves for near vision andthe other accommodates long-range vision. Birds candistinguish colors and in most cases have excellentvisual acuity. Because a bird’s sight is so importantbehaviorally, it is critical that ophthalmologic prob-lems are accurately diagnosed and rapidly resolved.

Ophthalmic Disorders

Lids and Periorbita

One of the most common ocular presentations inlarge psittacine birds is periorbital disease secondaryto upper respiratory infection, particularly chronicrhinitis and sinusitis (Figure 26.8) (see Chapter 22).As stated above, the close proximity of the infraorbi-tal sinus to the orbit predisposes it to physical dis-placement when the sinus diverticulum is enlarged.In some cases, cellulitis or abscessation occur fromspread of organisms from the sinus cavity. Antibioticsalone are rarely efficacious in these cases; flushingthe sinus and, in some cases, more aggressive surgi-cal debridement is required (see Chapter 41).

FIG 26.6 a) In diurnal birds, like this chickadee and most companion birds, the lens has a flattened anterior surface, whereas b) in nocturalbirds, like this Great Horned Owl, the lens is almost spherical. 1) pecten 2) fovea (modified from Martin46)


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PoxvirusAvian poxvirus may cause lesions in or around theeyes in a number of species (see Chapter 32). Theinitial changes include a mild, predominantly unilat-eral blepharitis with eyelid edema and serous dis-charge starting about 10 to 14 days post-infection

(Color 26.8). As the disease progresses, ulcerativelesions on the lid margins and at the medial or lateralcanthus develop; these can become secondarily in-fected, giving rise to a mucopurulent discharge andtransient ankyloblepharon (Color 26.9). The lids be-

FIG 26.8 An emu (left) was presented with a history of chronic sinusitis. A serous to mucoid oculonasal discharge was noted on physicalexamination. The sinus was retracted into the skull (“sunken sinus syndrome”). This condition has been most frequently reported in macawsbut may also occur with sinusitis in other avian species. Antibiotics were curative (see Chapter 22). A normal emu (right) is shown forcomparison (courtesy of Tom Tully).

FIG 26.7 Three-dimensional representation of the avian eye; enlarged view of the interior of the eye.

1) cornea2) lens3) iris4) scleral ossicle5) ora serrata6) vitreous chamber7) optic nerve8) pecten9) retina10) choroid11) sclera12) ciliary folds13) equator14) ciliary body

15) scleral venous sinus16) conjunctival ring17) trabecular reticulum18) anterior chamber19) lens capsule20) posterior chamber21) lens vesicle22) zonular fibers23) ciliary process24) sclera25) limbus


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come sealed shut with a caseous plug or with drycrusty scabs, which fall off within two weeks.50

Clinical lesions provide a tentative diagnosis. Aninfection can be confirmed through histopathologicidentification of eosinophilic intracytoplasmic inclu-sion bodies (Bollinger bodies) in scabs or scrapings ofperiocular ulcers.27,34

Poxvirus infections may cause keratitis and, lesscommonly, anterior uveitis. The keratitis can be mildwith corneal clouding or severe with ulceration thatprogresses to panophthalmitis and rupture of theglobe. Keratitis may lead to permanent corneal lidscarring. Cicatricial changes in the lid margins canlead to entropion, ankyloblepharon or deformities ofthe lid edge, resulting in keratitis from corneal abra-sion or environmental exposure. These patients mayneed corrective surgery (lid retraction) or can beplaced on life-long therapy with ocular lubricants.

Many affected psittacine birds, particularly Ama-zons, pionus parrots and mynah birds, have residualproblems that cause more important pathology thanthe primary ocular and periocular lesions. In onestudy, 46% of the Amazon parrots and pionus parrotswith poxvirus had post-infection ocular abnormali-ties.35 Eyelid and corneal lesions are most severe ifpoxvirus lesions are secondarily infected with bacte-ria or fungus. Treatment of poxvirus lesions shouldinclude topical antibiotic ophthalmic ointments toreduce the incidence of these sequelae. Systemic an-tibiotics may also be required in severely affectedbirds. Early eye lesions should be flushed with diluteantiseptic solutions. Once scabs have formed theyshould not be removed. It may be beneficial to softenscabs with hot or cold compresses soaked in nonirri-tating baby shampoo. It has been reported that pro-phylactic vitamin A supplementation of exposedbirds decreases the severity of infection36 (see Chap-ter 18). The importance of subclinical hypovitami-nosis A in the progression of the disease has not beendetermined.

Hypovitaminosis AHypovitaminosis A is less prevalent today than adecade ago; however, it may still be seen as a compli-cating factor in ocular diseases. Xerophthalmia issaid to be the classic sign of hypovitaminosis A inmany avian species, but the most common ocularchange in psittacine birds is mild periorbital andconjunctival swelling with some discharge (Color26.14). These signs can be subtle. Hypovitaminosis A

should be considered in cases of unexplained oculardischarge or swelling.

Nasal discharge, sneezing, crusted nares, dry oralmembranes and palatine and choanal abscesses arehighly suggestive of primary hypovitaminosis A, par-ticularly in Amazon parrots. Response to injectablevitamin A or oral beta carotene supplementation sug-gests the involvement of a deficiency in the diseaseprocess.42,63

Lovebird Eye DiseaseA severe and often fatal systemic disease with per-iocular lesions as the presenting sign has been re-ported in lovebirds. Generalized depression is accom-panied by blepharitis and serous ocular discharge,followed by hyperemia and edema of the periorbitawith a mucopurulent ocular discharge. Affected birdsare often attacked by enclosure mates and usuallydie within a few days of the onset of ocular signs. Thedisease is most commonly seen in the Peach-facedmutations, and it is in these birds that the lesions aremost severe.

No definitive isolation of an infectious agent has beenachieved, but an adenovirus-like particle has beendemonstrated in renal tissue by electron microscopy.Conjunctival inclusions have been found in someaffected birds.32,36 The histologic lesions reported inone case included proliferative inflammatory reac-tion of the subconjunctival tissue with lymphoid cellinfiltration and concurrent atrophic changes in con-junctival epithelium. Conjunctival edema with mini-mal cellular infiltrates were characteristic in othercases. The disease occurs most frequently immedi-ately after shipping or introduction into a new aviary,suggesting that stress may be involved in initiatingpathologic changes. Symptomatic therapy that in-cludes isolation of affected birds in a stress-free envi-ronment and administration of antibiotics has beensuggested.

CL INICAL APPL ICATIONSSinusitis frequently causes ocular disease because of theclose proximity of the infraorbital sinuses and the globe.

Hypovitaminosis A may cause mild periorbital swelling.

Lacrimal sac masses present as mobile swellings anterio-ventral to the medial canthus.

Pupillary light reflexes are difficult to interpret becausebirds can voluntarily constrict and dilate the pupil.


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Color 26.1A three-month-old Blue and Gold Macawwas presented with a two-week history ofserous nasal discharge. Note the accumula-tion of debris on the feathers of the face. Thenictitating membrane, which moves overthe cornea during blinking and in the men-ace response, is normal. This bird’s rhinitiswas caused by exposure to cigarette smoke.

Color 26.2An Umbrella Cockatoo was presented witha two-month history of unilateral dis-charge. Note the moist, discolored featherson the face. The nasolacrimal duct in thisbird was occluded and was opened by re-peated flushing with warm, sterile saline.

Color 26.3Depression and hyperemia of the face andeyelids in a gallinaceous bird with sinusitisand pneumonia.

Color 26.4Periocular dermatitis in an Amazon parrotfrom southern Florida. These lesions, fre-quently encountered in birds in outdooraviaries, are believed to be caused by bitinginsects.

Color 26.5a) Gross proliferative lesions caused byKnemidokoptes sp. infection in a budgeri-

gar. b) Knemidocoptes spp. are most fre-quently associated with beak and cere le-sions but can also cause lesions in the peri-orbital tissues (courtesy of the Unit forContinuing Veterinary Education in Lon-don and John E. Cooper).

Color 26.6A mature cockatiel was presented for diar-rhea and weight loss of five days’ duration.The bird had partial paresis of the eyelid,mild conjunctivitis and was unable to bite.Partially hulled seeds were common in thebottom of the enclosure. Giardia spp. weredetected in a fecal smear. The bird re-sponded to treatment with metronidazoleand vitamin E.

Color 26.7An Amazon parrot with a transient perior-bital sinus inflation. This inflation is be-lieved to be secondary to stressful eventsand is not indicative of a pathologic prob-lem.

Color 26.8Scarring of the palpebral margin secondaryto a poxvirus infection (courtesy of DavidWilliams).

Color 26.9Poxvirus in a canary (courtesy of LouiseBauck).


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Color 26.10A budgerigar with conjunctivitis, epiphoraand chemosis of seven to ten days’ duration.The etiology is unknown but the clinicalpresentation is similar to that describedwith conjunctivitis in cockatiels. In thiscase, topical application of enrofloxacin re-solved the chemosis within four days (cour-tesy of R. Korbel).

Color 26.11Subconjunctival granuloma in an Amazonparrot. Chemotic conjunctivitis in this birdwas not ameliorated with topical or sys-temic tetracycline and enrofloxacin treat-ment. Ziehl-Neelsen staining of the granu-lomatous conjunctival tissue revealedMycobacterium spp. The conjunctiva wassurgically removed (courtesy of R. Korbel).

Color 26.12An adult Arcuna was presented with a two-week history of progressive depression andweight loss. The bird had a bilateral, serousocular discharge and preferred to keep theeyes shut. Thelazia spp. were noted onphysical examination. The bulk of thenematodes was removed with copiousflushing (LRS), and the bird was success-fully treated with topical ivermectin.

Color 26.13Conjunctivitis in an ostrich caused byflukes (Philophthalmus sp.). This bird washoused in an area that contained a water-fowl pond. Most infected birds are housedin low-lying, damp areas.

Color 26.14Hypovitaminosis A in psittacine birds cancause dysplastic lacrimal gland lesions(courtesy of David Williams).

Color 26.15Cockatiel conjunctivitis frequently re-sponds to therapy with tetracyclines (cour-tesy of Louise Bauck).

Color 26.16Infraorbital sinusitis in a 2.5-year-old In-dian Hill Mynah. Surgical removal ofcaseous masses followed by treatment withenrofloxacin and vitamin A successfully re-solved the lesion (courtesy of R. Korbel).

Color 26.17A four-year-old female budgerigar was pre-sented with a three-week history of pro-gressive ocular swelling and ataxia. Thebird died shortly after presentation. Ab-scesses present in the infraorbital sinusesalso involved portions of the calvarium.

Color 26.18An eight-year-old African Grey Parrot waspresented with a twelve-day history of pro-gressive upper respiratory disease. Thiswas the only companion bird in the house-hold, but the bird had been boarded at a petretailer two months before the onset ofclinical signs. The client also had a flu-likedisease. Chlamydia was detected by usinga fecal antigen test, and the bird respondedto doxycycline therapy. Note the rhinolithin the left naris.


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Pasteurella spp. septicemia and gram-positive coccihave been associated with conjunctivitis in lovebirds.A poxvirus has been described in Masked and Peach-faced Lovebirds.43

Periorbital and Orbital AbscessesPeriorbital disease with exophthalmos or strabismusis most likely to be caused by an abscess of the orbitor lacrimal gland. In some cases, periorbital neo-plasia, either primary or secondary, can cause similarclinical changes. Periorbital abscesses generally re-sult from chronic upper respiratory tract infectionand sinusitis. They are most often seen in cockatiels,and can occur in any position in the orbit (Color26.11). Early treatment of sinusitis reduces the inci-dence of these lesions. Surgical debridement of theabscesses with concomitant systemic antibiotics isthe only effective treatment. Lacrimal sac abscessesmust be differentiated from periorbital abscesses.The lacrimal sac masses present as mobile swellingsat, or immediately anteroventral to, the medial can-thus. Early dacryocystitis can sometimes be treatedby expressing the inflammatory debris through thelacrimal punctum. More severe cases with firm, ne-crotic debris require cannulation and regular flush-ing with antibiotic solutions as dictated by bacterio-logic culture and sensitivity. Surgical removal is notrecommended because of the potential for scarringand long-term nasolacrimal drainage problems.

Periorbital Swelling of Neoplastic OriginAny primary tumor arising in the periorbital orretrobulbar area can cause swelling with or withoutglobe displacement.7 The periorbital area in birdsappears to be a particularly common area for cutane-ous manifestations of lymphoreticular neoplasia,13

represented clinically by periorbital swelling, globedisplacement and feather loss.61,65 Exophthalmia orposteriorly directed strabismus may be noted.

Exophthalmos and globe deviation have been re-ported secondary to optic nerve glioma, orbital roundcell sarcoma,2,26 and some advanced cases of pituitarychromophobe tumors in budgerigars.69 Other lesscommon causes of retrobulbar masses include Myco-bacterium spp.,79 Aspergillus spp. granulomas anddisseminated cryptococcosis.25

Hyperplastic Periocular LesionsProliferative and hyperplastic periorbital lesions aremost commonly seen in budgerigars and canaries inresponse to Knemidokoptes spp. infections. Pitted orhoneycombed, scaly and crusting lesions are easilynoted in the periorbital area as well as on the beak,

vent and legs (Color 26.5). The periorbital lesionsseldom cause problems even though they may bequite severe. Ivermectin can be used topically.

A potential differential diagnosis would include vita-min A deficiency, which can lead to periorbital epi-thelial hyperplasia and hyperkeratosis, but hypovi-taminosis A lesions rarely achieve the size orproliferative extent seen with knemidokoptes. Peri-orbital papilloma-like virus infection in an AfricanGrey Parrot resulted in hyperplastic parakeratoticepithelial proliferations.33 Other periorbital papil-lomas have been described without viral isolation.

Other Periocular DermatosesAny dermatosis (eg, allergic, bacterial, fungal) canpotentially affect the periorbital skin and occur in theperiorbital region (Color 26.4). It should be notedthat many periorbital dermal lesions appear to beexceptionally pruritic and that self-trauma can com-plicate the initial lesions.

Congenital Deformities Although rare in birds, congenital eyelid abnormali-ties do occur and are a surgical challenge to correct.Partial agenesis of the upper eyelid, which was sur-gically corrected by creating a new lateral canthus atthe point at which normal upper eyelid would befound, has been reported in a raptor.37

Cryptophthalmos (fusion of the eyelid margins) hasbeen reported in four cockatiels11 in which dramati-cally reduced or absent palpebral fissures were de-scribed without other ocular abnormalities (Color26.20). Reconstructive surgery was uniformly unsuc-cessful. Behaviorally, the birds appeared normal be-cause some vision was possible through one or botheyes. Corneal dermoids have been reported in onegoose, in which feathers grew out of the aberrantdermal tissue on the lateral aspect of the globe.12

Microphthalmia and maldevelopment of ciliary body,retina and pecten, as well as retinal dysplasias andcongenital cataracts have been described in rap-tors.10 The lacrimal ducts did not drain properly in anUmbrella Cockatoo with choanal atresia, resulting ina chronic ocular discharge (Figure 26.9). Ectropionwith secondary exposure keratitis has been seen incockatiels. This lesion can be resolved with a lateralcanthoplasty (see Chapter 41).


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Conjunctiva

Differential Diagnosis of Conjunctivitis Conjunctivitis can be classified clinically into threegroups. The first are those caused by strictly localfactors, such as localized conjunctival infection orforeign bodies. The second are those in which con-junctivitis is a manifestation of periorbital or orbitaldisease. These are mainly related to sinusitis (seeChapter 22). The third group are those in whichconjunctival hyperemia is caused by a septicemia.Almost any organism causing systemic infection canresult in conjunctivitis. A careful examination of thebird for upper respiratory disease is mandatory indetermining the cause of ocular discharge or conjunc-tival hyperemia (Color 26.10). Exposure to cigarettesmoke, chemical fumes and other aerosolized envi-ronmental toxins should always be considered in thedifferential diagnosis of conjunctivitis, with or with-out signs of upper respiratory disease.

Various infectious agents have been implicated inconjunctivitis, but mere isolation of a bacteria orprotozoan does not imply that it is the cause of thedisease. The conjunctival flora of captive exotic birdshas been surveyed (Table 26.1).80 Bacteria was iso-lated from the upper conjunctival fornix of 71% of thepsittacine birds tested. Staphylococcus sppp. or Co-rynebacterium spp. were isolated from 86% of thebirds. Gram-negative bacteria were recovered from

14% and fungi, from 9% of these clinically normalbirds. In another study, 41% of ocular samples weresterile and 50% of the isolates were gram-positivecocci.82

TABLE 26.1 Avian Conjunctival Flora

Gram + Gram- FungalFamily Isolates Isolates IsolatesAnseriformes 36/68 (56%) 30/68 (44%) 2/27 (11%)Coraciiformes 3/3 (100%) 0/3 (0%) 0/2 (0%)Falconiformes 17/18 (94%) 1/18 (6%) 4/11 (36%)Piciformes 6/7 (86%) 1/7 (14%) 1/5 (20%)Psittaciformes 44/51 (86%) 7/51 (14%) 5/55 (9%)Rheiformes 6/18 (33%) 12/18 (67%) 2/5 (40%)Falconiformes 17/18 (94%) 1/18 (6%) 4/11 (36%)

Adapted from Wolf DE, et al: J Am Vet Med Assoc 183:1232-1233, 1983.

The incidence of gram-positive, gram-negative andfungal organisms was determined in a group of 117birds by swabbing the conjunctiva. The birds sam-pled were clinically asymptomatic and were housedin zoos or pet shops. Staphylococcus spp. or Coryne-bacterium spp. were recovered from 85 of 97 birds inwhich bacterial organisms were recovered. Chlamy-dia spp. was not identified by cytologic evaluation ofconjunctival scrapings in any of the birds.

In one study of domestic ducks, E. coli was isolatedfrom the eyes of a majority of clinically asymptomaticducklings, suggesting that neonatal conjunctivalflora are derived from intestinal flora (Color 26.24).16

The isolation of gram-negative bacteria from the eyeor conjunctiva should be considered abnormal exceptin Anseriformes and Rheiformes, where gram-nega-tive bacteria are considered autochthonous flora.Haemophilus-like bacteria have been reported tocause conjunctivitis in cockatiels.19

Chlamydia psittaci is a frequent cause of keratocon-junctivitis in Australian parakeets23 and of conjunc-tivitis without other signs in pigeons and finches. Inthese cases, treatment with topical oxytetracycline iseffective. Clinical chlamydiosis in Psittaciformes isgenerally associated with conjunctivitis, diarrheaand polyuria.

Mycoplasma spp. are important causes of conjuncti-vitis in pigeons and are suspected in many cases ofconjunctivitis in cockatiels. Ocular discharge andconjunctivitis may be the only presenting signs.Other affected birds may develop rales, nasal dis-charge and sneezing. Unilateral conjunctivitis (one-eyed cold) in pigeons is frequently associated withmycoplasma but can also be caused by chlamydia orsalmonella.

FIG 26.9 A mature Umbrella Cockatoo was presented with a life-long history of ocular nasal discharge. Physical examination indi-cated the lack of a choanal slit and an abnormally formed in-fundibular cleft, preventing normal lacrimal drainage. Theperiorbital tissue was moistened with a serous ocular and nasaldischarge. Note the bubbles in the ocular fluids suggesting that airwas exiting the lacrimal duct.


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Cryptosporidial conjunctivitis has been described inpheasants66 and ducks.48 A case of blepharitis andconjunctivitis in a goose yielded Actinobacillus suis,45

while Mycobacterium avium was isolated from a con-junctival granuloma in an ostrich.31

The presence of foreign bodies in the fornix, or behindthe third eyelid, may be a cause of conjunctival irri-tation and should be suspected in cases of unilateralconjunctivitis that are not responsive to antibiotics.In one study, 7% of the free-ranging Red-shoulderedHawks had grass florets lodged behind the thirdeyelid.49 In companion birds, millet seeds, seed husksand feathers have been associated with a foreignbody conjunctivitis.

Cockatiel ConjunctivitisCockatiels are frequently presented with a conjunc-tivitis from which no infectious agent can be isolated.Clinical signs involve blepharitis and serous oculardischarge, progressing to conjunctival chemosis andinflammation with hyperemic conjunctiva protrud-ing in front of the eye. These signs are seen muchmore frequently in white or albino mutations than inbirds of normal gray color (Color 26.15).

The lesions are often associated with upper respira-tory tract infection, and Mycoplasma spp. andChlamydia spp. have been suggested as agents. Iso-lating mycoplasma requires specialized techniques,and diagnostic samples should be sent in specificmedia to qualified laboratories. Many cockatiels withconjunctivitis are not systemically positive forChlamydia spp., shedding some doubt on the impor-tance of this organism in the cockatiel syndrome.3

Treatment with topical antibiotics often amelioratesthe signs but recurrences are common. Systemic tet-racycline is often curative but should be combinedwith symptomatic treatment of the inflamed perior-bita. Antibiotic ophthalmic ointments may be used orthe eyes can be sprayed with tylosin (l:10 dilution insterile water) or lincomycin and spectinomycin. Theproblem seems to follow familial lines, suggestingthat affected birds should not be used in breedingprograms. In some cockatiels, the conjunctivitis isassociated with partial lid paresis and reduced jawtone (Color 26.6). Many of these birds have giardiasisand respond to treatment with metronidazole andvitamin E. A similar condition has been noted inbudgerigars, and again, the etiologic agent has yet tobe identified.41

Parasitic ConjunctivitisA number of nematode and trematode parasites canoccasionally cause conjunctival irritation in a widevariety of avian species (see Chapter 36). Oxyspiruramansoni is a nematode that has been associated withconjunctival irritation and pruritus in cockatoos, my-nahs and other avian species. This nematode canenter the lacrimal duct and may cause transientepiphora if present in large numbers. Small numbersof nematodes can be manually removed or flushedout of the lower conjunctival sac. Heavy parasiteburdens must be treated with a single topical dose ofivermectin.74 This nematode has an indirect life cy-cle. Nematode eggs are passed through the nasolac-rimal duct, swallowed and passed in the feces, wherethey are consumed by cockroaches (Pycnoscellusspp.). When a bird eats the cockroach, the maturenematode larvae escape into the crop, move up theesophagus and enter the nasolacrimal duct to reachthe eye. Companion birds maintained in indoor envi-ronments are less likely to be infected. Thelazia spp.are reported to cause conjunctivitis in birds but aremore common in mammals (Color 26.12).8

Trematode flukes of the genus Philophthalmus havebeen reported as a cause of conjunctivitis in manyavian species (Color 26.13). The degree of irritationwas sufficient in one group of ostriches to cause thebirds to show persistent lacrimation, irritation andloss of condition. Repeated applications of topicalcarbamate powder eliminated the flukes.29

Cornea

Treating Corneal Ulcers and KeratitisMost corneal problems seen in Psittaciformes areepithelial erosions secondary to trauma or keratitissecondary to lid abnormalities. Fluorescein dye willstain denuded stroma indicating the presence of anulcer. In subtle lesions such as Amazon punctatekeratitis, an ultraviolet Wood’s lamp can be used toaugment the detection of fluorescein retention.Keratitis can be difficult to resolve, but, as a rule,topical antibiotics and corneal bandaging techniquesprovide a sterile environment and time for cornealepithelium to heal (Color 26.22). By extrapolationfrom other species, anticollagenases should be usedin deep ulcers, especially in hotter climates, wherecorneal melting may be a cause of rupture of theglobe. Acetylcysteine can be applied by spray everyfew hours without having to restrain the bird. Atemporary tarsorrhaphy created by placing one ortwo horizontal mattress sutures of 4-0 or 6-0 nylon


686

provides a corneal “bandage.” This is preferable to athird eyelid flap because the muscular action movingthe third eyelid can cause the suture to pull through.The use of a hydrated collagen shield to provide amedicated corneal bandage has not been reported inbirds but may be useful in selected cases. Chroniccorneal erosions may occur in older birds. To providea suitable surface for reattachment of the epithe-lium, devitalized epithelium can be removed with adry cotton-tipped applicator or by using a punctate orgrid keratotomy.

Mynah Bird KeratitisCorneal erosions may be noted secondary to captureand transport in many imported companion birds.The majority of these heal by corneal epithelial mi-gration within 48 hours. Mynahs appear to be espe-cially prone to handling-related keratitis. In onestudy, 96% of birds examined immediately after ship-ping were found to have corneal scratches.36 Ble-pharospasm or some degree of conjunctival hypere-mia is a characteristic finding. Many of these lesionsregress spontaneously in a few weeks, but some maylead to corneal scarring and permanent opacity.Some birds develop a chronic keratoconjunctivitiswith conjunctival masses, severe geographic cornealulceration and corneal vascularization. Systemic as-pergillosis is found in many chronically affectedbirds, suggesting an immunosuppressed condition.Acyclovir-responsive herpesvirus lesions have beensuggested as complicating factors in some affectedbirds.

Amazon Punctate KeratitisA transient keratitis with a characteristic subtlepunctate appearance has been reported in CentralAmerican Amazon parrots. Lesions are bilateral, andthe presenting signs are normally blepharospasmand a clear ocular discharge. The keratitis normallystarts in the medial cornea. In 50% of the birds,lesions progress to cover the cornea but resolve gen-erally within one to two weeks. The lesions are tran-siently fluorescein-positive. A small minority of birdsdevelop more serious lesions with deep corneal ul-ceration and anterior uveitis, manifesting either as aflare and “muddiness” of the iris or as a more severeinflammation with fibrin clots and synechiae (Color26.27). Some birds develop concomitant sinusitis.The use of topical antibiotics or antivirals has notbeen found to significantly alter the outcome of thedisease.36

Amazon parrots from northern South America havealso been reported with a chronic keratitis. There are

fewer cases reported in this group of birds, but theincidence of long-term corneal scarring is higher.

Treatment of more severely affected birds, such asthose with intraocular lesions, includes topical andsystemic antibiotics. Topical corticosteroid to controlintraocular inflammation can reduce the healing ofconcurrent corneal ulceration; topical non-steroidalanti-inflammatories such as indomethacin or flu-bruprofen may be more appropriate in these cases.

Uvea

Uveitis in raptors is most commonly seen as a sequelto intraocular trauma57 and is characterized by aque-ous flare, hypopyon and fibrin clots in the anteriorchamber, iridal hemorrhages or gross hyphema. Thelatter was reported to be the most common ophthal-mologic finding in injured raptors in one survey.58

Uveitis can occur following rupture of the crystallinelens1,54 or secondary to severe extraocular disease inconditions such as poxvirus infection. One case ofbilateral intraocular inflammation with concomitantstaphylococcus septicemia in a lovebird has beenreported.6 Uveitis has been reported in psittacinebirds with reovirus infection in which histopathologicchanges suggested disseminated intravascular co-agulopathy. Hypopyon and hemorrhage, sometimeswith fixed dilated pupils (atypical for uveitis wheremiosis is more common), are characteristic ocularsigns. Birds that recover may have synechiae (Color26.28).17

Clinical signs of uveitis vary, reflecting the diversityof inflammatory states in the eye. Active inflamma-tion may be mild, with increased levels of aqueousproteins causing a flare that reduces the clarity of irisdetail and pupil margin. More severe cases may becharacterized by accumulation of pus or hemorrhagein the anterior chamber. Subtle signs including adarkened iris or more obvious lesions including pos-terior synechiae or organized fibrin clots in the ante-rior chamber suggest a past episode of anterior seg-ment inflammation. Glaucoma is seen secondary totraumatic uveitis in raptors,58 and has been diagnosedwithout concurrent ocular disease in a canary. If the eyeappears painful, enucleation or evisceration is the onlytreatment (Figure 26.10) (see Chapter 41).

Lens

Cataract and lens luxation can occur in birds. Bothconditions can be treated surgically in suitable cases.Cataracts are seen relatively frequently39 and have a


687

wide variety of causes, although in the majority ofcases the etiology is unknown. Senile cataracts havebeen described in macaws (Color 26.30).18

There is clear evidence for familial cataracts in York-shire and Norwich Canaries (Color 26.31).72 A fullypenetrant autosomal recessive gene is responsible forthe condition. In affected canaries, the cataracts weremature with lens-induced uveitis and posteriorsynechiae formation (Color 26.32). In one affected bird,lens resorption had taken place. Lens removal by theirrigation-aspiration technique was unsuccessful inthese birds. Patients requiring cataract removal shouldbe referred to a veterinary ophthalmologist.

Because of the small size of the avian eye, conven-tional extracapsular cataract extraction techniquesare generally difficult. In small birds, soft lenses canbe removed through a 26 ga needle. Phacoemulsifica-tion is the technique of choice for avian cataractremoval in patients with eyes large enough to accom-modate the phacoemulsification probe.38 The extra-capsular technique can be used in intumescent orresorbing cataracts where the lens material can beaspirated or flushed from the anterior chamber(Color 26.34).55 An intracapsular technique has beenused for removal of an anteriorly luxated lens in anowl.9 In eight aging macaws with senile cataracts,the lens was disrupted and removed with an irriga-tion aspiration technique, resulting in vision in 77%of the eyes.18 Post-operative treatment with 17%maxitrol was considered an indispensable part of thetherapy. Topical medications, particularly steroids,must be applied cautiously to small birds to preventintoxication.

Trauma in wild raptors is likely to be a frequentcause for lenticular opacification, and because otherintraocular damage may be present, care should betaken in assessing the bird for cataract surgery(Color 26.34). Assessment should include full evalu-ation of the bird physically, neurologically and, ofcourse, ophthalmoscopically. Ideally, ultrasonicevaluation of the posterior segment should be madeto avoid operating on an eye with a concurrent retinaldetachment. An electroretinogram gives useful dataon retinal function and is suggested prior to surgeryin some cases.30

Miscellaneous Eye Conditions

Retinal DiseasesThe difficulties in examining the posterior segmentof the avian eye, especially in small companion birds,have delayed investigations into retinal disease inthese species. The pioneering work of Casey Wood inthe early part of this century on the normal avianfundus has not been surpassed even with the ad-vances in ophthalmoscopic instrumentation and thegrowing interest in avian ophthalmology.81

Nevertheless, some reports of retinal disease in birdshave found their way into the literature. Wood him-self noted a high prevalence of posterior segmentinflammatory lesions in captive raptors, and otherauthors have confirmed his findings.28,56,58 Lesionsinclude pigmentary deposits on the otherwise unpig-mented peripheral retina, focal scarring, pre-retinalmembranes, vitreal opacities and gross inflamma-tory disease of the entire posterior segment (Color26.35). Many of these lesions in free-ranging birdsmay be caused by trauma with hemorrhage thatcauses vitreal scarring and contraction. Posteriorsegment bleeding may result from choroidal vessels,a damaged ciliary body, or even in some cases, rup-ture of the pecten.

Toxoplasmosis has been suggested as a cause of reti-nal lesions in raptors (see Chapter 36). This report,however, was based on identifying seropositive birdsin a population where the seroprevalence is un-known.28 Toxoplasmosis was confirmed as a cause ofretinitis and blindness in canaries. Toxoplasmosiswas diagnosed in a group of canaries with crustyocular lesions, white lesions in the vitreous humorand, in most cases, collapse of the globe. Several ofthe infected birds had neurologic signs characterizedby circling and head tremors. High latex agglutina-tion antibody titers to T. gondii were seen in five ofthe seven affected birds. Histologically, T. gondii

FIG 26.10 Although evisceration or enucleation can be disfiguring,these procedures may be life-saving in cases of severe infections orneoplasms.


688

tachyzoites were demonstrated in the detached andintact retina, the lens and in exudate in the vitreoushumor.76

Retinal detachment can occur through trauma, butidiopathic bilateral detachments have been noted inpheasants unassociated with mechanical damage.67

Retinal dysplasia has been diagnosed in raptors,21,60

and a retinal degeneration of unknown origin wasreported in a parakeet.75

Intraocular TumorsIntraocular tumors are rare in birds. Malignant in-traocular medulloepithelioma has been reported intwo-year-old cockatiels in which, after enucleationfor presumed bacterial panophthalmitis and orbitalcellulitis, tumor masses grew rapidly in the orbit.70

An intraocular adenocarcinoma has been reported ina budgerigar.22

Neurophthalmology and Central BlindnessBlindness in birds may be caused by opacity of thevisual media, retinal lesions or central neurologicdisease. In cases where no obvious ocular cause ofblindness can be observed, an electroretinogram canbe used to differentiate between retinal or centrallesions.47

Causes of central blindness may include cataracts,neoplasia or encephalitis that may be localized orrelated to systemic disease. Heavy metal toxicitiescan result in blindness, but the visual changes areonly one of a number of multifocal nervous signs.Space-occupying brain lesions, particularly pituitary

adenomas, can cause visual deficits from pressurebeing placed on the optic chiasm. One large survey of50 chromophobe pituitary tumors reported centralblindness in a number of birds with associatedneurologic and endocrine signs.4,69

Defects of cranial nerves III, IV and VI are somewhatdifficult to appreciate in birds because there is rela-tively little torsional movement of the globe withinthe orbit. Horner’s syndrome was suggested as adiagnosis in one bird in which a unilateral ptosis andmild miosis ameliorated by topical phenylephrinewas noted.78

Evaluating the Blind Bird: Determining if visuallydefective birds are sound for release can be difficult.Some birds such as owls perform well with one eye,while releasing a one-eyed diurnal falcon to the wildmight be considered unwise. Many companion birdscan survive remarkably well with little or no vision,as has been noted with cockatiels with cryptophthal-mos11 and Bobwhite Quail with dense bilateral cata-racts;44 however, blindness can be very debilitating insome smaller Passeriformes where flying from perchto perch is behaviorally important.

EnucleationEnucleation is frequently necessary in birds becauseof trauma, non-responsive inflammation or tumors.Enucleation is difficult because of the large size of theavian eye and the tight fit of the globe into the orbit.For further information on enucleation and otherophthalmic surgeries, see Chapter 41.

References and Suggested Reading

1.Anderson GA, Buyukmihci N: Pha-coanaphylactic endophthalmitis in anowl. Vet Pathol 20:776-778, 1983.

2.Arnall L: Anaesthesia and surgery incage and aviary birds. Vet Rec73:188, 1961.

3.Bauck L: Three treatment protocolsfor cockatiel conjunctivitis. Proc As-soc Avian Vet, 1989, pp 92-96.

4.Bauck L: Pituitary neoplastic diseasein budgerigars. Proc 1st Intl ConfZool & Avian Med, Hawaii, 1987, pp87-90.

5.Bellhorn RW: Laboratory animal oph-thalmology. In Gelatt KN (ed): Veteri-nary Ophthalmology. Philadelphia,Lea & Febiger, 1981.

6.Bounous DI, Schaeffer DO, Roy A: Co-agulase-negative Staphylococcus sp.septicaemia in a lovebird. J Am VetMed Assoc 195:1120-1121, 1989.

7.Brightman AH, Burke TJ: Eyelid tumorin a parakeet. Mod Vet Pract 59:683,1978.

8.Brooks DE, Greiner EC, Walsh MT: Con-junctivitis caused by Thelazia sp. in aSenegal parrot J Am Vet Med Assoc183:1305-1306, 1983.

9.Brooks DE, Murphy CJ, Quesenbury KE,Walsh MT: Surgical correction of aluxated cataractous lens in a barredowl. J Am Vet Med Assoc 183:1298-1299, 1983.

10.Buyukmihci NC, Murphy CJ, Schulz T:Developmental ocular disease of rap-tors. J Wildl Dis 24:207-213, 1988.

11.Buyukmihci NC, et al: Eyelid malfor-mation in four cockatiels. J Am VetMed Assoc 196:1490-1492, 1990.

12.Busch TJ: Corneal dermoids in agoose. New Zeal Vet J 33:189-190,1985.

13.Campbell TW: Neoplasia. In HarrisonGJ, Harrison LR (eds): Clinical AvianMedicine and Surgery. Philadelphia,WB Saunders Co, 1986, p 507.

14.Campbell TW: Conjunctival cytology.In Campbell TW: Avian Hematologyand Cytology. Ames, Iowa State Uni-versity Press, 1988.

15.Cavill JP: Canary pox: Report of anoutbreak in roller canaries (Serinuscanarius). Vet Rec 76:463-465, 1964.

16.Chalmers WSK, Kewley DR: Bacterialflora of clinically normal conjunctivaein the domestic duckling. AvianPathol 14:69-74, 1985.

17.Clubb SL: A multifactorial diseasesyndrome in African grey parrots(Psittacus erithacus) imported fromGhana. Proc Intl Conf Avian Med,1984, pp 135-149.

18.Clubb SL, Karpinski L: Aging in ma-caws. Proc Assoc Avian Vet, 1992, p85.

19.Devriese LA, Vianene N, Uyttebroek E,et al: Three cases of infection byHaemophilus-like bacteria in psittac-ines. Avian Pathol 17: 741-744, 1988.

20.Dorrestein GM, van der Hage MH:Aviculture and veterinary problemsin lovebirds. Proc 1st Intl Conf Zool &Avian Med, Hawaii, 1987, pp 243-261.

21.Dukes TW, Fox GA: Blindness associ-ated with retinal dysplasia in a prai-rie falcon (Falco mexicanus). J WildlDis 19:66-69, 1983.

22.Dukes TW, Petit JR: Avian ocular neo-plasia - a description of spontane-ously occurring cases. Can J CompMed 47:33-36, 1983.

23.Emanuelson S, Carney J, Saito J:Avian pox in two black-maskedconures. J Am Vet Med Assoc173:1249-1250, 1978.

24.Evans HE: Organa senoria. InBaumel JJ, et al (eds): Nomina

Anatomica Avium. London and NewYork, Academic Press, 1979.

25.Fenwick B, Takeshita K, Wong A: AMoluccan cockatoo with dissemi-nated cryptococcosis. J Am Vet MedAssoc 187:1218-1219, 1985.

26.Frost C: Experiences with pet budg-erigars Vet Rec 73:623, 1961.

27.Graham CL: Poxvirus infection in aspectacled Amazon parrot (Amazonaalbifrons). Avian Dis 22:340-343,1978.

28.Greenwood AG, Barnett KC: The in-vestigations of visual defects in rap-tors. In Cooper JE, Greenwood AG(eds): Advances in the Study of Rap-tor Diseases. Keighley, England, Chi-ron Publications, 1981.

29.Greve JH, Harrison GJ: Conjunctivitiscaused by eye flukes in captive-reared ostriches. J Am Vet Med As-soc 177:909-910, 1980.

30.Hacker DV, Shifrin M: Cataract ex-traction in a Mandarin duck. J AmAnim Hosp Assoc 24:679-682, 1988.

31.Hood HB: Eye pathology in an adultmale ostrich (Struthio camelus). ProcAm Assoc Zoo Vet, 1978.

continued on page 694


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Ophthalmology

Color 26.19a,b) A mature Sun Conure was presentedwith an idiopathic occurrence of unilateralperiocular hemorrhage. There was noknown trauma and clinicopathologic find-ings were limited to mild anemia (PCV=35).The bird fully recovered and had no furtherproblems.

Color 26.20Cryptophthalmos with ankyloblepharon ina two-year-old male cockatiel. Surgery torestore a normal palpebral aperture wasunsuccessful (courtesy of N. Buyukmihci).

Color 26.21Snowy Owl with ulcer and corneal calcifi-cation caused by trauma. A punctate or gridkeratotomy to restore normal epitheliza-tion would be indicated (courtesy of K.C.Barnett).

Color 26.22Fungal keratopathy in an ostrich secon-dary to sand contamination of the eye. Athird eyelid flap was attempted but thesutures failed because of the muscular ac-tion of the nictitating membrane. The birdresponded to treatment with topical keto-conazole (courtesy of S. West).

Color 26.23Corneal ulceration and globe collapse fromunknown etiology in a seagull. The eye wasenucleated.

Color 26.24Conjunctivitis in a farm duck. Cultureyielded Acinetobacter sp. and the lesionsresolved using topical chloramphenicolointment.

Color 26.25Luxation of the lens and uveitis in an owlthat was hit by a car. Luxation of the lensmay cause an increase in intraocular pres-sure that must be resolved with an intra-capsular lentectomy. Topical steroids wereeffective in controlling the uveitis in thiscase (courtesy of S. West).

Color 26.26Keratic precipitates on the posterior corneaof a Screech Owl with phacolytic uveitis andbilateral cataracts (courtesy of S. West).

Color 26.27Uveitis and cataract in an Amazon parrot.Note the darkening and “muddy” appear-ance of the iris. These changes are charac-teristic of uveitis not complicated by hy-popyon (courtesy of Dan Wolf).


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Ophthalmology

Color 26.28Tawny Owl with uveitis. Examinationwith a slit lamp showed that the whiteglistening of the eye was caused by hy-popyon and not a corneal lesion. Resolu-tion with topical steroid medication wasslow and several synechiae remained. Noetiologic agent could be identified (cour-tesy of David Williams).

Color 26.29An adult male cockatiel was presented witha three-week history of ocular dischargeand scratching of the face. A severe pan-ophthalmitis was noted on physical exami-nation. The bird’s WBC count was 22,000.A conjunctival scraping revealed numerousgram-negative bacteria, both free andwithin conjunctival cells. The bird wasplaced on systemic and ophthalmic antibi-otics. Cultures indicated Pseudomonas spp.The eye did not respond to therapy, andenucleation was performed six days afterinitial presentation.

Color 26.30Cataract in an Eclectus Parrot. The perior-bital feather loss is probably secondary tothe bird’s rubbing the area because of re-duced vision in the eye (courtesy of DavidWilliams).

Color 26.31Inherited cataract in a Norwich Canary.Note also the polycoria probably sub-

sequent to senile iridal atrophy (courtesy ofDavid Williams).

Color 26.32Cataract and posterior synechiae in a thir-teen-year-old canary. Phitisis bulbi withwrinkling of the lid margins are also evi-dent (courtesy of R. Korbel).

Color 26.33Cataract in a mynah bird with posteriorsynechiae. In this case, the contralateraleye was unaffected, the bird’s behaviorwas normal and surgical removal of thecataract was not attempted (courtesy ofK.C. Barnett).

Color 26.34Cataract in a Harris Hawk. Note the scin-tillating appearance of the cataract, indi-cating some resorption. The iris ectropionis believed to be a congenital anomaly andnot reflective of a uveitis. Extracapsularcataract extraction was performed and thebird regained vision in the eye (courtesy ofDavid Williams).

Color 26.35 a) Normal pecten in an Eagle Owl (courtesyof David Williams). b) Gross retinal post-inflammatory scarring in a Tawny Owl. Ithas been suggested, but not confirmed, thatthis scarring may be a result of toxoplas-mosis (courtesy of K.C. Barnett).


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32.Jacobson ER, Gardiner C, Clubb S: Ade-novirus-like infection in white-masked lovebirds (Agapornis per-sonata). J Assoc Avian Vet 1:32-34,1989.

33.Jacobson ER, et al: Papilloma-like vi-rus infection in an African grey par-rot. J Am Vet Med Assoc 183:1307-1308, 1983.

34.Johnson BJ, Castro AE: Canary poxcausing high mortality in an aviary. JAm Vet Med Assoc 189:1345, 1986.

35.Karpinski LG, Clubb SL: Post pox ocu-lar problems in blue-fronted and blue-headed pionus parrots. Proc AssocAvian Vet, 1985, p 91.

36.Karpinski LG, Clubb SL: Clinical as-pects of ophthalmology in cagedbirds. In Kirk RW (ed): Current Vet-erinary Therapy IX. Philadelphia,WB Saunders Co, 1986, pp 616-621.

37.Kern, TJ, Murphy CJ, Heck WR: Partialupper eyelid agenesis in a peregrinefalcon. J Am Vet Med Assoc187:1207, 1985.

38.Kern TJ, Murphy CJ, Riis RC: Lens ex-traction by phacoemulsification intwo raptors. J Am Vet Med Assoc185:1403-1406, 1984.

39.Keymer IF: Cataracts in birds. AvianPathol 6:335-341, 1977.

40.Korbel R: Tonometrie am Vogelauge.III. DVG- Tagung Vogelkrht,München, 1992.

41.Korbel R, Schäffer EH: Zum Vorkom-men einer konjuntivitis unbekannterÄetiologie bei Wellensittichen (Melop-sittacus undulatus Shaw, 1805). [Con-junctivitis of unkown pathogenesis inbudgeridgars.] Tierärztl Prax 19: 659-663, 1991.

42.Koschmann JR: Vitamin A deficiencyin caged birds. Texas Vet Med J48:25, 1986.

43.Kraft V, Teufel P: Nachweis einesPockenvirus bei Zwergpapageien(Agapornis personata und Agapornisroseicollis). Berl Munch TierartzlWschr 84:83-87, 1971.

44.Krehbiel JD: Cataracts in bobwhitequail. J Am Vet Med Assoc 161:634-637, 1972.

45.Maddux RL, Cgengappa MM, McLaugh-lin BG: Isolation of Actinobacillussuis from a Canada goose (Branta ca-nadensis). J Wild Dis 23:483, 1987.

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