Retina and retinal vascular diseases

Dr Mahmood FauziASSIST PROF OPHTHALMOLOGY

AL MAAREFA COLLEGE

Objectives

Explain the clinical anatomy of retina and retinal microcirculation

Enumerate retinal diagnostic procedures -Retinal examination

Describe patho-physiology and clinical presentation and management of retinal vascular disorders ie- (a) Periphlebitis (b) Central retinal artery/ vein occlusion (c)Retinopathy-diabetic and hypertensive

• Other retinal conditions(Macular Degeneration, Retinitis Pigmentosa, Retinal Detachment, Retinal Dystrophy,Retinoblastoma)

Clinical anatomy of retina

Retina converts light rays into electrical impulses and sends towards brain through optic nerve.

Contain photoreceptors-rods and cones. Blood supply The central retinal artery(branch of

opthalmic artery) enters the globe from the center of the optic nerve, immediately adjacent and parallel to the exiting central retinal vein.

Inner layer→ central retinal vascular system

Outer layer→ choroid（ciliary vascular system）

Macula lutea→ choriocapillaries Inner barrier（blood–retina

barrier） Dense connection of retinal capillary endothelium

Outer barrier（choroid-retina barrier）

zonula occludens between the RPE RPE- Bruch’s membrane +choriocapillaries complex

Retina is 0.56 mm thick near optic disc, 0.1 mm at ora serrata

Thinnest at center of fovea

Rods contain photo chemical called Rhodopsin mainly responsible for black and white / dark vision.

Cones: contain light sensitive photochemical (color pigment) responsible for color vision

Macula- yellow spot near the center of the retina, Diameter around 5 mm.

Fovea is present at the center of macula , responsible for sharp central vision.

Optic disc: (blind spot) area where retinal nerve fibres join to form optic nerve, no rods and cones present here.

Functions of retinaForm senseColor visionDark adaptation

Diagnostic Procedures Of Retina

Fundus examination by Ophthalmoscopy (A) Direct Ophthalmoscopy (B) In-Direct OphthalmoscopySlit lamp examination with 70-9O D

Digital Fundus Photography

Fluorescein angiography

Ultrasonography b-scan

Optical coherence tomography(OCT)

Retinal examinationIn-Direct OphthalmoscopyDirect Ophthalmoscopy

Opthalmoscope Fundus

Indirect slit-lamp biomicroscopy

Fluorescein Angiography

Optical coherence tomography(OCT)

Ocular ultrasound

Retinal vascular disorders

Periphlebitis retinae Inflammation of the wall of the retinal veins commonly due to

1. tuberculosis (Mycobacterium tuberculosis).2. Sarcoidosis, 3. multiple sclerosis,4. Eales Disease (“periphlebitis retinae).

Cause hemorrhages in retina and vitrus Commonly effect adult(20-30 year) Cause sudden loss of vision due to vitrus hemorrhage Treatment Control the basic eitiology Corticosteroid help to control inflammation Photocoagulation (laser) of leakage area

Central retinal artery occlusion-CRAO

It is obstruction of the circulation of the retina due to embolus and thrombosis.

Caused by hypertension and arteriosclerosis .

Commonly results in complete or permanent blindness.

FFA in CRAO- complete absence in filling central retinal artery

Symptoms

Signs

Sudden painless vision lose of one eye

Direct light reflex disappear, indirect light reflex normal

Retinal edema、 cherry-red spotRetina artery narrowing， retinal hemorrhages

Treatment Vasodilator (acetylencholine p.s effect) dilate the spasm artery acetylsalicylic acid(aspirin) to prevent clot formation

Central retinal vein occlusion - CRVO Obstruction due to veins circulation thrombosis and embolus Caused by hypertension , Arteriosclerosis Predisposing factor advancing age Causes sudden impairment of vision not sudden loss of vision

Ischemic type CRVO Non-Ischemic type CRVO

TYPES : Nonischemic CRVO is milder form of disease. May

present with good vision, few retinal hemorrhages and cotton-wool spots, no relative afferent pupillary defect, and good perfusion to the retina. May resolve fully with good visual outcome or may progress to the ischemic type.

Ischemic CRVO is severe form of the disease.May present initially as the ischemic type, or it may progress from nonischemic. Usually, presents with severe visual loss, extensive retinal hemorrhages and cotton-wool spots, presence of relative afferent pupillary defect, poor perfusion to retina, and presence of severe electroretinographic changes. In addition, patients may end up with neovascular glaucoma and a painful blind eye.

Non-Ischemic CRVO Ischemic CRVO

NON ISCHEMIC CRVO –Diffuse flame shaped retinal hemorrage Tortuosity and engorgenent of retinal veins

ISCHEMIC CRVO: diffuse capillary non perfusion—rubiosis iridis—neovascular glaucoma(NVG)

Causes Central retinal vein obstruction has been associated with various systemic

pathological conditions, although the exact cause and effect relationship has not been proven.

Some of the conditions in which CRVO has been associated include the following:

Systemic vascular disease - Hypertension, diabetes mellitus, cardiovascular disease

Blood dyscrasias - Polycythemia vera, lymphoma, leukemia Clotting disorders - Activated protein C resistance, lupus anticoagulant,

anticardiolipin antibodies, protein C, protein S, antithrombin III Paraproteinemia and dysproteinemias - Multiple myeloma,

cryoglobulinemia Vasculitis - Syphilis, sarcoidosis Autoimmune disease - Systemic lupus erythematosus Oral contraceptive use in women Obstructive sleep apnea - This affects more patients with retinal vein

obstruction than other disorders; treatment of the sleep apnea may help prevent central vein obstruction.[11]

Other rare associations - Closed-head trauma, optic disc drusen, arteriovenous malformations of retina

Treatment exact pathogenesis of the CRVO is not known Identifying and treating any systemic medical problems

to reduce further complications is important Advocated treatments are as follows: Aspirin Anti-inflammatory agents Isovolemic hemodilution Plasmapheresis Systemic anticoagulation with warfarin, heparin, and

alteplase Fibrinolytic agents Systemic corticosteroids intravitreal injection of anti-angiogenic drugs like ranibizumab , aflibercept , triamcinolone , bevacizumab Dexamethasone intra vitreal implants

Hypertensive retinopathy Fundus changes occurring in

patient suffering from systemic hypertensive due to vaso-construction and arteriosclerosis etc.

High blood pressure can cause damage to blood vessels in the eyes.

Cause headaches and visual disturbance.

Treatment • A major aim of treatment is to prevent target organ damage by

high blood pressure • Control of high blood pressure (hypertension) is the only

treatment for hypertensive retinopathy• Regular eye examinations are important.

Vaso-constrictive and early sclerotic changes in hypertensive retinopathy, including diffuse arteriolar narrowing, sinusoidal tortuosity, copper wire appearance, arteriovenous crossing changes, tapering of veins and increased arteriolar branching angles.

The changes seen in the fundus secondary to hypertension are representative of changes taking place in the arterioles throughout the body.Grading of hypertensive retinopathy : grade I, generalized arteriolar narrowing; grade II, generalized narrowing and focal constrictions; grade III, more narrowing, focal constriction, hemorrhage, and exudation; grade IV, marked narrowing and focal constrictions with hemorrhages, exudates, and papilloedema of the disc.

Diabetic retinopathy

http://www.jirehdesign.com/

Incidence of d. retinopathy related to the duration of diabetes 15% after 5 year50% after 10 year60% after 15 year70% after 20 year 90% after 30 year

Retinopathy effects the circulatory system of the retina

Causing damage of blood vessels of eye

Leakage of blood (hemorrhage)

fluid leakage (oedema)

Commonly cause blindness or loss of vision

Cause darkening in image

1.Background retinopathy

small red dots will appear on retina due to tiny

swellings in the blood vessel walls

3.Proliferative retinopathyIt is third stage of retinopathyextensive neovascularization, usually causing a sudden loss of vision

2.Pre-proliferative retinopathyretina swells and leaks blood reading small print may become particularly difficult.

TREATMENTBackground retinopathy Requires no treatment, but should have Regular

eye Examinations by Ophthalmologist

Pre-proliferative retinopathy also does not require treatment, Laser treatment can be an option if leakage

begins Laser treatment cannot restore any lost vision,

but can be used to prevent further growth

Proliferative retinopathy Laser treatment is used to 'burn' the abnormal

blood vessels to prevent further growth of new blood vessel

Diabetic maculopathy

Involvement of fovea occur at any stage of retinopathy due to

Macular edema Macular hemorrhages Macular detachment

Other retinal disorders

Macular degeneration Also called age related macular

degenerationIt is a non heredity most common cause

permanent irreversible central loss of vision

Age related macular degeneration-AMRD

Type Nonexudative(atrophic or dry) 90% most

common type of MD

Exudative(wet):10% cause of ARMD presence of fluid and hemorrhages it is more dangerous

TreatmentAntivascular endothelial growth factor-

AVEGF(avastin)Photodynamic therapy(PDT)

Retinal detachment Separation of sensory retina from

pigmented epithelium is called retinal detachment

Types Primary or simple: separation of

retina in the form of hole or tear. This hole allows the vitreous to raise retina from its normal position

Secondary: due to pathology and the accumulation of fluid to push retina from its normal position

Treatment-Laser treatment Retinopexy use to reattach the detached retina.

Rhegmatogenous retinal detachment formation

retinal degeneration Basis liquefied vitreous retinal hole→RD aging

Predisposing high myopia ocular trauma

Pigmented retinal dystrophy It is a heredity disease caused degeneration of

rods and cones in childhood caused night blindness as well as complete blindness

Retinoblastoma Rapidly developing carcinoma which develops

in the cells of the retinaIt is common congenital tumor of retina

occurring in childhood(2-4) year. Approximately 1in 20,000 birth

Children of the same family usually effected due to Rb oncogene involved.

Many children have unilateral retinoblastoma which has an excellent prognosis. The prognosis for bilateral involvement depends on the size and location of the tumor. 

Treatment

Laser therapy: A laser is used to vaporize the tumor

Thermotherapy: This process uses heat to destroy the cancer cells may be combined with chemotherapy or radiotherapy

Chemotherapy: Chemotherapy is the use of anti-cancer (cytotoxic) drugs to destroy cancer cells

Night blindness

Due to deficiency of vitamin- AV-A is present in cytoplasm of rods and

pigmented layer of retinaWithout the V-A the amount of retinal and

rhodopsin may severally depressed this condition is known as night blindness

Color blindness As cones are responsible for color

vision The missing of single group of

cones from RGB the person unable to distinguish some color from other this condition is called color blindness

If the red cone is missing this condition is called protonpe

If green cone is missing this condition is called deutarnope

Red-green color blindness is a genetic disorder inherited from mother

And in rare cases blue cone missing

Diagnosis- Ishihara Chart

Resources http://

www.mayoclinic.org/diseases-conditions/retinal-diseases/basics/definition/con-20036725

http://www.sciencedirect.com/science/journal/13509462

http://www.snec.com.sg/eye-conditions-and-treatments/common-eye-conditions-and-procedures/Pages/retinal-vascular-disorders.aspx

http://www.academy.org.uk/lectures/barnard5.htm