DR. PARAMESWARA RAO(PROFESSOR) DR.SIVA KUMAR( PG)

AT BIRTHFovea contains many layersOra serrata is less developedThere is a fold of redundant retina called Lange’s fold.Thicker retinaPeripheral retina circulation develops only in the last trimester of gestation.

WITH AGE1. RPE ---Melanin granules lose oval contour—

become rounded--- basement membrane thickens----focal mould like refractile excrescences known as Drusen

(mucopolysaccharides and dystrophic calcification) develop in that part of bruchs membrane

WITH AGE Contd…2.Vacuoles appear in the inner nuclear and outer plexiform layer in the temporal aspect

of ora serrata----coalesce to form cysts- called BLESSING IWANOFF CYSTS.

3. Degenerative changes prominent in the periphery and macula as any decrease in the blood flow of large arteries the distal arterioles are first affected.

Retinal vasculature at the age of 81/2 months….80 % of retina is perfused…. Peripheral retina especially the temporal side of disc is less perfused…

Premature infants, bilateral After birth if high oxygen is given to these

infants---transient(10min) obliteration of terminal arterioles---dilatation of the vessels---delayed reversible obliteration---delayed irreversible vaso obliteration---vasoproliferative changes---angiogenesis---invade ILM---into vitreous---haemorrages, exudates, gliosis --- preretinal membranes---retrolental mass (DD-leucocoria) ---RD

This reaction is peculiar only to incompletely vascularised retina.

A fully vascularised retina does not react to hyperoxygenation in this way

COLOBOMA Due to abnormal closure of fetal fissure

mostly inferonasalThe RPE is totally absent in the coloboma region or merely represented.

MEDULLATED NERVE FIBRESNormal medullation stops at the lamina cribrosa at birth. Rarely MNF’s appear near the disc or elsewhere. Usually presence of

such a sheath does not interfere with the function

of affected fibres but reduces transparency of

retina producing a scotoma

ALBINISM Gross absence of macula / hypoplasia of macula

OGUCHI’S DISEASE Total absence of Rods. Abnormal no of cones present. Retardation of dark adaptation.

RETINAL DYSPLASIA Dev. Aberration(proliferation and infolding

of outer layers of retina) which is present at birth.

Pre retinal hemorrage Seen in proliferative retinopthy , trauma,

subarachnoid hemorrhage, valsalva retinopathy, shaken baby syndrome etc..

Round or boat shaped

Superficial hemorrages Seen in CRVO ,HTN retinopathy, background

dr, Periphlebitis etcFlame shaped…seen in the nerve fibre

layer

Mechanism: Marked congestion of capillaries --- marked

edema of affected tissues ----capillaries of the NFL rupture--- flame shaped haemorrages in the

NFL

ROTH SPOTSHaemorrhages with white centresSeen in anaemias , leukemias, HIV retinopathy, SABE etc

Deep hemorrhagesAlso called dot and blot haemorrhages.Mainly diabetic retinopathy.

Mechanism :Degeneration of the deep capillary walls ---lead to hemorrhages in the inner nuclear layer----dot and blot hemorrhages

Seen between layer of rods and cones and RPE

Large bright red indistinct outline Seen in choroidal neovascularisation ,COAT’

s dis, Sickle cell anaemia, blunt trauma

Between RPE and bruch’s membrane Choroidal neovascularisation is the common

cause.

Yellowish waxy plaques with relatively distinct margins seen in the inner nuclear layer of retina.

Mechanism: Formed mainly due prolonged leakage from

the capillaries. Seen in rings/clumps : diabetis , old BRVO ,radiation retinopathy, telangiectasias stellate : htn , papilledema, neuroretinitis sub retinal : CNVM, COAT’s, toxocara

canis

Cotton wool spots. Seen in the NFL layer Cottony appearance with frayed edges

central fibrin and peripheral mucopolysaccharide

Mechanism : Decreased perfusion ---micro infarcts in the NFL----blockage in the axoplasmic flow--- cotton wool exudates are formed

Seen in HTN retinopathy , CRVO, HIV, Scleroderma, Pre proliferative DR, systemic vasculitis

PathogenesisArterial occlusion---the vascularity of the

involved retina is decreased---cloudy swelling of the affected retina---affected part becomes opaque---fovea retains its reddish hue as it is supplied by choricapillaries---CHERRY RED SPOT

Because of the low perfusion --- inner retinal layers undergo coagulative necrosis---microglia remove the debris---small or large infarcts formed---formation of cotton wool spots in NFL due to blockage of axoplasmic flow.

CHERRY RED SPOT(DD)The mechanism by which a cherry red spotis formed in niemann-pick and tay-sachs is differentDue to defective metabolism(lipoidal degeneration) sphingolipids get accumulated---ganglion cells are more susceptible---retina becomes opaque in areas where ganglion cells are more---as ganglion cells are absent in macula it retains

it natural colour---appearance of cherry red

spot

Central Retinal Artery Occlusion

Branch Retinal Artery Occlusion

Afferent Pupillary DefectCherry Red SpotRetinal Edema

Pathogenesis: Venous occlusions---marked congestion of

capillaries---marked edema of affected tissues---hemorrhages and soft exudates in the NFL---large hemorrages in the entire thickness of retina---may erupt through ILM---pre retinal hemorrhage---edema may escape sub retinally to produce flat detachment of retina

Final outcome : organization of hemorrhages, formation of blood vessels on the inner retinal surface extending into vitreous.

Central Retinal Vein Occlusion

Branch Retinal Vein Occlusion

Fibrino platelet Cholesterol(hollen horst) Calcific

Normally the vessels are seen as columns of pigmented RBC’s filling the lumina

Retinal arteriolar sclerosis- obscures blood column- light reflex is widened and imparts an orange or coppery hue to the arterioles

Process prolonged- perivascular fibrosis may totally hide the blood column – silver wire appearance

Normally at the AV crossing T.adventitia forms a common sheath for artery and vein AND the vein passes under the artery at a rather acute angle

At AV crossings--- due to thickening and increased rigidity of of the arteriolar wall- venular wall is compressed (tapering gunn’s sign)-vein is dilated distal to the crossing(bonnet’s sign) –deflection of veins at obtuse angle (salu’s sign).

Long standing HTN- Tributary venous occlusions – usually temporal vein is occluded because of more arterial crossings

Necrosis of capillary walls- supericial haemorraghes

Microinfarcts in the NFL – SOFT EXUDATES

Grade I :It consists of mild generalized arteriolar attenuation, particularly of small branches, with broadening of the arteriolar light reflex and vein concealment.

Grade II : It comprises marked generalized narrowing and focal attenuation of arterioles associated with deflection of veins at arteriovenous crossings (Salus’ sign).

Grade III : This consists of Grade II changes plus copper-wiring of arterioles, banking of veins distal to arteriovenous crossings (Bonnet sign), tapering of veins on either side of the crossings (Gunn sign) and right-angle deflection of veins (Salu’s sign). Flame-shaped haemorrhages, cotton-wool spots and hard exudates are also present.

Grade IV :This consists of all changes of Grade III and silver wiring with papilloedema.

HTN RETINOPATHY

SOFT EXUDATES

MALIGNANT HTN: Edematous fluid diffuses through all layers

--- collects in pools in the fibre layers ---fluid contains fibrin, debris,lipids,proteins---visible as hard exudates at the jn of INL and OPL---macular region--- MACULAR STAR

Rarely focal choroidal infarction with patchy proliferation of RPE is evident clinically as elschnig spots and siegrist lines (increased pigmentation along a sclerotic vessel)

Basic pathology : thickening of the basement membrane and ischaema

Loss of pericytes ( normal endothelial to pericyte ratio is 1:1. Pericytes have contractile properties and inhibit endothelial proliferation)

As the capillaries become acellular and their contractile nature is lost --- microaneurysms are formed---leakage may produce hard exudates

Aneurysmal wall break down- dot and blot hemorrhages

IRMA : Increased aggregation and stickiness of platelets leads to--extensive closure of capillary – capillary non perfusion – ischemia of retina. Seen in mid retinal periphery – leads to opening up shunt vessels- run from arterioles to vennules. Often referred to – Intraretinal microvascular abnormalities (IRMA).

Venous engorgement --- release of angiogenic factors--- NVD/NVE/ Rete mirabile ---vitreous haemorrhage---fibrovascular proliferation --- RD

BLOW OVER THE EYE--- immediate changes in the retinal cells and vessels---vasoparalysis ---leakage of fluid into the tissuses--- edematous fluid accumulates more in the OPL--- hence in the macula (berlin’s)--- there will be RPE degeneration – small cystic spaces--- large spaces--- ILM breach macular hole formation ---- RD

ACUTE CHRONIC- granulomatous non granulomatous

Any inflammation--- vascular dilatation---increased fluid leakage from the vessel wall--- pressure by the fluid leads to degeneration of retinal elements---macrophages accumulate to remove the debris of the dead cells--- subsequent compensatory proliferation of the RPE along the periphery of the lesion( pigmented scar)---proliferation of glial tissue---fibro glial scar---distortion and folding of retina

The progress and the severity of the inflammation depends on the element causing it.

Tuberculosis Sarcoidosis Syphilis Toxoplasmosis etc

LOSS OF RODS starts at the equator----subsequent degeneration of other photo receptor cells--- RPE proliferates and invades the atrophic retina along the blood vessels forming cuffs perivascular cuffs of intensely pigmented cells--- appear as bony spicules

Vascular walls are thickened and gliotic Remaining outer retina adheres to the

bruchs membrane

Massive opacification of RPE- due to massive accumulation of yellowish brown pigment in the cytoplasm of RPE cells---tall RPE cells with pigment give this characteristic appearance----form fish tail opacities in the periphery

Later RPE dysfunction and death of sub foveal RPE cells – photo receptor degeneration and atrophic macular degeneration

Lipofucsin deposition in the RPE INITIAL EGG YOLK APPEARANCE Egg SCRAMBLING---chorio retinal scarring

develops Impaired metabolism of the RPE

Separation of photoreceptor layer from RPE Inflammatory– exudative—either

localised /diffuse Tractional – organisation of inflammatory

exudates/ haemorrages /glial tissue Rhegmatogenous- break in the retina

Seperation of OPL and INL Two types typical- split at OPL reticular – split at NFL

Typical is an exaggerated form of cystoid degeneration

Reticular form split at the NFL—if there is an outer hole---may cause RD

Discontinuity in the Bruchs mem---thickened and calcified at the level of elastic layer---calcification increases brittleness of bruchs --- sub retinal neovascularisation

Seen in hemolytic anaemias , pagets, pseudoxanthoma elasticum

Lamellar or full thickness

Age related sclerosis of choriocapillaries Degeneration of the RPE—photo receptor

layer degeneration---retinal atrophy---the OLM lies almost in contact with the LAMINA VITREA

Hard drusen--- discrete round globular with overlying thinned RPE—beneath the BM of RPE—due to apoptosis of photoreceptors

Soft drusen – irregular, granular, in larger areas ---adhere loosely to the bruchs membrane

BruchBruch’’ssMembraneMembrane

BruchBruch’’ssMembraneMembrane

DrusenDrusenDrusenDrusen

ChoroidalChoroidalNeovascularizatioNeovascularizationn

ChoroidalChoroidalNeovascularizatioNeovascularizationn

Lattice like pattern of criss crossing sclerotic vessels

Focal areas of retinal thinning --- atrophic inner retinal layers--- ILM is absent---liquefied vitreous on the discontinuos membrane--- RPE hyperplasis---vitroretinal adhesions on the margins of atrophic retina---tractional retinal breaks and rhegmatogenous RD

MALIGNANT MELANOMA CHOROID

Posterior neovascularisation

Peripheral neovascularisation

Arterial macroaneurysm

PVD with retinal tear

Intra ocular tumour

Disciform degeneration

Ocular trauma CRVO