Diseases of Retina

ANATOMY:

Innermost, delicate, transparent, purple red[rods], highly developed tissue of eye. 3 regions:

1. OPTIC DISC:
   • pink, defined circle of d=1.5mm
   • nasal to posterior pole
   • physiologic cup is the central depression where retinal bv emerge.
   • all retinal layers except nerves[which enter lamina cribrosa] terminate.
2. MACULA / YELLOW SPOT:
   • 5.5mm dark area at posterior pole.
   • central depression =1.5mm is fovea with shiny foveola which is the most sensitive part of retina & is 2discs temporal + 1mm inferior.
3. ORA SERRATA: firmly attached to vitreous & choroid.

FOVEA has only tightly packed cones [no rods] & other layers are thin. Cone axons are obliquely arranged in HENLE’s outer plexiform.
FOVEOLA has only cones & its nuclei without any other layers.

Blood supply	Layers
Choroidal bv [supply outer 4 layers]	Pigment epithelium [firmly adherent to choroid's BRUCH] Photoreceptor processes Fenestrated external LM Outer nuclear [rods&cones]
Central Retinal bv emerges from cup, devides into 4 end arteries [superior -nasal&temporal, inferior -nasal&temporal] [supply inner 6 layers]	Outer plexifrom Inner nuclear [Bipolar(1st order neurons), Horz, Amacrine] Inner plexiform Ganglion(2nd order neurons) Nerve fibre /stratum opticum [ganglion cells axons pass thr lamina cribrosa to form Optic.N] Internal LM

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Congenital disorders:

COLOBOMA

embryonic fissure closure failure

minor defect presents as inferior crescent

major defect usually presents as inferonasal

DRUSEN

waxy pea-like refractile bodies [initially deep underneath presenting as pseudo-papilloedema]

HYPOPLASIA

small disc with yellow double ring sign.

associated with maternal use during pregnancy- alcohol,DM, drugs.

MEDULLATED / MYELINATED nerve fibres

fetahery margined white patch around optic disc

due to myelination beyond cribrosa

enlarge the blind spot

disappear in demyelinating disorders

PERSISTANT HYALOID ARTERY

Bergmester’s papilla projecting from optic disc

Vascular loop running in vitreous

Mittendorf dot attached to posterior lens capsule [associated posterior polar cataract]

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Inflammatory disorders of retina

• retinitis
• retinal-vasculitis can be primary[EALE's] or secondary to uveitis
• chorio-retinitis
• neuro-retinitis

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Vascular disordes of retina

Retinal artery occlusion

ETIOLOGY

• thrombosis, embolism
• vasculitis [PAnodosa, scleroderma]
• angiospasm [amaurosis]
• raised IOP [acute angle closure glaucoma, in tight encirclage in retinal detachment surgery

CFs

obstruction at the level of cribrosa [CRAO] or at bifurcation [br.A occlusion causing symtoms distally]

symptom- painless sudden vision loss

signs-

• absent direct pupil light reflex
• narrowed retinal arteries but normal veins with cattle track segmented appearance.
• initially milky edematous retina & wks later atrophies.
• cherry red spot in macula due to shinning of vascular choroid thr thin retina

Rx -unsatisfactory due to life of retina<6hrs. Emergency management:

• lower IOP with mannitol, massage, paracentasis.
• vasodil, CO2 for relieving angiospasm
• anticoag for thrombi
• steroids for vasculitis

Retinal vein occlusion

more common than artery occlusions

affects elders>50

ETIOLOGY

• sclerotic retinal artery pressure
• increased blood viscousity
• periphlebitis
• raised IOP in open angle glaucoma
• local causes like orbital cellulitis, cavernous sinus thrombosis.

Non-ischaemic CRVO venous stasis retinopathy [most common]	Ischaemic CRVO Haemorrhagic retinopathy
mild vision loss mild congestion peripheral superficial flame hmrrg mild papilledema	sudden marked vision loss massive congestion massive hmrrg giving splashed tomato appearnace to whole fundus papilledema, soft exudate macula is involved
Late symptoms: sheathing of veins & collaterals partially absorbed hmrrg moderate cases show chronic cystoid macular edema which causes permanent vision loss. [Rx-steroids]	Late symptoms: marked sheathing of veins & collaterals neovascularization macula shows pigmentary changes & chronic cystoid edema
Rx: 50% cases resolve spontaneously	Rx: photocoagulation to prevent neovascular glaucoma

Hypertensive retinopathy

Pathogenesis – fundus changes due to systemic hypertension

1. retinal arteriolar vasoconstriction – related to severity of sysHTN. Occurs in young & affected by involutional sclerosis in old.
2. arteriosclerosis [wall thickening / narrow lumen causes arteriolar light reflex & A-V nipping] – related to duration of sysHTN. Occurs in old due to involutionary sclerosis.
3. Increased vascular permeability [superficial hmrrg, exudates (reversible soft=cotton-wool spots; lipid hard with macular star), focal edema] – due to hypoxia.

Grading -

1	mild general arteriolar attennuation + tortousity with broadening of arteriolar light [silver-wiring]& vein concealment.
2	marked general arteriolar vasoconstriction with A-V nipping [Salu's sign]
3	in addition to Grade2 changes: arteriolar copper wiring distal veins banking [Bonnet sign] vein tappering on either side of A-Vcrossing [Gunn sign] flame hmrrg, cotton-wool spots, hard exudates.
4	Grade3 changes + papilledema

Clinical types:

SysHTN with Senile/involutionary sclerosis	old age augmented arteriosclerotic retinopathy
SysHTN without sclerosis	young with short duration HTN pale staright constricted arterioles with acute angled branching [tortous]
SysHTN with compensatory nehrosclerosis	young with prolonged HTN proliferation & fobrosis of arteriolar media adbanced changes – albuminuric/renal retinopathy
Malignant HTN / Non-compensated nephrosclerosis	young with prolonged HTN papilledema marked areteiolar narrowing flame hmrrg, cotton wool spots.

Retinopathy in PIH:

PIH= HTN, proteinuria, anasarca

retinal changes seen if >160/100

CFs:

nasal arteiolar narrowing, later generalised.

hypoxia from severe persistant spasm causes cotton-wool spots & superficial hmrrg

continued pregnancy causes rapid progression to retinal edema & exudation may be with macular star[discrete hard lipid deposits in macular edema] or flat macular detachment.

Management:

pre-organic changes are reversible after delivery.

terminate pregnancy with hypoxic retinopathy to prevent permanent visual loss.

Diabetic retinopathy

Pre-disposers:

• DM duration irrespective of blood glucose levels – 90% dev after 30yrs, 50% after 10yrs.
• females, pregnancy accelarates.
• hereditary esp for PDR
• HTN

Pathogenesis:

DM causes micro-vascular occlusion by:

• thickening BM
• endothelial damage
• RBC changes & making Plts sticky

occlusion in retinal bv causes retinal ischaemia signs-

• microaneurysms
• hmmrrges
• edema
• hard exudates
• A-V shunts
• neovasclrztn

Clinical types:

1. NPDR:
   • macular microaneurysms [VERY MILD NPDR]
   • hmmrges – deep dot & blot/infarcts , superficial flame
   • hard exudates – waxy yellow-white patches arranged in clumps or circinate pattern.
   • [above 3 signs inMILD NPDR (1,2quadrants); MODERATE NPDR (2,3quadrants)]
   • edema
   • [inaddition to above signs, the following are seen in any 1 in SEVERE NPDR & >2 in VERY SEVERE NPDR]
     • cotton-wool spots [>8mm risk of PDR]
     • venous beading, loops, dilatation
     • AV shunts
2. D.maculopathy: affects vision when there is clinically significant macular edema [due to increased permeability] which meets atleast 1criteria
   1. edema within 500microns from foveola
   2. hard exudates within 500microns from foveola
   3. =/>1disc edema, part of which is within 1disc of foveola

   Flourescein angiography TYPES:

   1. Focal exudative (focal leak) : microaneurysms, hmrrges, macular edema, hard exudates (circinate).
   2. Diffuse exudative (diffuse leak) : diffuse edema, few hard exudates.
   3. Ischaemic (early changes- enlarged foveal avascular zone & capillary dropouts, adv changes- blocked precapillary arterioles) : marked visual loss, microaneurysms, hmrrges, mild macular edema, few hard exudates.
   4. Mixed {ischaemic + exudative}
3. PDR: common in juvenile onset DM.
   • very severe NPDR
   • neovasculrztn [esp temporal - NVD, NVE] – high risk PDR if
     • NVD <1/4disc +/- VH/PRH
     • NVD 1/4 + VH/PRH
     • NVE >1/2 + VH/PRH
   • adv – fibrovascular epiretinal membrane around noevascl due to CT condensation.
4. ADED : due to uncontrolled PDR
   • VH
   • Tractional RD
   • neovascl Glaucoma

Diagnosis:

urine ex, blood glucose levels, fundus flourescein angiography[neovascl, leak, non-pefusion]

Rx:

• strict blood glucose control
• HTN control
• yearly screening [modNPDR -6mos; severeNPDR -3mos; non-high riskPDR -2mos]
• photocoagulation (CI in ischaemic) -
  • panretinal – high risk PDR
  • grid – diffuse macular edema
  • focal – focal exudative Mculopathy
• pars plana vitrctomy – epiretinal membrane,ADED [VH, RD]

Retinopathy of prematurity [ROP]

Etiology-

premature infants[<1.3kg] exposed to high[>30%] oxygen conc in first 5-10wks of life.

Pathogenesis-

bilateral proliferative retinopathy – obliteration followed by neovascl & retrolental fibroplasia.

CFs – 5stages	Rx
1 – demarcation line between vascular & avascular retina.	spontaneous regression in 80-90%cases.
2 – line acquires volume to form a ridge	spontaneous regression in 80-90%cases
3 – extra-retinal fibrovascular proliferation into vitreous	cryo/laser
4 – subtotal retinal detachment from exudate from incompetent bv or fibrous tissue traction a- not involving macula b- involves macula	a- buckling b- vitrectomy
5 – total retinal detachment [funnel]	vitrectomy
3 retinal zones with optic disc as centre:	circle with r= 2times disc-macula distance; severe due to peripheral avascularity inbetween zone when circle is drawn with r=disc-nasal oraserrata. remaining temporal arc outside zone2.
PLUS disease	zone1 with torous dilated bv
RUSH	PLUS + iris neovasclrtn
THRESHOLD	PLUS in 5continous or 8discontinous clock hrs.

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Common retinal dystrophy – RETINITIS PIGMENTOSA

• primary / hereditery – appears in childhood, insidiously progresses to blindness by middle-age.
• pigmentary [rods>cones]
• bilaterally equal
• males

CFs:

symptoms-

• early charecteristic is NIGHT-BLINDNESS due to degeneration of rods.
• increased threshold for dark adaptation.
• tunnel vision n late stage finally lending in blindness.

signs-

• perivacular pigmentary changes resembling bone corpuscles -initially equatorial, later ant&post
• narrow arterioles
• adv – pale waxy disc, optic atrophy.
• Visual field – anular scotoma initially corresponding to eq, later ant&post.
• early ERG changes.

Rx: unsatisfactory.

management with low vision aids

check regression with vasodil, placental extracts, rectus transpltn, light exclusion therapy, vitAE.

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MACULAR DISORDERS

Photoretinitis / solar / eclipse burn

etiology-

IR rays of bright sunlight [or by directly watching sun during eclipse] gets absorbed by pigment eoithelium causing foveola burn.

CFs-

persisting negative after-image of sun progressing later to positive scotoma & metamorphopsia

late sign – macular hole [kidney shaped pigmented spot with yellow-white fovea] & surrounding mottled pigmentation.

Prognosis – guarded since some visual acuity loss mostly persists.

Central serous retinopathy

spontaneous detachment of neurosensory retina in macula due to fluid collection from pigEpi defect.

CFs-

• sudden painless vision loss, positive scotoma, metamorphopsia, micropsia.
• mild macular elevation demarcated by circular ring reflex. Distorted foveal reflex.
• self-resolution after 3wk-1yr may leave small areas of atrophy & pigment changes.

Dignosis- flourescein angiography pattern

• Ink blot – later increass in sige.
• smoke stack – later expands as mushroom cloud.

Rx-

• spontaneous resolution within 3wks-1yr in 80%cases.
• laser photocoagulation – when marked vision loss >4mos, recurrent with vision loss, permanet vision loss in other eye due to CSR.

Cystoid macular edema

fluid collection in henle’s outer plexiform layer around foveola due to innerBRB capillary leak, associated with many disorders:

• post-operative complication of cataract extraction,keratoplasty
• retinal vascular disorders & dystrophies
• uveitis
• adrenaline drops

CFs-

• moderate vision loss
• honey-comb appearance of macula
• flower-petal appearance of macula with flourescein.

Rx-

prophylaxis with anit-PG drops, steroids may help.

Age-related Macular degeneration

bilateral senile macular degeneration

leading cause of blindness in developed countries in age>65yrs.

NON-EXUDATIVE / DRY	EXUDATIVE / WET / NEOVASCULAR
90% ARMD mild visual loss	10%ARMD rapidly progressive marked vision
drusens [colloid bodies] – small discrete yellow-white elevated spots. geographic – pale atrophied pigEpi& irregular / clustered pigmentation.	choroidal neovasc hmmrrgic retinal detachment disciform scarring macular degeneration
Rx is not effective.	Rx : photocoagulation for extrafoveal choroidal neovascl to prevent further vision loss.

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Retinal detachment

neurosensory layer separation from pigEpi in retina.

Primary / Rhegmatogenous

prdisposers: senile posterior viteous detachment peripheral retinal degenerations aphakia myopia trauma

cause retinal tears

causes rapid degeneration of sub-retinal vitreous which sweeps in & separates layers.

CFs-

prodromal symtoms – dark spots, photopsia.

localised visual field loss usually in upper temporal, which progresses to total loss when macula gets involved or sudden painless vision loss due to large central detachment.

signs-

• grey pupil reflex
• raised retina with oscillating folds or funnel shaped total detachment.
• red breaks in upper temporal- round / horseshoe / slit / large anterior dialysis

scotomas & ERG changes

Diagnosis- ultrasonography esf if media is hazy

Rx-

• seal breaks with photo/cryo-coagulation to produce asceptic sclerochoroid.
• scleral buckling/encirclage to reattach retina to sclerochoroid.

Complications in log-standing cases-

• proliferative vireo-retinopathy
• complicated cataract
• uveitis
• phthisis bulbi

Secondary RDs:

Exudative / solid

etiology -retina is pushed away by fliud/neoplasm

• systemic causes – PIH, renal HTN, blood dyscrasias, PAnodosa.
• ocular causes- neop[lasms, inflm & vascular disorders, sudden hypotony from perforation.

CFs- smooth, convex

• shifting fluid withh gravity
• fixed on tumor +/- pigment/neovascl.

Rx- spontaneouly regresses after fluid absorption or tumor enucleation.

Tractional

etiology - vitreo-retinal traction band contraction

• post-traumatic scar
• proliferative diabetic retinopathy, eale's proliferative retinopathy
• post-hmmrgic retinitis proliferans, sickle cell retinopathy
• ROP

CFs-

• vitro-retinal bands with causative lesion
• concave detached area.

Rx- buckling + vitrectomy for bands & internal tamponade.

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Retinoblastoma

most common intraocular tumor of childhood.

congenital neurosensory tumor due to malignant proliferation of retinoblasts [small round cells with large nuclei] which can be

• undifferentiated
• well-differntiated – Flexner-wintersteiner rosette, Homer-wright rosette
• lesion may also show necrosis & calcification.

noticed at age 1-2yrs

unilateral[sporadic cases - 94%], bilateral [familial cases]

4stages:

1. QUIESCENT [lasts 6mos-1yr]-
   • leucoria/amaurotic cat’s eye reflex.
   • convergent squint
   • nystagmus in bilateral cases
   • early tumor growth before leucoria
     • endophytic into vitreous – polyploid, white/pink, cottege cheese like if calcification.
     • exophytic separating retina from choroid.
2. Glaucomatous-
   • severe pain
   • hazy cornea
   • conj redness
   • watering
   • apparent proptosis, raised IOP.
   • masquerading as iridocyclitis.
3. Extraocular extension- rapid fungation into extraocular tissues 7 globe bursts usually at limbus & there is marked proptosis.
4. Metastasis to preauricularLN, contigousspread to opticN & brain, thr blood to bones.

Diagnosis -

• ophthalmoscopy [anaesthesia+mydriasis]
• IOP measurement
• corenal diameter
• Xrays can detect calcification
• raised LDH in AqH
• ultrasonography

Rx-

• early 1stage [<10mm, OpticN uninvolved] – radiotherapy, photocoagulation, cryotherapy.
• late 1 & 2 stages – enucleation & radio+chemo for nerve involvement.
• 3&4 stages – debulking + radio&chemotherapy.
• poor prognosis if nerve & choroid involvement, undifferentiated tumor cells. Hence enucleation before extraocular extension.
• spontaneous regression from necrosis & calcification

D/D of leucoria[yellow-white pupil reflex] causes [PSEUDOGLIOMA] apart from Retinoblastoma:

• congenital cataract
• inflm deposits[uveitis] in vitreous
• toxocara endophthalmitis
• choroid coloboma
• ROP
• exudative retinopathy of coats
• persistant hyperplastic primary vitreous.