Retina

Anatomy

Fundus:

• Vitreous

• Retina

• Choroid (red)

Layers of Retina (Inside to Outside)

• Mnemonic: ING (IOP) 2
• Internal limiting membrane
• Nerve fibre layer
• Fibres collect to form optic nerve
• Ganglion cell layer
• 3rd order neurons
• Inner plexiform layer
• Inner nuclear layer
• Bipolar cells, 2nd order neurons
• Outer plexiform layer
• Outer nuclear layer
• Photoreceptors
• Rods & cones, 1st order neurons
• Pigment epithelium
• Outer blood-retinal barrier
• External limiting membrane (not visualized)

Subretinal space:

• Space between inner 9 layers & pigment epithelium.

Optic disc:

• Responsible for Blind Spot

• Diameter: 1.5 mm

• Shape: Vertical oval

• C/D ratio: 0.3

• Appears avascular.

• Located temporal to optic discs.

Ora serrata:

• Anterior termination of retina.

• Site of intravitreal injection:
• Anterior to ora serrata OR
• 3-4 mm posterior to limbus
• Pierces sclera & pars plana

Investigations

Ophthalmoscopy:

• Visualizes fundus & retina.

• 1st investigation.

Direct Ophthalmoscope:

Fundus Fluorescein Angiography (FFA):

• Visualizes fluorescent blood vessels.

• Diagnoses vascular & macular disorders.

• Normal macula appears dark.

• Pathologies show blocked/leaking blood vessels.

Indocyanine Green Angiography (ICGA):

• Visualizes choroidal vasculature.

Optical Coherence Tomography (OCT):

• Visualizes retinal layers.

• RPE always red.

• Fovea has depressed contour.

• Shows:
• Subretinal fluid collection (CSR, Retinal Detachment).
• Cystic spaces (CME).

B (Brightness) Scan USG:

• Structures observed:
• Vitreous (black/hypoechoic)
• Retina
• Choroid

• Pathologies identified:
• Vitreous Hemorrhage (white/hyperechoic).
• Choroidal melanoma
• C/F
• Metamorphosia + Painless LOV
• USG B scan: collar stud/mushroom appearance
• Angiography: Double circulation pattern

• Retinal detachment.

Vitreous Hemorrhage (VH):

• M/c causes:
• Diabetic retinopathy
• Blunt trauma (young adults)
• Eales disease (recurrent)

• Clinical feature: Blurring of vision/Loss of Vision (LOV)

• On examination: Pale fundus (red glow obscured)

Standard full-field Electroretinography (ERG):

• Records retinal action potential

• Detects photoreceptor pathology

Multifocal ERG (mfERG):

• Records cone-generated responses from central macula.

• Provides localized retinal function mapping.

• Useful for detecting macular dysfunction (early stages of macular disease).

Electrooculography (EOG):

• Records retinal standing potential

• From outer retina (photoreceptors + pigment epithelium → a+c)

• Detects photoreceptor pathology

• Measurement: Arden’s ratio = Light peak / Dark trough (Normal > 185%)

• ↓↓ in BEST’s disease

Retinoblastoma

RB gene (Retinoblastoma gene):

• Chromosome: 13q14.

• M/c inheritance: Autosomal Dominant (AD).

• Normal form: hypophosphorylated
• Mutation → Retinoblastoma.
• Phosphorylation of RB gene ("governor"):
• Phosphorylation of RB gene → RB gene inactivation → Loss of tumor suppressor function → Cell cycle don't stop at G1 phase
• Normally active
• Regulates only first checkpoint (G1-S).

• Clinical Feature
• Leukocoria

• Knudson's Two-Hit Hypothesis.
• Tumor presents only on loss of heterozygosity.

• Malignancy:
• M/c 2ndary malignancy: Osteosarcoma >>
• M/c primary malignancy: PNET/pineoblastoma

• Types of Retinoblastoma:
• Familial:
• Both eyes
• Increased risk of osteosarcoma >>> Pinealoblastoma 
  (trilateral retinoblastoma),
• Sporadic:
• More common
• One eye only.

• Mnemonic:
• Knudson was the governer →
• He lost his 2 eyes () with 2 hits (2 hit hypothesis) by an assasin
• 2 eyes represent → 2 children → 13 and 14 years old (chromosome 13,14))
• He took revenge by opening third eye (Trilateral → Pinealoblast)
• Assasin nte bone chaaramaaki (Osteosarcoma)
• Assasin → Christian (Vincristine) arrnnu, ayalde topside (etoposide) carbon (carboplatin) aakki

• Clinical Features:
• Leukocoria (M/c).
• Squint (2nd M/c).
• 2ndry glaucoma + Buphthalmos (3rd M/c).

• Spread:
• Direct through optic nerve
• ?? Hematogenous spread → Primary mode??

• CT scan (IOC):
• Shows calcified tumor.
• M/c cause of intraocular calcification.

• Biopsy (Gold standard):
• Sample: Optic nerve.
• Findings:
• Homer wright rosettes (pseudo-rosettes).
• Fleurettes.
• Flexner wintersteiner rosette:
• Empty central lumen with surrounding cells
• nucleus pointing centrally.

• Treatment: 
• B/L → TOC:
• NACT → Sx
• Enucleation (TOC)
• Removal of eyeball + optic nerve
• Chemotherapy
• Vincristine, carboplatin, and etoposide

Macular Disorders

• Macula: Responsible for central vision (due to fovea).

Tests for Macular Disorders:

• Amsler’s grid:
• Patient asked to look at central dot.
• Wavy lines indicate macular disorder.
• Straight lines indicate normal.
• Metamorphism

• Photostress test:
• Photostress recovery time
• Showing bright light to eye → bright light concentrate more on macula → depigmentation of cons → takes time to recover called photostress recovery time
• Increased photostress recovery time → macular disorder.
• Optic nerve disorders
• Normal photostress recovery time + LOV = optic nerve disease.

Central Serous Retinopathy (CSR):

• Damage to Retinal Pigment Epithelium (RPE).

• Fluid in subretinal space.

• Risk factors:
• Steroids
• Cushing’s syndrome
• H. pylori infection
• Type A personality

• Present with Central scotoma with foveal detachment

• Treatment:
• Self-resolving.
• Treat risk factor.
• Photodynamic therapy with Verteporfin
• Wet ARMD
• CSR
• Verte Porinu () pokunna CSR () with Wet Army ()
• Laser photocoagulation.
• Steroids contraindicated.

• Investigations:



• FFA
• Appearance patterns:
• Umbrella/smoke stack (CSR) – dye ascends vertically, then spreads (less common).
• Ink blot – dye leaks slowly, spreads in all directions (most common).
• OCT
• Subretinal fluid collection

1. CSR → Ceaser → Smoking and holding umbrella

2. CSR → Sub Retinal fluid collection, Self resolving, Steroids contraindicated

Cystoid Macular Edema (CME):

• Fluid in outer plexiform layer

• Inner blood retinal barrier → capillary permeability

• Mnemonic:
1. CME () arranged in OP (Outer Plexiform) about 6 (cystic space) flowers (flower petal).
2. Apo nammal star (Steroid) ayi
3. cME → Melilu Cyst
4. So we RUN with PRIDE

• Risk factors:
• Mnemonic: RUN PRIDE
• Retinitis pigmentosa.
• Uveitis.
• Niacin/nicotine.
• Prostaglandin analogues.
• Retinal vein occlusion.
• Irvine-Gass syndrome (Post-op cataract complication).
• Diabetic retinopathy.
• Epinephrine in aphakia.

• Investigations:
• Fundus
• Honeyomb apperance of macula
• FFA
• Flower petal appearance
• OCT
• Cystic spaces

• Treatment: Intravitreal steroids.

Age Related Macular Degeneration (ARMD):

Dry/Non-neovascular/Non-exudative

• Drew (Drusen) A Red (ARED S2 trial) Army (ARMD) with Brush On Skin
• (Drusen between Brusch membrane and epithelium)
• Skin became atrophy (Geographic atrophy of RPE)

• Season Look Sea (C E Zn Lu Cu Zea)

• Site of intravitreal injection:
• Anterior to ora serrata OR
• 3-4 mm posterior to limbus
• Pierces sclera & pars plana

Fundus Dystrophies

Retinitis Pigmentosa:

Triad:

• Arteriolar attenuation

• Waxy pale Optic disk

• Bony spicules

 

Mnemonic:

• Bony spicules

• Pigmentary epithelium

• Donut scotoma/tunnel vision

• Night → Nyctalopia

• Moon → Lawrence moon biedl syndrome
• Moon has law in bed

 

Features

• Rod-cone dystrophy (Rods > cones affected).

• M/c inheritance: Autosomal recessive (M/c hereditary fundus dystrophy)

• Cause: ↓↓ Docosahexanoic acid

• Clinical Features:
• Nyctalopia.
• Ring/donut scotoma/tunnel vision (rods affected).
• Bony spicule pigmentation.
• Arteriolar attenuation
• Waxy, pale optic disc.

• Systemic association:
• Lawrence-Moon-Biedl syndrome.

• Usher Sx → RP + SNHL

• Treatment:
• Genetic counselling (no specific treatment).

IOC: 

Best’s Macular Dystrophy:

• Mnemonic:
• Best (Bests MD) egg (Egg yolk lesion) undu
• See egg infront of eyes (Central scotoma) everytime
• But all family (AD) cannot eat during day time (Hemeralopia)
• Eggs are Vital (Vitelliform → Vitelliruptive lesion)
• Eggs are Less Hard (Arden’s ratio < 150%)

• Cone dystrophy

• Causes Hemeralopia (Day blindness) and central scotoma

• Autosomal dominant inheritance

• IOC: EOG (ERG normal, Arden’s ratio <150%)

• Signs:
• Egg yolk/Vitelliform lesion.
• Breaks: Pseudohypopyon/Vitelliruptive lesion

Stargardt Disease:

• kid ()→ like a fish

• Mnemonic:
• Juvenile boy (Juvenile hereditary macular dystrophy)
• Star (stargardts) → studies ABC (ABCA4 gene mutation)
• At night (bcz blind during day → Hemeralopia)
• Eat fish (fish flecks) & bulls eye (Bulls eye maculopathy)
• Everyone beat him (copper beaten on Fundus exam)
• Became Dark & Silent (dark/silent choroidal sign on FFA)

• M/c cause of Juvenile hereditary macular dystrophy

• Central scotoma

• ABCA4 gene mutation

• Day blindness: Cone >> Rod

• Fish flecks
• Seen in RPE
• Lipofuscin accumulation
• Dont give Vitamin A →
• Acclerates Lipofuscin accumulation

• Fundus sign
• Copper or silver or bronze beaten appearance
• NOTE: Copper wiring / Silver wiring → HTN Retinopathy

• FFA
• Dark choroidal sign/ silent choroidal sign

Oguchi disease

• Miss u nagamma (Mizuo Nakamura phenomenon)

• give Golden (Golden sheen) Gucci (Oguchi) bag at day
• bcz blind at night (Nyctalopia)

• Golden gucci disappears at night
• (Disappears after prolonged dark adaptation)

• Rare congenital stationary night blindness

• Autosomal recessive

• Vision
• Day vision: normal
• Night vision:severely reduced
• Reduced rod response

• Key feature
• Mizuo–Nakamura phenomenon
• Fundus:
• golden/metallic sheen in light
• Disappears after prolonged dark adaptation

Bull’s eye maculopathy

• Seen in
• Chloroquine toxicity
• Stargardt’s disease

Vascular Disorders

Diabetic Retinopathy:

• Risk factor: Duration > Glycemic control

• Screening:
• Type 1 DM: 5 years after Dx.
• Type 2 DM: Immediately on Dx.

ETDRS Classification:

• Early treatment diabetic retinopathy study

• Diabetic macular edema

Non-proliferative DR (NPDR):

• Signs: MINL (micro aneurysm → inner layer) HOPING (hemorrhage and hard exudate → OP layer) → soft cotton saree (soft exudate, Cotton wool spots) → caught fire (flame) → became nervous (Nerve fibre layer)
• Inner Nerve Layer
• Micro-aneurysms (earliest).
• OP layer
• Hemorrhages (dot & blot).
• HARD Exudates (lipid deposits).
• NFL
• Hemorrhages (flame shaped)
• Cotton wool spots (neuronal debris).

Treatment:

• Glycemic control.

• Criteria for severe NPDR

• Start VEGF
• Bro () Fly () with Rani () → after a Peg () → Bewafa ()

• Site of intravitreal injection:
• Anterior to ora serrata OR
• 3-4 mm posterior to limbus
• Pierces sclera & pars plana

Proliferative DR (PDR):

 

• Signs: Neovascularisation (NVD - at disc, NVE - elsewhere).

• Treatment: Panretinal photocoagulation > Anti-VEGF drugs.

• Mnemonic: If FFA picture is given → Identify as Proliferative

Lasers:

Principle	Laser	Uses
Photocoagulation	ㅤ	• POAG, ROP, PDR = Retina Problems
ㅤ	• Nd: YAG (532 nm) ↳ Double frequency	• Proliferative DR → Panretinal photocoagulation • Laser trabeculoplasty
ㅤ	• Argon green (514 nm)	• Rx of POAG • AG → Argon Green
ㅤ	• SLT (532 nm)	• Prophylaxis in other eye in POAG
ㅤ	• Diode red laser	• Retinopathy Of Prematurity (ROP)
Photodisruption	Disrupt Yagam	ㅤ
ㅤ	• Nd-YAG/Nd-glass	• SMILE (Myopia surgery) • Flash (FLACS) adichapo • Cap (PCO) vach Smile (SMILE) • Glass (NdGlass) vachond photodirupt () ayi.
ㅤ	• Nd-glass 1054 nm	• FLACS (Cataract Sx) → 1054 nm ↳ Femtosecond Laser ↳ Used for 2 steps 1. CCC 2. Nuclear fragmentation.
ㅤ	• Nd-YAG 1064 nm	• Posterior Capsular Opacification (PCO) / ↳ After-cataract ↳ Occurs 6-12 months postop Cataract Sx ↳ M/c complication. ↳ Elschnig’s pearls (90%) ↳ Nd-YAG posterior capsulotomy / (Peripheral Iridotomy)
Photoablation	ㅤ	ㅤ
ㅤ	• Excimer	In Psoriasis • Targeted UVB (Phototherapy) • Xenon Chloride (308 nm) In LASIK, PRK for myopia • Argon & Fluoride (193nm) • Most commonly used in refractory surgeries

 

Hypertensive Retinopathy:

• Mnemonic:
• BP kudiya aalu → Artist Salman khan
• Salman Khan in a Wagner
• Artist (Arteriolar attenuation) Salman (Salu) ne Bonnet (Bonnet) nnu gun (Gunn) eduth Kathichu (Flame) → Blood cotton (cotton wool spots) vach thudachu → Edema (Papilledema) Arum kanathirikkan silver wire (Silver wire) ketti

Keith Wagner Classification:

Note:

• Salu’s sign & Bonnet/Gunn sign
• Both are A-V changes

CRAO (Central Retinal Artery Occlusion)

• Causes: Atherosclerosis (M/c).

• Symptoms: Sudden LOV (Emergency).

• Fundus signs:
• Pale (retinal edema).
• Cattle tracking (due to blocked arteries).
• Cherry red spot at macula.

• Treatment:
• Ocular massage →
• Sublingual isosorbide nitrate (vasodilation) →
• IV mannitol →
• Aspiration of aqueous (↓IOP).

CRVO (Central Retinal Vein Occlusion):

Non-ischemic:

• Pathogenesis: Stasis → Vasodilation → Increased vascular permeability.

• Clinical Feature: Macular oedema.

• Treatment:
• Intravitreal triamcinolone
• Steroid to reduces swelling and inflammation

Ischemic:

• Tomato (Tomato splash appearance) Last 100 days (100 day glaucoma)

• Pathogenesis: Complete loss of blood supply → Cell death.

• Clinical Features:
• Severe flame-shaped hemorrhages (Tomato splash fundus)
• Iris Neovascularisation  → Rubeosis iridis
• 100 day glaucoma
• Secondary open angle glaucoma

• Treatment: Pan retinal photocoagulation.

BRVO (Branch Retinal Vein Occlusion):

• M/c affects superotemporal quadrant.

• Sectoral involvement.

Roth Spots

• Immunological phenomenon
• Oslers ( Oh... painful 😖 hand, Made into Pulp)
• Painful, red nodules on pulp of fingers and toes.
• Immune Complex mediated.

• rOths spot
• Seen in fundus with pale center (Fibrin plug).
• Caused by retinal endothelial vasculitis
• GlomerulOnephritis syndorme

Roth spot seen in

• Infective endocarditis

• Acute leukemia

Sea fan → Sickle cell retinopathy

Retinopathy Of Prematurity (ROP):

• Risk factors:
• Preterm infants <34 Wks OR <1750 grams

Born	Screen
Born ≥28wks and ≥1200g	After 4 wks of birth
Born <28wks or <1200g	Within 2-3 wks of birth

• Preterm infants 34-36 Wks gestational age + risk factors (e.g., RDS).

Stages

• Stage 1
• Formation of a demarcation line
• Separates vascular retina from avascular retina

• Stage 2
• Formation of an intraretinal ridge

• Stage 3
• Ridge with extraretinal fibrovascular proliferation
• Proliferation extends into vitreous

• Stage 4
• Subtotal retinal detachment

• Stage 5
• Total retinal detachment

Treatment:

• Laser photocoagulation (using diode red laser for NV).

• Lens sparing pars plana vitrectomy (for tractional retinal detachment).

Lasers:

Principle	Laser	Uses
Photocoagulation	ㅤ	• POAG, ROP, PDR = Retina Problems
ㅤ	• Nd: YAG (532 nm) ↳ Double frequency	• Proliferative DR → Panretinal photocoagulation • Laser trabeculoplasty
ㅤ	• Argon green (514 nm)	• Rx of POAG • AG → Argon Green
ㅤ	• SLT (532 nm)	• Prophylaxis in other eye in POAG
ㅤ	• Diode red laser	• Retinopathy Of Prematurity (ROP)
Photodisruption	Disrupt Yagam	ㅤ
ㅤ	• Nd-YAG/Nd-glass	• SMILE (Myopia surgery) • Flash (FLACS) adichapo • Cap (PCO) vach Smile (SMILE) • Glass (NdGlass) vachond photodirupt () ayi.
ㅤ	• Nd-glass 1054 nm	• FLACS (Cataract Sx) → 1054 nm ↳ Femtosecond Laser ↳ Used for 2 steps 1. CCC 2. Nuclear fragmentation.
ㅤ	• Nd-YAG 1064 nm	• Posterior Capsular Opacification (PCO) / ↳ After-cataract ↳ Occurs 6-12 months postop Cataract Sx ↳ M/c complication. ↳ Elschnig’s pearls (90%) ↳ Nd-YAG posterior capsulotomy / (Peripheral Iridotomy)
Photoablation	ㅤ	ㅤ
ㅤ	• Excimer	In Psoriasis • Targeted UVB (Phototherapy) • Xenon Chloride (308 nm) In LASIK, PRK for myopia • Argon & Fluoride (193nm) • Most commonly used in refractory surgeries

 

Retinal Detachment

• Definition: Separation of neurosensory retina from retinal pigment epithelium due to fluid collection in subretinal space.

Approach

• Curtain before eye and RAPD
• RD

• Photopsia and floaters
• Absent → Exudative
• Present → Traction or Rh

• Retinal detachment → remember → a field nilam kilakkunnath
• Exudative
• Cause: Choroidal melanoma Or Pus/Tumor
• Immobile usually, Shifting fluid, Dome shaped
• Mothalali
• Pus (exudate) olipich, malam (Choroidal melanoma) pass cheyth irikkum
• He must be shifted (shifting fluid) everywhere
• Rh
• Cause: Pathological myopia, Trauma, Surgery
• Shaffers sign (tobacco dust appearance)
• Retinal atrophy, High watermarks, Intraretinal cysts
• Retinal Break, Syeneresis, Convex, Mobile
• Shaffi (shaffers) → Use tobacco (tobacco dust) and drinks (watermark)
• Is mobile () → nashicha personality (Atrophy)
• Do sex (Convex) Perform Sins (Syeneresis)
• Scleral buckling
• External approach to seal rhegmatogenous RD
• Indentation of sclera using silicone material.
• Traction
• Cause: Diabetic retinopathy
• Diabetic, Demarcation line, Tent shaped
• Concave, immobile, Taut, Fibrous bands
• Diabteic (Diabetic retinopathy) old man → but good taut (immobile - taut) demarcated (demarcation lines) muscles with

Investigations:

• IOC: Indirect ophthalmoscopy

• OCT shows subretinal fluid collection

• 2 Workers in field
• 1st
• 2nd →

Chloroquine Toxicity Manifestations

• Erythema Multiforme

Chloroquine Toxicity	Ocular Manifestations
1. Pre-Maculopathy	ㅤ
↳ Early /Reversible	• Normal vision (peripheral) • Central scotoma (blind spot)
2. Maculopathy	ㅤ
↳ Advanced / Irreversible	• Bull's eye lesion maculopathy • ↓↓↓ visual acuity hit Bulls eye (Bulls eye maculopathy) when u get the Queen (Chloroquine)

Bull's eye lesion maculopathy

---

• Seen in
• Chloroquine toxicity
• Stargardt’s disease

---

Vortex Keratopathy / Cornea verticillata

• Whorl like/Spindle pattern

• Also seen in Queen () Ami () Tame () with Netram () in Indian () Fabric () dress
• Chloroquine
• Amiodarone
• Tamoxifene
• Netarsudil (Rho kinase ⛔),
• Indomethacin
• Fabry’s disease
• Phenothiazines

• NOT Methotrexate