Retinal Detachment

Retinal detachment (RD) is the separation of the neurosensory retina (NSR) from the underlying retinal pigment epithelium (RPE), with accumulation of subretinal fluid (SRF) in the potential space between them. This space is an embryological remnant of the optic vesicle cavity, which explains why the two layers are only loosely apposed and why detachment is mechanically possible. Once separated, the photoreceptor outer segments lose their metabolic and nutritional support from the choriocapillaris (which supplies the outer retina), and irreversible photoreceptor death begins within days to weeks — making RD a vision-threatening ocular emergency, especially when the macula is still attached ("macula-on").

For NEET PG, RD is a favourite high-yield topic because it neatly tests mechanism-based classification. The single most important first step in any RD question is to decide which of the three types you are dealing with — rhegmatogenous, tractional, or exudative — because the etiology, fundus appearance, investigation, and management all flow from that decision. This note builds that framework systematically.

Types / Classification

There are three pathophysiological types of retinal detachment. The mnemonic "RTE" (Rheg, Traction, Exudative) captures all three.

Feature	Rhegmatogenous (RRD)	Tractional (TRD)	Exudative / Serous (ERD)
Mechanism	Retinal break + vitreous fluid entry	Vitreoretinal traction pulls retina off	Fluid leaks from choroid/RPE without break
Break present	Yes (defining feature)	No (unless combined)	No
Commonest type	Yes – most common overall	Second	Least common
SRF shifting	No (fixed by gravity but configuration stable)	No	Yes – shifting fluid is classic
Surface	Convex, corrugated, mobile, undulating	Concave, taut, immobile, tented at traction point	Convex, smooth, bullous
SRF	Clear	Minimal	Turbid, shifts with head position
Pigment in vitreous	Tobacco dust (Shafer sign)	Absent	Absent
IOP	Usually low	Normal/low	Normal or raised (tumour)
Treats by	Closing the break (surgery)	Relieving traction (vitrectomy)	Treating the underlying cause

High-yield: "Rhegma" is Greek for break/rent. The presence of a full-thickness retinal break is what makes a detachment rhegmatogenous — this is the most common type and the one classically operated upon.

Rhegmatogenous RD (RRD)

A full-thickness retinal break allows liquefied vitreous to pass through into the subretinal space, peeling the NSR off the RPE. Breaks are classified as:

• Tears (horseshoe / U-shaped / flap tears): caused by dynamic vitreous traction; the flap points toward the posterior pole. Highest risk of progression.
• Holes (round/atrophic): caused by retinal atrophy (e.g., lattice degeneration); lower risk.
• Dialysis: circumferential break at the ora serrata, classically inferotemporal, typical of young patients post-trauma.
• Giant retinal tear (GRT): extends ≥ 90° (3 clock hours) circumferentially.

Tractional RD (TRD)

Fibrovascular or fibrocellular membranes contract and physically pull the retina away. The surface is concave and immobile. Causes are dominated by proliferative diabetic retinopathy (PDR).

Exudative (Serous) RD (ERD)

Breakdown of the blood-retinal barrier at the level of the RPE/choroid lets fluid accumulate subretinally without any break or traction. Hallmark is shifting subretinal fluid that gravitates to the dependent retina with head position. Underlying causes are inflammatory, vascular, or neoplastic.

Etiology & Risk Factors

The dominant risk factor for RRD is posterior vitreous detachment (PVD). With age, the vitreous gel liquefies (syneresis) and collapses, separating from the retina; where vitreoretinal adhesion is strong (e.g., over lattice), this traction tears the retina.

Type	Key etiologies / risk factors
Rhegmatogenous	Myopia (axial elongation, lattice degeneration), aphakia/pseudophakia (post-cataract surgery), PVD, trauma, lattice degeneration, fellow-eye RD, Stickler/Marfan syndrome, prior intraocular surgery
Tractional	Proliferative diabetic retinopathy (commonest), retinopathy of prematurity (ROP), sickle cell retinopathy (proliferative), retinal vein occlusion with neovascularisation, penetrating trauma, PVR
Exudative	Coats disease, choroidal tumours (malignant melanoma, choroidal metastasis, retinoblastoma), VKH (Vogt-Koyanagi-Harada), posterior scleritis, central serous chorioretinopathy, toxaemia of pregnancy (HELLP/eclampsia), malignant hypertension, nanophthalmos

High-yield: Myopia + lattice degeneration + PVD is the classic triad predisposing to rhegmatogenous RD. Lattice degeneration is present in ~30% of RRD eyes. Always examine the fellow eye — bilateral predisposition is the rule.

High-yield: In a child with a white pupillary reflex (leukocoria) and exudative RD, the two must-not-miss diagnoses are retinoblastoma (malignant, life-threatening) and Coats disease (telangiectatic vessels with lipid exudation). Distinguishing them is a recurring exam theme.

Clinical Features

The classic symptom sequence of RRD follows the underlying PVD and break:

Flashes of light (photopsia) → Floaters (sudden shower) → Curtain / veil over field → Painless loss of vision

• Photopsia (flashes): mechanical stimulation of the retina by vitreous traction; often described in the temporal periphery.
• Floaters: sudden onset, especially a "shower" of new floaters or a "cobweb," suggests a break with vitreous haemorrhage or pigment release. A single large floater may represent a Weiss ring (annular condensation around the optic disc — sign of PVD).
• Field defect / curtain: a relative scotoma that progresses. A superior field defect implies an inferior detachment and vice versa (the image is inverted). The defect advancing toward fixation signals approaching macular involvement.
• Central vision loss / metamorphopsia: occurs once the macula detaches ("macula-off") — visual prognosis worsens sharply after this point.

Exudative RD by contrast tends to present with painless visual disturbance plus features of the underlying disease (uveitis, headache, hypertension), and the field defect can shift with posture. Tractional RD is often slowly progressive and asymptomatic until the macula is involved.

High-yield: Photopsia and floaters = symptoms of the break/PVD; a curtain coming across the vision = the detachment itself. Any patient with a sudden shower of floaters and flashes needs urgent dilated indirect ophthalmoscopy to rule out a retinal break.

Fundus / examination findings

• Indirect ophthalmoscopy with scleral indentation is the cornerstone — it gives a wide, stereoscopic, peripheral view.
• RRD: grey/translucent, convex, corrugated, undulating retina that moves with eye movement; one or more breaks (red against the detached grey retina).
• TRD: concave, taut, tented retina, immobile, dragged toward fibrovascular tissue.
• ERD: smooth, bullous, convex elevation; shifting fluid; no break.
• Shafer's sign (tobacco dust): pigment granules (liberated RPE cells) in the anterior vitreous — strongly indicates a retinal break.
• A Tulip / Lincoff's rules help localise the primary break based on the configuration of the SRF.

Investigation of Choice

Scenario	Investigation of choice
Suspected RRD, clear media	Dilated indirect ophthalmoscopy with scleral depression (gold standard for finding breaks)
Hazy media / vitreous haemorrhage / dense cataract (cannot see fundus)	B-scan ultrasonography
Macular status / SRF / membrane assessment	Optical coherence tomography (OCT)
Suspected exudative RD from tumour	B-scan + fluorescein angiography; MRI if retinoblastoma/melanoma
Documenting break and following progression	Fundus drawing / wide-field fundus photography

High-yield: When you cannot see the retina (vitreous haemorrhage, mature cataract, hyphema), the investigation of choice for RD is B-scan ultrasonography. RRD shows a mobile, often "V"-shaped membrane tethered to the optic disc and ora; total RD is "funnel-shaped." It also detects an underlying tumour in exudative RD.

Management / Surgical Options

The treatment principle is type-specific: close the break (RRD), relieve traction (TRD), or treat the cause (ERD).

Prophylaxis (before detachment)

A retinal break, lattice, or symptomatic horseshoe tear without detachment is treated prophylactically to seal it:

• Laser photocoagulation (argon/green laser barrage around the break), or
• Cryotherapy (cryopexy) for peripheral lesions. These create a chorioretinal adhesion (scar) that walls off the break.

Surgery for established RRD

There are three principal procedures; choice depends on break number, location, lens status, and PVR grade.

Procedure	Principle	Best for	Notes
Pneumatic retinopexy	Intravitreal gas bubble (SF6/C3F8) tamponades break + laser/cryo; patient positions head	Single break in superior 8 clock hours, phakic, no significant PVR	Office procedure; posturing critical; lowest invasiveness
Scleral buckling (SB)	Silicone explant/band indents sclera to bring RPE to the break and relieve traction; drain SRF ± cryo	Young phakic eyes, inferior/multiple breaks, lattice; classic for dialysis	May cause myopic shift (axial length increase), diplopia, extrusion
Pars plana vitrectomy (PPV)	Remove vitreous, relieve traction, drain SRF internally, endolaser, tamponade with gas or silicone oil	Pseudophakic/aphakic, GRT, posterior breaks, media opacity, PVR, combined RD	Often combined with SB; silicone oil needs later removal

• Tamponade agents: gases (SF₆ ~2 weeks, C₃F₈ ~6–8 weeks) and silicone oil (long-term). Gas expands and is contraindicated for air travel / nitrous oxide anaesthesia until absorbed.
• Retinopexy (laser or cryo) is the step that permanently seals the break in every approach.

High-yield: Scleral buckling is the classic operation for retinal dialysis in young patients and for inferior breaks; pneumatic retinopexy suits a single superior break; vitrectomy with silicone oil is preferred for complicated RRD with PVR, giant tears, or media opacity.

Tractional RD

• Pars plana vitrectomy with membrane delamination/segmentation to relieve traction; endolaser to ischaemic retina; anti-VEGF pre-op (e.g., in PDR) reduces bleeding. Operate when traction threatens or involves the macula.

Exudative RD

• Treat the underlying disease — there is no break to close. Examples: systemic/local corticosteroids for VKH/posterior scleritis, laser/cryo for Coats disease telangiectasia, control of malignant hypertension/toxaemia, and tumour-directed therapy (plaque brachytherapy, enucleation) for melanoma/retinoblastoma. Surgery on the retina itself is usually not indicated.

High-yield: Never "buckle" or vitrectomise an exudative RD blindly — fix the cause. Operating on an undiagnosed choroidal melanoma is a disaster.

Complications

• Proliferative vitreoretinopathy (PVR): the leading cause of failed RD surgery and re-detachment. Cellular proliferation (RPE, glia) forms contractile membranes causing fixed retinal folds and traction. Graded A–D (Retina Society classification).
• Re-detachment requiring repeat surgery.
• Macula-off → permanent central vision loss / metamorphopsia even after successful reattachment.
• Cataract (after vitrectomy, gas, or silicone oil — nearly universal in phakic vitrectomy).
• Raised IOP / glaucoma (gas expansion, silicone oil, steroids) or hypotony / phthisis bulbi in chronic total RD.
• Endophthalmitis (any intraocular surgery).
• Buckle-specific: myopic shift, diplopia/strabismus, explant infection or extrusion, anterior segment ischaemia.
• Choroidal detachment, vitreous haemorrhage, epiretinal membrane / macular pucker, cystoid macular oedema.

Differentials

A "retinal elevation" is not always a true RD. Distinguish from:

• Retinoschisis (degenerative): splitting within the retina (outer plexiform layer), smooth, dome-shaped, immobile, absolute scotoma, no Shafer sign, no progression to macula usually. Contrast with RD's relative scotoma and corrugated mobile surface.
• Choroidal detachment / effusion: smooth, solid, brown, does not undulate; often post-op with hypotony.
• Choroidal mass / melanoma / metastasis: solid elevation; the cause of many exudative RDs.
• Among the three RD types: the table at the top resolves rhegmatogenous vs tractional vs exudative — anchored on break (RRD), concave taut surface (TRD), shifting fluid (ERD).

Distinguishing feature	Retinal detachment	Retinoschisis
Scotoma	Relative (progresses)	Absolute
Surface	Convex, corrugated, mobile	Smooth, dome, immobile
Break	Often present (RRD)	Inner/outer layer holes only
Shafer sign	May be present	Absent
Photopsia	Present	Usually absent

Recently asked / exam angle

• "Tobacco dust / Shafer sign" → retinal break / RRD is a repeated single-best-answer pickup.
• Investigation of choice when media are hazy → B-scan ultrasonography. Frequently framed as "RD with vitreous haemorrhage."
• Concave, taut, immobile retinal surface → tractional RD (think PDR / sickle cell).
• Shifting subretinal fluid → exudative RD; then identify the cause (Coats, VKH, tumour, toxaemia).
• Scleral buckling for retinal dialysis in a young trauma patient is a classic management single-best-answer.
• Inferotemporal dialysis is the commonest location/type of traumatic RD break.
• Pneumatic retinopexy = single superior break, phakic. Image-based and management MCQs both test this.
• Macula-on vs macula-off as a determinant of urgency and prognosis.
• Leukocoria differentials in a child (retinoblastoma vs Coats) presenting as exudative RD.
• PVR as the commonest cause of surgical failure / redetachment.
• Assertion-reason: "Superior field defect implies inferior retinal detachment" (image inversion) — true.

Rapid revision

• Three types: Rhegmatogenous (break), Tractional (traction, concave), Exudative (shifting fluid). RRD is commonest.
• RRD driven by PVD + myopia + lattice degeneration; always check the fellow eye.
• Symptom march: flashes → floaters → curtain → painless vision loss.
• Shafer's sign (tobacco dust) = retinal break until proven otherwise.
• Gold standard exam = indirect ophthalmoscopy with scleral indentation; hazy media → B-scan USG.
• Concave + taut + immobile = tractional (PDR, ROP, sickle cell).
• Shifting subretinal fluid + smooth bullous surface = exudative (Coats, VKH, melanoma, toxaemia).
• Scleral buckling = young, phakic, inferior/dialysis breaks; risk = myopic shift.
• Pneumatic retinopexy = single break in superior 8 clock hours, phakic.
• Vitrectomy + tamponade (gas/silicone oil) = PVR, giant tears, media opacity, pseudophakic.
• Gas tamponade: SF₆ ≈ 2 wk, C₃F₈ ≈ 6–8 wk; avoid air travel/nitrous oxide with intraocular gas.
• PVR = leading cause of redetachment; macula-off = poorer visual prognosis — operate before the macula goes.
• Exudative RD: treat the cause, do not buckle/vitrectomise blindly.
• Mimics: retinoschisis (absolute scotoma, immobile) and choroidal detachment/mass.