Rhegmatogenous retinal detachment for 15 marks
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Rhegmatogenous Retinal Detachment (RRD)
Definition
Rhegmatogenous retinal detachment (from Greek rhegma = rent/break) is a separation of the neurosensory retina from the retinal pigment epithelium (RPE) through a full-thickness break in the retina, allowing liquefied vitreous to accumulate in the subretinal space.
Epidemiology & Pathogenesis
- Incidence: ~1 in 10,000 per year; bilateral involvement in ~10% of cases
- Pathogenetic triad: retinal break + vitreous liquefaction (syneresis) + vitreoretinal traction
- RD almost never occurs if vitreous is not at least partially liquefied and traction is absent
- >40% of RDs occur in myopic eyes — high myopia causes vitreous degeneration, PVD, and lattice/snailtrack degeneration more commonly
- Highly myopic eyes also face risk from round holes in chorioretinal atrophy and macular holes
- Vitreous loss at cataract surgery and Nd:YAG laser capsulotomy also increase risk
Types of Retinal Breaks
| Type | Mechanism | Features |
|---|---|---|
| U-tear / horseshoe tear | Dynamic vitreoretinal traction during PVD | Flap remains attached anteriorly; most common cause of RRD |
| Round/oval hole | Atrophic degeneration (no traction) | Common in lattice degeneration, young myopes |
| Dialysis | Avulsion at ora serrata | Post-traumatic; slow-spreading inferior RD |
| Giant tear | >90° circumferential break | Severe PVD; high risk of PVR |
Risk Factors
- High myopia
- Previous cataract surgery / aphakia / pseudophakia
- Lattice degeneration, snailtrack degeneration
- Blunt ocular trauma
- Fellow eye RD (contralateral RD risk ~10%)
- Family history
Distribution of Breaks
- ~60% superotemporal quadrant
- ~15% superonasal
- ~15% inferotemporal
- ~10% inferonasal
- ~50% of eyes with RD have more than one break, often within 90° of each other
Modified Lincoff's Rules (SRF Spread)
SRF spread is governed by gravity, anatomical limits (ora serrata, optic nerve), and the location of the primary break.
Key rules:
- Superior break → SRF spreads inferiorly on same side first, then superiorly opposite
- Inferior RD slightly higher on temporal side → break on that side inferiorly
- Break at 6 o'clock → equal fluid levels inferiorly
- Bullous inferior RD → primary break usually above horizontal meridian
- Subtotal RD with superior wedge of attached retina → break at periphery nearest its highest border
Symptoms
Classic premonitory symptoms occur in ~60% of patients with acute PVD:
- Photopsia (flashing lights) — due to vitreoretinal traction (location of photopsia does NOT predict break site)
- Floaters — due to PVD, vitreous condensation, or tobacco dust
- Curtain/shadow — relative peripheral visual field defect; appears in the quadrant opposite to the primary break
- Loss of central vision — if fovea involved by SRF, or by large bullous RD
- A lower field defect is appreciated more quickly than an upper defect
The quadrant of the field defect first appearing is opposite to the primary break location.
Signs
General
- Relative afferent pupillary defect (RAPD/Marcus Gunn pupil) — in extensive RD
- Low IOP (~5 mmHg lower than fellow eye) — characteristic
- Very low IOP + associated choroidal detachment
- Raised IOP → Schwartz-Matsuo syndrome (RRD + apparent uveitis, often dialysis from blunt trauma; displaced photoreceptor outer segments clog trabecular meshwork — resolves after RD repair)
- 'Tobacco dust' (Shafer's sign) — pigment cells in anterior vitreous; highly specific for RRD
- Mild iritis — common; may mask underlying RD
Fundus — Fresh RD
- Convex elevation of retina with slightly opaque, corrugated appearance (retinal oedema)
- Loss of underlying choroidal pattern
- Retinal blood vessels appear darker than in flat retina
- SRF extends to ora serrata
- B-scan US: good mobility of retina and vitreous
Fundus — Longstanding RD
- Retinal thinning (atrophy)
- Intraretinal cysts — develop after ~1 year; resolve after reattachment
- Subretinal demarcation lines ('high-water marks' or 'tide marks') — RPE cell proliferation at junction of flat/detached retina; develop after ~3 months
Differential Diagnosis
| Condition | Distinguishing Features |
|---|---|
| Retinoschisis | Smooth, dome-shaped, translucent; absolute field defect; normal choroidal vessels visible; no SRF shift |
| Choroidal detachment | Brown, smooth, immobile; extends anterior to ora serrata; limited posteriorly by vortex veins |
| Exudative RD | No break; SRF shifts with gravity; smooth convex surface |
| Tractional RD | Concave surface; no free SRF; no primary break (proliferative membranes) |
Complications
Proliferative Vitreoretinopathy (PVR)
- Main cause of surgical failure
- Epiretinal and subretinal membrane formation → tangential traction → fixed star-fold retinal folds
- Graded A (vitreous cells), B (retinal wrinkling), C (fixed folds)
- Usually follows surgery for RRD or penetrating injury
Workup
- Slit-lamp examination — assess anterior vitreous (tobacco dust), lens status, PVD
- Indirect ophthalmoscopy with scleral depression — entire periphery of both eyes; locate all breaks
- B-scan ultrasonography — when media opacities prevent fundal view (dense VH, dense cataract)
- OCT — identifies tractional membranes; distinguishes tractional component; assesses macular status
Treatment
Urgency
- Macula-on RD → emergency surgery (same day / next day) — visual prognosis significantly better
- Macula-off RD → urgent but not emergency; outcomes do not worsen if repaired within 7–10 days
- Macula-off chronic RD → repair within 1 week if possible
- Urgent surgery also needed for: superior or large break, high myopia (rapid SRF spread), vitreous haemorrhage with B-scan-confirmed RD
- Pre-operatively: minimise activity, bed-rest with break in the most dependent position
Surgical Options
1. Pneumatic Retinopexy
- Outpatient procedure
- Intravitreal gas bubble (SF₆ or C₃F₈) + cryotherapy/laser to seal break
- Advantages: minimally invasive, quick, office-based
- Limitations: success rates lower than scleral buckling
- Indication: uncomplicated RD with small break or breaks <2 clock hours in the upper two-thirds of peripheral retina
2. Scleral Buckling (Conventional/External)
- Silicone explant sutured onto sclera → inward indentation closes break by opposing RPE to neurosensory retina + reduces vitreoretinal traction
- Explant configurations: radial, segmental, circumferential, or encircling (360° band)
- Technique: peritomy → localize breaks → cryotherapy → suture explant → check buckle-break relation; drain SRF if needed
- Always indicated for post-traumatic dialysis
3. Pars Plana Vitrectomy (PPV)
- Increasingly preferred; >80% of primary RD surgery in the USA uses PPV
- Indicated when:
- Breaks cannot be visualized (VH, dense media opacity, posterior capsule opacification)
- Breaks unlikely to be closed by buckle (giant tears, large posterior breaks, PVR)
- Endotamponade with gas (SF₆, C₃F₈) or silicone oil maintains retinal apposition
Prognosis
- Anatomical success rate >90% with modern surgery
- Visual outcome depends on macular status pre-operatively
- Macula-on: good visual prognosis
- Macula-off: visual recovery incomplete; better if repaired within 72 hours to 7–10 days
Follow-Up
Post-surgery review: 1 day → 1 week → 1 month → 2–3 months → every 6–12 months. All patients require examination of the fellow eye for predisposing lesions.
Sources: Kanski's Clinical Ophthalmology: A Systematic Approach, 10th Ed., pp. 695–702; The Wills Eye Manual, 8th Ed., pp. 764–771
Principles of sclera buckling surgery and complications
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I now have all the content needed. Let me compile the comprehensive answer from the textbook material already retrieved (block5, lines 174–290+).
The key content I extracted covers:
- Principles (lines 174–232): definition, purpose, explants, configurations, technique, SRF drainage, adjuncts
- Surgical failure (lines 233–273): causes of failure with illustrations
- Complications (lines 242–290+): full list
Principles of Scleral Buckling Surgery & Complications
Definition & Rationale
Scleral buckling (SB) — also called conventional or external retinal detachment surgery — is a procedure in which a material (explant) is sutured onto the outer scleral surface to create an inward indentation (buckle) of the globe wall.
Two fundamental aims:
- Close retinal breaks by apposing the RPE to the detached neurosensory retina, eliminating the pathway for liquefied vitreous to enter the subretinal space
- Reduce dynamic vitreoretinal traction at sites of local vitreoretinal adhesion — preventing reopening of breaks
Scleral buckling must always be used for retinal detachment secondary to post-traumatic dialysis — Kanski's Clinical Ophthalmology, p. 701
The Explant
- Made from soft or hard silicone (sponge or solid)
- The entire break should be surrounded by ~2 mm of buckle
- The buckle must also cover the vitreous base anterior to the tear — to prevent subsequent reopening and anterior SRF leakage
- Break dimensions are estimated by comparing with the optic disc diameter
Buckle Configurations
| Configuration | Use |
|---|---|
| Radial (perpendicular to limbus) | Single U-tear; prevents fish-mouthing; used with radial explant (plomb) |
| Segmental (circumferential segment) | Small cluster of breaks in one quadrant |
| Circumferential (broad arc) | Multiple breaks in one or two quadrants |
| Encircling (360° band) | Multiple breaks in ≥2 quadrants, PVR, aphakic/pseudophakic RD, undetected breaks |
Surgical Technique (Step-by-Step)
Step 1 — Anaesthesia
Peribulbar or general anaesthesia.
Step 2 — Peritomy (Conjunctival Incision)
360° or limited peritomy to expose the sclera and allow access to all four quadrants. The rectus muscles are identified and, if needed, slung with sutures for globe control.
Step 3 — Localization of Breaks
The break is localized with indirect ophthalmoscopy and the sclera is marked with a diathermy pen under BIO guidance. Accurate localization is the most critical step.
Step 4 — Cryotherapy (Retinopexy)
Applied around the retinal break under BIO visualization — ice ball visible through retina confirms adequate application. Creates a chorioretinal adhesion that seals the break after retinal reattachment.
Step 5 — Suturing the Explant
- Mattress sutures placed in partial-thickness sclera
- Explant of appropriate dimensions oriented correctly (radial/circumferential) and sutured to sclera
- Position checked to confirm the buckle is correctly placed relative to the break
Step 6 — Drainage of Subretinal Fluid (SRF)
Optional but important decision:
| Drain SRF | Do Not Drain SRF |
|---|---|
| Very high IOP after buckle | Fresh, mobile RD |
| Longstanding RD with thick SRF | Young patient with mobile SRF |
| Inferior RD | Low operative risk acceptable |
| Suspected subretinal membranes |
Drainage technique: A sclerotomy is made over the area of deepest SRF; the choroid is perforated carefully. Risks include: choroidal haemorrhage, retinal incarceration, subretinal haemorrhage, and inadvertent perforation of the retina.
Step 7 — Intraocular Pressure Management
After drainage or a tight buckle, IOP may rise. Options:
- Anterior chamber paracentesis
- Intravitreal gas injection (also aids break closure)
Step 8 — Final Check
BIO used to confirm: (a) break is on the buckle, (b) retinal vascularity is preserved (patent central retinal artery), (c) IOP not critically raised.
Step 9 — Wound Closure
Conjunctiva re-approximated with absorbable sutures. Subconjunctival antibiotic and steroid injected.
Adjunctive Procedures
- Laser photocoagulation (photocoagulation retinopexy): Post-operatively when retina is flat; creates permanent chorioretinal adhesion
- Intravitreal gas (SF₆ or C₃F₈): Adjunct tamponade; patient positioned to keep gas against break
- Encircling band: Used when breaks are multiple, in multiple quadrants, or when PVR is present — reduces vitreoretinal traction globally
Causes of Surgical Failure
The common causes of failure (retina remains detached or re-detaches) are:
| Cause | Explanation |
|---|---|
| Break not on the buckle | Incorrect localization or buckle displacement |
| Undersized explant | Break extends beyond margins of buckle |
| New / missed breaks | Secondary breaks not identified pre-op |
| Fish-mouthing of U-tear | Radial folds at the edges of a U-tear keep it open — requires radial explant or gas tamponade |
| PVR | Epiretinal/subretinal membranes contract → fixed star-folds → re-detachment |
| Buckle slippage or extrusion | Explant migrates or erodes through conjunctiva |
Complications of Scleral Buckling
Intraoperative
| Complication | Notes |
|---|---|
| Choroidal haemorrhage | During SRF drainage; ranges from minor to expulsive |
| Retinal perforation | Needle or drainage site penetrates retina |
| Subretinal haemorrhage | From drainage; may spread under retina |
| Retinal incarceration | Retina drawn into drainage site |
| Vitreous loss | May occur if globe perforated |
Early Postoperative
| Complication | Notes |
|---|---|
| Raised IOP | From tight buckle, forward rotation of lens-iris diaphragm, or choroidal detachment; may require paracentesis |
| Choroidal detachment | From hypotony post-drainage; usually resolves spontaneously |
| Anterior segment ischaemia | From ischaemia of the anterior segment if >2 rectus muscles are disinserted; presents with corneal oedema, cells, flare, dilated episcleral vessels |
| Ocular motility disturbance / diplopia | Muscle scarring or displacement |
| Conjunctival wound dehiscence | Especially with 360° peritomy |
Late Postoperative
| Complication | Notes |
|---|---|
| Buckle extrusion / exposure | Explant erodes through conjunctiva; risk increased by infection, thin conjunctiva |
| Buckle infection | Requires explant removal in most cases |
| Induced refractive change | Encircling band increases axial length → myopic shift; may cause anisometropia |
| Strabismus / diplopia | Extraocular muscle restriction by explant; common with large or encircling buckles |
| Cataract | More common with encircling procedures + drainage |
| Epiretinal membrane (macular pucker) | Proliferative response on retinal surface post-repair |
| PVR (proliferative vitreoretinopathy) | Main late cause of failure; epiretinal membranes → star folds → re-detachment |
| Fish-mouthing | Radial folds at U-tear edges preventing closure |
| Macular pucker | Epiretinal membrane causing metamorphopsia |
| Retinal re-detachment | From new/missed breaks, PVR, or buckle failure |
| Subretinal fluid persistence | Chronic SRF may persist for months even with anatomical success |
Outcomes
- Anatomical success rate: ~85–90% with a single procedure
- Visual outcome depends on pre-operative macular status
- Encircling buckles carry a higher rate of myopic shift and motility disturbance than segmental buckles
- Success rate is lower if PVR is present pre-operatively
Source: Kanski's Clinical Ophthalmology: A Systematic Approach, 10th Ed., pp. 700–704
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