Serous (Exudative) Retinal Detachment

Definition

Pathogenesis

1. Vascular, inflammatory, or neoplastic disease involving the retina, RPE, or choroid causes fluid to leak outside vessels.
2. The subretinal space accumulates protein-rich fluid.
3. There is no retinal break — fluid is purely exudative/transudative in origin.

Key TIP: An exudative RD (often caused by a choroidal tumour) is characterized by 'shifting' subretinal fluid — Kanski's Clinical Ophthalmology

Causes (Etiology)

Rule of thumb: An intraocular tumour should be considered the cause of exudative RD until proved otherwise.

Symptoms

• Visual field defect with varying degrees of vision loss
• Visual changes may vary with changes in head position (pathognomonic)
• Photopsia is typically absent (no vitreoretinal traction)
• Floaters may be present if associated vitritis exists
• Bilateral involvement possible depending on cause (e.g., VKH, toxaemia of pregnancy)

Signs

Fig. Exudative retinal detachment caused by a choroidal melanoma — smooth bullous detachment with SRF (Kanski's Clinical Ophthalmology)

• Serous elevation of the retina with shifting SRF on positional change
  • Sitting upright → SRF accumulates inferiorly, detaching inferior retina
  • Supine position → SRF shifts posteriorly, detaching the macula
• No retinal break identified
• Detachment typically does not extend to the ora serrata
• Retina surface is smooth (not corrugated as in rhegmatogenous RD) and may become bullous
• The detached retina is highly mobile
• Mild relative afferent pupillary defect (RAPD) may be present in large detachments
• 'Leopard spots' — scattered subretinal pigment clumping — may appear after the detachment resolves
• The underlying cause (e.g., choroidal tumour) may be visible on fundoscopy or B-scan

Differentiating Exudative from Other Types of RD

Investigations (Workup)

1. Fundoscopy — assess character of detachment, identify underlying lesion
2. Intravenous Fluorescein Angiography (IVFA) — demonstrates leakage or pooling and identifies the SRF source
3. OCT (Optical Coherence Tomography) — identifies the source of SRF (e.g., CNV); shows smooth subretinal fluid dome
4. B-scan Ultrasonography — helps delineate the underlying cause (tumour, posterior scleritis); shows mobile retina
5. Systemic workup — to rule out inflammatory, neoplastic, or vascular causes (BP, autoimmune screen, chest X-ray, oncology)
6. Fundus Autofluorescence (FAF) — demonstrates hyperautofluorescence in areas of serous detachment

Treatment

• Neoplastic causes — treat the primary tumour (photocoagulation, PDT, radiotherapy, enucleation for melanoma)
• Inflammatory causes (VKH, posterior scleritis) — systemic corticosteroids
• CSCR with bullous detachment — the leaking RPE site may be sealed by laser photocoagulation or PDT
• Choroidal haemangioma — PDT; laser photocoagulation (low success rate)
• Some cases resolve spontaneously after treatment of the underlying cause
• Anti-VEGF injections for CNV-driven exudative detachment

Complications (if untreated)

• Chronic macular damage with permanent visual loss
• 'Leopard spot' RPE atrophy after resolution
• Choroidal neovascularization as a secondary complication
• Phthisis bulbi (end-stage)

Diagnosis and Management of Serous (Exudative) Retinal Detachment

A. DIAGNOSIS

1. Clinical Diagnosis

History

• Painless visual field defect with variable vision loss
• Visual changes that shift with head position — the hallmark of exudative RD
• No flashing lights (photopsia) — absence distinguishes it from rhegmatogenous RD
• Possible bilateral involvement (VKH, toxaemia of pregnancy)
• History of systemic disease: hypertension, malignancy, autoimmune disease, steroid use

Fundoscopic Findings (Ophthalmoscopy)

• Smooth, bullous, convex elevation of the detached retina (not corrugated)
• Shifting subretinal fluid (SRF) — classic and pathognomonic
  • Sitting: SRF collects inferiorly → inferior retinal detachment
  • Supine: SRF shifts to posterior pole → macular detachment
• No retinal break identifiable
• Does not extend to the ora serrata
• Highly mobile retina
• Underlying lesion (tumour, haemangioma) may be visible
• 'Leopard spots' — scattered subretinal pigment clumping after resolution

2. Investigations

A. Optical Coherence Tomography (OCT)

• First-line investigation
• Shows optically empty subretinal space (neurosensory elevation)
• Identifies RPE detachments, precipitates on posterior retinal surface
• Quantifies SRF height — correlates with disease activity (especially in VKH)
• Detects subretinal septae (VKH), CNV membranes, RPE tears
• Thickened choroid seen in CSCR (pachychoroid)

B. Fundus Fluorescein Angiography (FFA/IVFA)

• Demonstrates leakage or pooling from the SRF source
• Choroidal tumour: irregular hyperfluorescence with late staining
• CSCR (Central Serous Chorioretinopathy):
  • Early: hyperfluorescent spot at RPE leak site
  • Expands as an "ink-blot" (most common) or "smokestack" pattern (less common)
  • Late: pooling of dye within the detachment

Fig. FA of CSCR — (A,B) 'Ink-blot' appearance; (C,D) 'Smokestack' appearance (Kanski's Clinical Ophthalmology)

• VKH: Multifocal hyperfluorescent dots at RPE level → subretinal pooling in acute phase; RPE window defects in chronic phase
• Posterior scleritis: Associated disc swelling, choroidal folds

C. B-Scan Ultrasonography

• Identifies the underlying cause: choroidal tumour (elevated, acoustically solid), diffuse choroidal thickening (VKH, posterior scleritis)
• Demonstrates highly mobile retina on dynamic B-scan
• Excludes posterior scleritis (diffuse choroidal thickening + T-sign of posterior scleritis)
• Helpful when media opacities prevent fundal view

D. Fundus Autofluorescence (FAF)

• Hyperautofluorescence in areas of active serous detachment (VKH)
• Hypoautofluorescence at RPE leakage site and old lesion sites (CSCR)
• Gravitational tract (dependent SRF tracking) visible in chronic CSCR

E. Indocyanine Green Angiography (ICGA)

• In VKH: regularly distributed hypofluorescent spots in acute phase; diffuse posterior pole hyperfluorescence in late phase; useful for monitoring
• In CSCR: dilated choroidal vessels, choroidal hyperpermeability in mid-phase; identifies subclinical foci

F. Systemic Workup (to identify underlying cause)

• Blood pressure measurement (malignant hypertension)
• Urinalysis / obstetric review (pre-eclampsia/toxaemia)
• Oncology screen: chest X-ray, CT thorax/abdomen/pelvis, tumour markers (metastasis)
• Autoimmune screen: ANA, HLA-B27, ACE, chest X-ray (sarcoid, VKH)
• Lumbar puncture if VKH uncertain: CSF shows transient lymphocytic pleocytosis + melanin-containing macrophages

G. Amsler Grid

• Confirms metamorphopsia corresponding to the macular detachment (especially in CSCR)

B. MANAGEMENT

1. Inflammatory Causes

Vogt-Koyanagi-Harada (VKH) Syndrome

• High-dose oral prednisolone 1–2 mg/kg/day, tapered over 3–6 months
• May be preceded by IV methylprednisolone pulse (500–1000 mg/day for 3 days)
• Topical steroids + cycloplegics for anterior uveitis
• Steroid-resistant: immunosuppressives (azathioprine, mycophenolate)
• Biological agents (infliximab) if no response to steroids — use early

Posterior Scleritis

• NSAIDs or systemic corticosteroids
• Immunosuppressives for recurrent/chronic cases

2. Central Serous Chorioretinopathy (CSCR)

Key TIP: All corticosteroid treatment must be discontinued if possible in chronic or recurrent CSCR — Kanski's Clinical Ophthalmology

3. Neoplastic Causes

4. Vascular Causes

5. Idiopathic / Structural Causes

• Uveal effusion syndrome: sclerotomy / partial-thickness sclerectomy to improve transscleral fluid outflow
• Optic pit with serous detachment: vitrectomy + gas tamponade ± laser photocoagulation around the pit
• Bullous CSCR: PDT ± laser photocoagulation to seal RPE leak

Summary Algorithm

Exudative RD confirmed (smooth, shifting SRF, no break)
        ↓
Identify underlying cause (FFA, OCT, B-scan, systemic workup)
        ↓
┌────────────────┬──────────────────┬────────────────────┬──────────────┐
│  Inflammatory  │    Neoplastic    │     Vascular       │  Idiopathic  │
│ VKH / scleritis│ Melanoma/mets/   │ HTN/preeclampsia/  │  CSCR / UES  │
│ → Systemic     │  haemangioma     │ CNV/Coats          │ → Observe /  │
│   steroids /   │ → Tumour-        │ → Anti-VEGF /      │   stop       │
│   immuno-      │   specific Rx    │   BP control       │   steroids / │
│   suppressives │                  │                    │   PDT/laser  │
└────────────────┴──────────────────┴────────────────────┴──────────────┘