A 72-year-old woman from Delhi with a history of cataract surgery 3 years ago presents with gradual onset of floaters and a shadow in the inferior nasal field of her left eye over 1 week. She denies photopsia. Visual acuity is 6/18 in the left eye. On fundoscopy, a shallow retinal detachment is seen in the inferior nasal quadrant with a smooth, convex border and no visible retinal breaks. B-scan ultrasonography shows a thin, mobile membrane. What is the most likely diagnosis?

Explanation

## Clinical Scenario Analysis This is a **post-cataract surgery patient** presenting with gradual onset floaters, inferior nasal field shadow, **no photopsia**, a **shallow retinal detachment with smooth, convex border**, **no visible retinal breaks**, and a **thin, mobile membrane on B-scan**. These features are classic for **exudative (serous) retinal detachment**, most likely from **choroidal neovascularization (CNV)**. ### Why Exudative Retinal Detachment? **Key Point:** Exudative retinal detachment is characterized by: - **Smooth, convex (dome-shaped) detachment border** — fluid shifts with gravity (shifting fluid sign) - **Absence of retinal breaks** — no tear or hole - **Absence of photopsia** — no vitreoretinal traction - **Thin, mobile membrane on B-scan** — fluid-filled subretinal space, not fixed fibrous tissue - **Gradual onset** — consistent with progressive subretinal fluid accumulation **High-Yield:** The **shifting fluid sign** (subretinal fluid moves with patient position) is pathognomonic of exudative detachment and distinguishes it from tractional or rhegmatogenous types. ### Comparison of Retinal Detachment Types | Feature | Rhegmatogenous | Tractional (PVR) | Exudative | |---------|---|---|---| | **Onset** | Sudden | Gradual | Gradual | | **Photopsia** | Yes (early) | No | No | | **Retinal breaks** | Present | Absent | Absent | | **Detachment border** | Convex, mobile | **Concave, fixed** | **Convex, smooth** | | **B-scan** | Tall, mobile folds | Thin, **fixed** membrane | Thin, **mobile** membrane | | **Shifting fluid** | No | No | **Yes** | | **Risk factors** | Myopia, lattice | Prior surgery, trauma | Inflammation, choroidal disease, AMD | ### Why PVR (Option A) is Incorrect **Clinical Pearl:** PVR (proliferative vitreoretinopathy) produces a **tractional** detachment with: - **Concave, fixed border** (not convex) — due to membrane contraction pulling retina inward - **Fixed, immobile membrane on B-scan** (not mobile) — fibroglial tissue is rigid - Typically associated with prior rhegmatogenous detachment repair, not isolated cataract surgery The stem explicitly states **smooth, convex border** and **thin, mobile membrane** — both of which contradict PVR/tractional detachment morphology. These are hallmark features of **exudative** detachment. ### Pathophysiology of Exudative Detachment from CNV ``` Choroidal neovascularization (CNV) ↓ Abnormal new vessels breach Bruch's membrane ↓ Leakage of fluid/blood into subretinal space ↓ Accumulation of subretinal fluid ↓ Exudative (serous) retinal detachment ↓ Smooth, convex, mobile detachment — no breaks ``` ### Why Not the Other Options? | Option | Why Incorrect | |--------|---------------| | **PVR (A)** | PVR causes **concave, fixed** detachment with **immobile** membrane — opposite of what is described | | **Tractional from PDR (B)** | Requires diabetic history, neovascularization, vitreous hemorrhage; none present here | | **PCO (C)** | Posterior capsular opacification causes visual blur/glare, NOT retinal detachment; B-scan would not show a mobile membrane | ### Management of Exudative Detachment from CNV 1. **Identify underlying cause:** OCT, fluorescein angiography, ICGA 2. **Anti-VEGF therapy** (bevacizumab, ranibizumab, aflibercept) — first-line for CNV-related exudative detachment 3. **Photodynamic therapy** — for select subtypes (e.g., polypoidal choroidal vasculopathy) 4. **Treat systemic cause** if inflammatory etiology identified [cite: Kanski & Bowling Clinical Ophthalmology 9e Ch 12; Ryan's Retina 6e Ch 66; Yanoff & Duker Ophthalmology 5e]