## Analysis of Retinal Detachment Pathophysiology ### Understanding the Correct Answer **Key Point:** Posterior vitreous detachment (PVD) is **NOT** a necessary prerequisite for rhegmatogenous retinal detachment (RRD). While PVD is the most common precipitating event (~70% of RRDs), retinal breaks can occur without PVD — for example, in young myopes with lattice degeneration, atrophic holes, or traumatic dialyses. Therefore, Option C is **FALSE** and is the correct "EXCEPT" answer. ### Why the Other Options Are TRUE (and thus not the answer) | Option | Statement | Verdict | |--------|-----------|---------| | **A** | Vitreous traction is the primary mechanism in **tractional** RD | ✅ TRUE — tractional RD (e.g., in proliferative diabetic retinopathy) is driven by fibrovascular membrane traction, distinct from rhegmatogenous RD | | **B** | Myopia is a risk factor due to increased axial length and vitreous liquefaction | ✅ TRUE — high myopia (>6 D) carries 5–10× higher RD risk due to axial elongation, lattice degeneration, and early vitreous syneresis | | **D** | Macula is spared in superior detachments if the break is above the equator | ✅ TRUE (as a general clinical observation) — in superior breaks, gravity causes fluid to track inferiorly, away from the macula initially; this is why superior detachments tend to be slower to involve the macula compared to inferior breaks | ### Pathophysiology of Rhegmatogenous RD 1. A **full-thickness retinal break** (tear, hole, or dialysis) forms — this is the defining feature 2. **Liquefied vitreous** passes through the break into the subretinal space 3. Progressive separation of the neurosensory retina from the RPE follows 4. PVD commonly precedes horseshoe tears (dynamic traction), but **atrophic round holes** and **dialyses** can cause RRD without PVD **Clinical Pearl:** The three types of retinal breaks are: - **Horseshoe (flap) tears** — most common, caused by dynamic vitreous traction during PVD - **Atrophic round holes** — occur in lattice degeneration, often WITHOUT PVD - **Dialyses** — peripheral retinal separations, often traumatic, WITHOUT PVD **High-Yield:** PVD is the most common *precipitating* event for RRD but is NOT a *necessary prerequisite*. This distinction is frequently tested in NEET PG / INI-CET. ### Macular Status and Urgency - **Macula-on RD:** Surgery within 24–48 hours to preserve central vision - **Macula-off RD:** Surgery within 48–72 hours; visual prognosis is guarded [cite: Parson's Diseases of the Eye 22e Ch 11; Kanski's Clinical Ophthalmology 9e Ch 14]
Sign up free to access AI-powered MCQ practice with detailed explanations and adaptive learning.