Optic Pit with Serous Macular Detachment MCQ — NEET PG Practice Question | NEETPGAI
Optic Pit with Serous Macular Detachment
medium
eye Ophthalmology
A 42-year-old man presents with progressive metamorphopsia and blurred central vision for 6 months. Fundoscopy reveals a small grayish-white excavation at the inferotemporal margin of the optic disc with shallow macular elevation. OCT shows a two-layer schisis pattern with outer-layer break communicating with the pit. The structure marked **B** in the diagram is responsible for this presentation. Which of the following best describes the embryological origin and pathophysiology of this condition?
A. Abnormal development of the peripapillary retinal pigment epithelium leading to focal choriocapillaris atrophy
B. Incomplete fusion of the superior and inferior optic nerve sheaths with subsequent fluid accumulation in the nerve fiber layer
C. Complete agenesis of the optic nerve head with secondary retinal folding and choroidal neovascularization
D. Incomplete closure of the embryonic fetal fissure with herniation of dysplastic retinal tissue into a collagen-lined defect communicating with the subarachnoid space and vitreous cavity
Explanation
Why option 1 is right
The structure marked B (optic pit with serous macular detachment) is a congenital cavitary anomaly of the optic nerve head resulting from incomplete closure of the embryonic fetal fissure. The pit represents a collagen-lined defect that communicates with both the subarachnoid space and the vitreous cavity, allowing dysplastic retinal tissue to herniate into this space. This communication permits fluid (from vitreous, cerebrospinal fluid, or choroidal sources) to enter the subretinal space, causing the characteristic two-layer schisis pattern with serous macular detachment seen on OCT. This pathophysiology directly explains the patient's presentation of metamorphopsia, micropsia, and progressive vision loss in the third to fourth decade of life (AAO BCSC Section 12: Retina).
Why each distractor is wrong
Option 2: Complete agenesis of the optic nerve head is a severe developmental anomaly incompatible with the patient's preserved optic disc architecture and the characteristic small excavation visible on fundoscopy. Optic pit is a partial defect, not complete agenesis.
Option 3: Abnormal RPE development and choriocapillaris atrophy would present as geographic atrophy or choroidal hypoperfusion, not as a discrete cavitary defect at the disc margin with a two-layer schisis pattern on OCT.
Option 4: Incomplete fusion of optic nerve sheaths is not the embryological basis of optic pit; this would not explain the communication with the subarachnoid space or the herniation of dysplastic retinal tissue into a collagen-lined cavity.
High-YieldNEET PG
Optic pit is an incomplete closure of the embryonic fetal fissure (not complete agenesis) with a collagen-lined cavity communicating with both subarachnoid space and vitreous—this dual communication explains fluid entry and maculopathy in 25–75% of cases by the 3rd–4th decade.
