Question:easy
A patient came with nyctalopia. Fundus image given below, what will be the diagnosis?
A patient came with nyctalopia. Fundus image given below, what will be the diagnosis?
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Night blindness plus bony-spicule pigment, thin vessels and a waxy disc on fundus = a hereditary rod-cone dystrophy.
Updated On: Jun 22, 2026
- Retinitis pigmentosa
- Vit A deficiency
- Retinal detachment
- Diabetic retinopathy
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The Correct Option is A
Solution and Explanation
Approach by mechanism of night blindness. Night vision depends on functioning rod cells. When rods fail, the patient cannot see in dim light (nyctalopia). The two commonest causes are an inherited rod degeneration (retinitis pigmentosa) and lack of vitamin A, which is the substrate for rhodopsin. The fundus photograph is the decider.
What the fundus tells us. Retinitis pigmentosa produces a pathognomonic picture: dark bony-spicule pigment clumps scattered in the mid-periphery, markedly narrowed (attenuated) retinal vessels, and a waxy, pale optic disc. This image shows exactly that pattern.
Why the answer is retinitis pigmentosa. It is a progressive hereditary rod-cone dystrophy in which rods die first; this explains the early lifelong night blindness and the ring/tunnel-vision field defect, and the degenerating retinal pigment epithelium deposits the characteristic spicular pigment.
Ruling out the other choices. Vitamin A deficiency gives nyctalopia but with xerophthalmia signs (Bitot spots, conjunctival/corneal xerosis), not retinal spicules. A detachment looks like a raised grey retinal fold with acute curtain-like loss. Diabetic retinopathy shows haemorrhages, exudates and new vessels with gradual visual blurring, not pure night blindness.
Hence the diagnosis is Retinitis pigmentosa (Option A).
What the fundus tells us. Retinitis pigmentosa produces a pathognomonic picture: dark bony-spicule pigment clumps scattered in the mid-periphery, markedly narrowed (attenuated) retinal vessels, and a waxy, pale optic disc. This image shows exactly that pattern.
Why the answer is retinitis pigmentosa. It is a progressive hereditary rod-cone dystrophy in which rods die first; this explains the early lifelong night blindness and the ring/tunnel-vision field defect, and the degenerating retinal pigment epithelium deposits the characteristic spicular pigment.
Ruling out the other choices. Vitamin A deficiency gives nyctalopia but with xerophthalmia signs (Bitot spots, conjunctival/corneal xerosis), not retinal spicules. A detachment looks like a raised grey retinal fold with acute curtain-like loss. Diabetic retinopathy shows haemorrhages, exudates and new vessels with gradual visual blurring, not pure night blindness.
Hence the diagnosis is Retinitis pigmentosa (Option A).
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