Question:medium
A young patient presents to the ophthalmology clinic with loss of central vision. There is no obvious family history. The electroretinogram (ERG) was observed to be normal. Which is the most probable diagnosis?
A young patient presents to the ophthalmology clinic with loss of central vision. There is no obvious family history. The electroretinogram (ERG) was observed to be normal. Which is the most probable diagnosis?
Show Hint
Macula-only disease leaves the full-field ERG normal; think of the commonest juvenile macular dystrophy.
Updated On: Jun 24, 2026
- Best's disease
- Stargardt's disease
- Retinitis pigmentosa
- Macular hole
Show Solution
The Correct Option is B
Solution and Explanation
Start from the single most discriminating data point: the ERG is normal. The full-field ERG sums signals from all rods and cones across the retina, so any disease that spreads over the whole retina (like retinitis pigmentosa) drags the ERG down. Because the ERG here is preserved, the lesion must be restricted to the macula, where the cell count is too small to move the whole-retina response.
Now narrow within the macular dystrophies. The patient is young, has central vision loss, and lacks an obvious family history. Stargardt's disease is the commonest juvenile macular dystrophy, is inherited in an autosomal recessive pattern (so it frequently looks sporadic), and famously leaves the early full-field ERG normal. Every clue lines up.
Rule out the distractors by their signature tests and inheritance: Best's disease is autosomal dominant and is detected by an abnormal EOG (reduced Arden ratio), not a normal ERG; retinitis pigmentosa abolishes the ERG; and a macular hole is a mechanical defect of older eyes, not a young dystrophy. Therefore the picture is classic for Stargardt's disease.
\[\boxed{\text{Stargardt's disease}}\]
Now narrow within the macular dystrophies. The patient is young, has central vision loss, and lacks an obvious family history. Stargardt's disease is the commonest juvenile macular dystrophy, is inherited in an autosomal recessive pattern (so it frequently looks sporadic), and famously leaves the early full-field ERG normal. Every clue lines up.
Rule out the distractors by their signature tests and inheritance: Best's disease is autosomal dominant and is detected by an abnormal EOG (reduced Arden ratio), not a normal ERG; retinitis pigmentosa abolishes the ERG; and a macular hole is a mechanical defect of older eyes, not a young dystrophy. Therefore the picture is classic for Stargardt's disease.
\[\boxed{\text{Stargardt's disease}}\]
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