Young patient with macular dystrophy : Why Antioxidants and Vitamin A Aren’t Always the Answer

Fundus photograph

This was one of the very interesting case : A 18 year old boy came with c/o bilateral gradual painless diminution of vision . BCVA OU : 20/63

He was using his old glasses and there was no change in refraction, after slit lamp examination with 90D I observed loss of foveal reflex and there was this typical darker patch around the fovea.

Which was quite characteristic of para foveal pisciform flecks and there were sign of foveal thinning and atrophy too.

OD OCT macula

OS OCT macula

On OCT of both eye we came to know there were significant foveal thinning with loss of IS-OS zone (Photoreceptor zone).

By this time it was clear that young male with gradual dov in both eye and photorecptor layer loss suggestive of some macular dystrophy and as there were classical fleck sign around macula suggested it to be : Stargardt disease

FAF of both eye (beaten bronze appearance)

We performed FAF for this patient and this is the beaten bronze appearance sing..

Pathology : There is defect in ABCA4 gene which is associated with trans cellular transportation of molecule. Usually in normal cells when there is oxidative stress there will be production of lipofusin (Bisretinoid + Fluorophorus) while in photoreceptor cells it will be produce normally and transported to RPE Cells via phagocytosis.

while in stargadts this process will be disrupted and due to that products of visual cycle.

In detail it fail to transport N-retinylidene-PE across disc membranes, leading to progressive entrapment of this molecule inside the discs. N-retinylidene-PE reacts with available all-trans-retinal to form an intermediate byproduct, Di-retinoid-pyridinium-phosphatidylethanolamine (A2PE). Upon photoreceptor renewal, byproduct-loaded outer segments are taken up by the adjacent RPE. There, A2PE is converted to Di-retinoid-pyridinium-ethanolamine (A2E), a vitamin A dimer, which becomes permanently trapped in the RPE due to the impossibility of further hydrolyzation. A2E is a major component of lipofuscin, a hallmark of cellular degeneration.

So as such there are no proven treatment for this disease. as there is high role of Vitamin A in progression of visual cycle it will worsen the condition.

As general ophthalmologist this the common mistake by prescribing anti-oxidant to this patient as this will worsen the condition.