Spark ImageWise 26 – Retina

Solar Retinopathy

Dr. Swati Mishra, Dr. Sarang Lambat, Dr. Prabhat Nangia, Dr. Vinay Nangia 
Suraj Eye Institute, 559 New Colony, Nagpur 

Case Description
A male, 17 years of age, presented to SEI for a follow up. He had a history of eclipse burn 12 years ago. He did not have complaints of, blurred vision, central scotoma or metamorphopsia. On examination the visual acuity was 6/6, N6 in BE with a correction of -1.25 DS with +1.50 DC in BE. The anterior segment was within normal limits. Intra-ocular pressure (IOP) measured with Goldman applanation tonometer was 14 mm.Hg. in both eyes. 

Discussion

The retina is susceptible to at least 3 different forms of light damage—thermal, mechanical, and photochemical. The type of retinal damage depends on wavelength, energy level, duration of exposure, and degree of pigmentation.

Solar retinopathy refers to a photochemical toxicity and resultant injury to retinal tissues, usually occurring at the fovea, because the subject may be looking at the sun directly thereby focusing the rays on the fovea.  This entity is commonly associated with sun gazing or eclipse viewing, and often results in mild-to-moderate visual acuity deficit and/or central or para-central scotoma. A degree of recovery may occur spontaneously and occurs over the course of 3-6 months after the inciting event. Visual recovery may be incomplete, with a reduction of the degree of scotoma. A patient may suffer from permanent visual acuity deficit and central or para-central scotoma.

Our patient presented on the same day after watching a solar eclipse with both eyes at the age of 5 years.  He complained of sudden loss of vision in both eyes. We took the decision of injecting intravitreal Avastin, on the rationale that it may help in  reducing  the   heat induced retinal oedema caused by the eclipse burn.   Over a period of time his visual acuity recovered.  While his OCT shows the presence of ellipsoid zone loss in the fovea, he has no visual complaints. 

It is interesting to note that thermal damage did not affect the inner layers of the fovea. One may assume that the retinal pigment epithelium may act as a heat sink, causing thermal damage to the photoreceptors.  In this patient, surprisingly there is no pigment disturbance that is visible clinically or in the colour photographs, except for the presence of a yellow spot  at the fovea due to lipofuscin ( which is known to aggregate in diseased RPE cells)   in the exact area of the foveal burn and photoreceptor loss.  Further, while a punched out break is seen in the ellipsoid layer and the inter-digitation layer, there is no other  evidence of retinal pigment epithelial damage clinically and on  the OCT. It is of course possible, that the initial damage to the RPE has recovered naturally to an extent, while damage to the photoreceptors may not recover following thermal injury. It is also of relevance to note that the patient has 6/6 vision in both eyes. Presumably he must have some difficulty in seeing the smaller lines on the snellens vision chart but has learnt to navigate the possible small scotoma that may exist in view of the break in the photoreceptor layers. The OCT and associated vision also tells us that the apparently healthy and intact parafoveal photoreceptors may play a sufficiently important role in vision, even enabling 6/6 vision as in this patient. 

ReadWise

1. Michaelides M, Rajendram R, Marshall J, Keightley S. Eclipse retinopathy. Eye (Lond). 2001 Apr;15(Pt 2):148-51. doi: 10.1038/eye.2001.49. 
2. Youssef PN, Sheibani N, Albert DM. Retinal light toxicity. Eye (Lond). 2011;25(1):1-14. doi:10.1038/eye.2010.149
3. Hope-Ross MW, Mahon GJ, Gardiner TA, Archer DB. Ultrastructural findings in solar retinopathy. Eye (Lond). 1993;7 ( Pt 1):29-33. doi: 10.1038/eye.1993.7.

Dr. Sarang Lambat
MS, FRF
Consultant
Vitreoretinal services
Suraj Eye Institute
Nagpur
Email – education@surajeye.org