Multicolor Imaging Highlights Xerophthalmic Fundus

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PRESENTATION
Vitamin A is necessary for the function of retina, by the formation of pigments in rod and cone photoreceptors in the phototransduction cycle. One of the early ocular signs of vitamin A deficiency is nyctalopia. In prolonged untreated cases, other ocular signs including conjunctival Bitot's spots, corneal ulcer, and keratomalacia develop. [1] We present a 30-year-old male who was admitted for evaluation by the rheumatologist due to oligoarthralgia. The patient had bariatric surgery for morbid obesity seven years earlier.
The rheumatologist consulted us for the patient's foreign body sensation and night blindness complaints during the last one year.
His ophthalmic examination revealed bestcorrected visual acuity of 20/20 in both eyes by Snellen E-chart. Intraocular pressure was 12 mmHg and Ishihara test scores were 14/14 in both eyes. In slit-lamp examination, there was a reduction in tear meniscus height (5 mm) with bilateral Bitot's spots at the limbal conjunctiva [ Figure 1]. There were small yellowish punctate lesions in the peripheral retina [ Figure 2A-B]. The optic nerve, macula, and vessels seemed normal [ Figure 2C-D]. Peripheral spectral-domain optical coherence tomography (SD-OCT) showed sparse subretinal drusenoid deposit (SDD)like lesions bilaterally [ Figure 2G]. Fundus autofluorescence revealed a faint mottled hyperand hypoautofluorescent pattern in the periphery of the retina [ Figure 2H]. In contrast to fundus autofluorescence, multicolor imaging of the peripheral retina detected a vast number of lesions much more visible than in the autofluorescence images [ Figure 2E-F] (Spectralis, software version 6.16.6.0; Heidelberg, Germany).
In multi-color images, when the images from the three different channels were separated to red, green, and blue, we found that the infra-red reflectance photos did not show the lesions, but the blue and green reflectance images highlighted the xerophthalmic lesions similar to the multi-color images [ Figure 3].
A full-field standard electroretinogram (Ronald Consult, Wiesbaden, Germany) detected a bilateral reduction in amplitude of rod response and also a smaller reduction in combined rod-cone, oscillatory potential, and cone This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.   responses [ Figure 4]. According to these findings, we suspected vitamin A deficiency. Serum level of vitamin A was 2 μg/dL (normal range: 30-80 μg/dL) and the diagnosis was confirmed.
The patient was treated with intramuscular vitamin A followed by daily administration of oral 50,000 IU of retinol palmitate. The patient did not come back for follow-ups, but upon enquiry, he reported that nyctalopia improved.

DISCUSSION
Nowadays, one of the most common causes of vitamin A deficiency is malabsorption after bariatric surgery, like in the case of the current patient. [2] Xerophthalmic fundus lesions as presented in this patient are the accumulation of disrupted photoreceptors' outer segments (especially rods) based on histopathological evaluation. [3] According  to previous reports of xerophthalmic fundus, the most common finding in OCT is the disruption of the outer retinal layers, especially the ellipsoid zone and SDD-like lesions in the peripheral retina. [3][4][5] Additionally, multicolor imaging was performed and we found that xerophthalmic retinal lesions were much more detectable by fundus multicolor imaging compared to the infrared