Improvement of S-cone mediated visual fields and rod function after correction of vitamin A deficiency

Purpose: To evaluate visual sensitivities mediated via short wavelength sensitive (SWS) cones and retinal function electrophysiologically in a patient with vitamin A deficiency. Methods: This is an interventional case report. Ophthalmological examinations were performed. Full-field electroretinograms (ERGs) were recorded. Mean deviation (MD), a global index that reflects the overall depression in visual fields, was evaluated using Humphrey standard automated perimetry (SAP) and short wavelength automated perimetry (SWAP). Results: A 65-year-old Japanese female, who was diagnosed with primary sclerosing cholangitis, complained of night blindness. Her visual acuity was 1.2 in both eyes. The ERGs showed no rod b-waves, reduced rod-plus-cone responses (negative type) and normal cone and 30-Hz flicker responses. Plasma vitamin A concentration was 18 IU/dL (normal range 97-316 IU/dL). The SAP MD was -1.09 dB (OD) and -0.97 dB (OS), whereas the SWAP MD was -10.10 dB (OD) and -10.50 dB (OS). The rate of sensitivity decreased in increasing eccentricity in SWAP. The ERG responses were normalized 4 months after oral administration of vitamin A. The SWAP MD was greatly improved to -3.47 dB (OD) and -4.10 dB (OS) compared with the changes to the SAP MD (OD: +0.67 dB, OS: +0.41 dB). Conclusions: Rod dysfunction and impaired SWS cone mediated pathways were preferentially observed and were subsequently reversed after the treatment. The findings suggest that rods and SWS cones are more susceptible to vitamin A deficiency than long/middle wavelength sensitive cones in the patient.