Improvement in S-cone–mediated Visual Fields and Rod Function after Correction of Vitamin a Deficiency

Abstract

To evaluate S-cone-mediated visual fields and full-field electroretinograms (ERGs) in a patient with vitamin A deficiency. A 65-year-old woman diagnosed with primary sclerosing cholangitis reported experiencing night blindness. The patient underwent comprehensive ophthalmic examination, including funduscopy, ERGs, Humphrey standard automated perimetry (SAP), and short-wavelength automated perimetry (SWAP). Serum vitamin A concentrations were measured. The patient's best-corrected visual acuity was 1.2 in both eyes. The ERG results showed no rod b-waves, reduced combined rod-plus-cone responses (negative type), and normal cone and 30-Hz flicker responses. Serum vitamin A concentration was 18 IU/dL (normal range 97-316 IU/dL). The SAP mean deviation (MD) values were -1.09 dB (OD) and -0.97 dB (OS), whereas the SWAP MD values were -10.10 dB (OD) and -10.50 dB (OS). The rate of sensitivity decreased with increasing eccentricity in SWAP. Four months after starting oral administration of vitamin A, all ERG values were normalized, and SWAP MD values were greatly improved (OD -3.47 dB, OS -4.10 dB) compared with changes in SAP MD values (OD +0.67 dB, OS +0.41 dB). Rod dysfunction and impaired S-cone-mediated pathways were preferentially observed and found to be reversed after the treatment. The findings in this patient suggest that rods and S cones are more susceptible to vitamin A deficiency than L and M cones. Vitamin A deficiency visual impairment may therefore be reversible with appropriate therapy.