Phenotype of maculopathy in primary hyperoxaluria type 1

Abstract

PurposeTo describe the structural and functional characteristics of oxalate retinopathy, an entity described in only 40 cases until now.MethodsFive patients with molecularly confirmed primary hyperoxaluria type 1 were subjected to multimodal retinal imaging (spectral‐domain optical coherence tomography, white light, and HRA multispectral imaging) and functional testing, including color vision testing, Goldmann perimetry, and ISCEV standard electrophysiological testing.ResultsOne patient with a c.[33dupC]; c.[731T > C] mutation showed bilateral perifoveal retinal pigment epithelium hyperplasia. The fundus in the four other patients, all of whom share an identical homozygous c.[33dupC] mutation, ranged from normal to bilateral widespread distribution of retinal crystals and confluent macular retinal pigment epithelium hyperplasia with subfoveal fibrosis. All patients who had developed end‐stage renal disease showed some sign of retinopathy, more severe with earlier onset.ConclusionsRetinopathy in primary hyperoxaluria type 1 shows considerable interindividual variation. No correlation between genotype and retinal phenotype was detected. A proposed clinical grading system of oxalate maculopathy derived from a literature review may help clinicians in estimating not only current visual function but also prognosis in this patient population that largely consists of preverbal infants.