Best Vitelliform Macular Dystrophy.

Autosomal recessive bestrophinopathy (ARB) results from a total absence of functional bestrophin-1 protein owing to two BEST1 mutations, one on each of the chromosomes. If present at an early age, the presenting feature could be decreased vision due to amblyopia. Refractive error is hyperopia, predisposing these eyes for acute angle-closure glaucoma. The yellowish lesions are larger and more extensive-extending beyond the arcades-than in the typical autosomal dominant Best disease. Some of the eyes also show numerous yellowish subretinal dots. Lesions are multifocal (Fig. 29.1). Subretinal fibrosis in the macular area is a common feature. Optical coherence tomography (OCT) may show cystoid changes in the neurosensory retina. Fundus autofluorescence (FAF): Increased AF reflects lipofuscin accumulation in the RPE; decreased AF reflects RPE atrophy. Electroretinography (ERG): As panretinal photoreceptor dysfunction progresses with advancing age, full-field (FF) ERG shows delayed rod and cone responses. Electrooculography (EOG): Abnormal Arden ratio.

Underdeveloped RPE Apical Domain Underlies Lesion Formation in Canine Bestrophinopathies.

Canine bestrophinopathy (cBest) is an important translational model for BEST1-associated maculopathies in man that recapitulates the broad spectrum of clinical and molecular disease aspects observed in patients. Both human and canine bestrophinopathies are characterized by focal to multifocal separations of the retina from the RPE. The lesions can be macular or extramacular, and the specific pathomechanism leading to formation of these lesions remains unclear. We used the naturally occurring canine BEST1 model to examine factors that underlie formation of vitelliform lesions and addressed the susceptibility of the macula to its primary detachment in BEST1-linked maculopathies.