Fundus albipunctatus (FA) is a very distinct hereditary chorioretinal dystrophy. It is a type of congenital stationary night blindness with an autosomal recessive inheritance pattern. Fundus albipunctatus is characterized by small and discrete dots that are regular and monotonous in their uniformity throughout the fundus from the paramacular region to the equator, both rods and cones are equally affected. Delayed dark adaptation can be demonstrated with delays in recovery of rod and cone function. There is no affective treatment available to restore full receptor cell function. However, a high oral dose of beta-carotene may lead to an improvement in night blindness.
Mutations in the PRPH2 and RDH5 genes have been identified in patients with fundus albipunctatus. Mutations in the PRPH2 gene are the cause of the autosomal dominant form, while mutations in the RDH5 gene result in an autosomal recessive pattern. Also, mutations in the RLBP1 gene have been found in some affected families.
Humbert et al. (2006) studied a 24-year-old Moroccan patient with typical fundus albipunctatus, born of first-cousin parents. He carried a 7.36-kb homozygous deletion encompassing the last 3 exons of RLBP1 (7, 8, and 9) and part of the intergenic region between RLBP1 and ABHD2, which lies downstream of RLBP1.
Dessalces et al. (2013) performed clinical and molecular investigations in patients with retinitis punctata albescens (RPA) at various ages, from November 2003, through June 2012, with no planned patient follow-up. The study included 11 patients with RPA (mean age, 24 [range, 3-39] years) from seven families and 11 control subjects undergoing evaluation. All patients had night blindness (before age 6 years in 10). The dotlike deposits were generally dense but could be rare, appearing in adaptive optics as elongated structures with variable orientation and no foveal involvement. There was no specific refractive error, and visual acuity varied widely from normal (1.2) to counting fingers. Variable degrees of visual field impairment were present, and all patients had severely decreased electroretinographic responses with predominant rod impairment. Screening for mutations in the RLBP1 gene uncovered two novel mutations.
Katsanis et al. (2001) described four Saudi families affected with fundus albipunctatus. One of these families had two related nuclear families. The first patient had lifelong complaint of poor vision at the age of 3.5 years. He had also diffuse highly regular fine white dots in the post equatorial RPE, severely limited scotopic responses, and mildly reduced photopic responses with prolonged implicit times. His brother had lifelong history of difficulty with night- and dim light- vision at age of 10 years. He had moderately reduced scotopic responses and mild reduction of photopic voltages with slight prolongations of implicit times. Three other affected members manifested more advanced retinal pigmentary degeneration, modest retinal vascular attenuation, waxy pallor of the optic disks, peripheral clumped pigmentary degeneration at the level of the RPE with minimal bone spicules in the retina, and geographic atrophy of the macular RPE.