Missense mutations of SLC38A8 can cause defects in the sixth transmembrane domain of photoreceptors, resulting in the underdevelopment of the retina. SLC38A8 codes for a glutamine transporter mainly expressed in the photoreceptor layer of the retina. SLC38A8 variants are responsible for an autosomal recessive form of foveal hypoplasia. PAX6 variants can cause autosomal dominant foveal hypoplasia and affect embryonic eye development, resulting in a range of phenotypes, the most common being aniridia. Multiple gene mutations have been linked to ocular albinism, with and without cutaneous involvement. Foveal hypoplasia is also associated withĪ multicenter observational study of 907 patients found that the most common genetic etiology for typical foveal hypoplasia was albinism (67.5%), followed by PAX6 (21.8%), SLC38A8 (6.8%), and FRMD7 (3.5%) gene variants.Prior studies have shown a small FAZ in patients with a history of prematurity. Prematurity is a significant risk factor due to the associated abnormal development of retinal vasculature and deficiency of macular pigmentation in these patients.It is hypothesized that fetal endothelial cell and macular pigmentary development are key to the proper development of the foveal pit. There are numerous risk factors associated with foveal hypoplasia including those that are developmental and genetic in nature. However, many studies show the frequency of foveal hypoplasia occurrence in associated diseases. Because foveal hypoplasia is commonly associated with a number of ocular diseases, there does not seem to be a widely accepted standalone statistic on its prevalence or incidence in isolation. EpidemiologyĪ cross-sectional study by Noval et al with 286 healthy children found that up to 3% of children had an anatomically underdeveloped foveal pit ( fovea plana) bilaterally on OCT ( optical coherence tomography). Later use of imaging techniques such as fundus fluorescein angiography to identify absent foveal avascular zones (FAZ) have found cases of isolated foveal hypoplasia without associated nystagmus or comorbidities. Other conditions were later discovered to be associated with foveal hypoplasia, including macular aplasia, macular coloboma, and albinism. HistoryĮarly descriptions of foveal hypoplasia in the early 1900s were in association with other diseases, particularly hereditary nystagmus while assessing for retinal abnormalities with ophthalmoscopy. This, in the most basic sense, allows for the central area of the eye and brain to increase the sampling rate of each photon that enters the retina. Īlthough the foveal pit does not fully develop in foveal hypoplasia, there is developmental plasticity in the retina that allows cone cells in the foveal area to change their own shape to allow for a higher cone cell density in the fovea. Risk factors that affect foveal development, such as prematurity, can lead to foveal hypoplasia.
It may present in isolation or be associated with other conditions such as albinism, coloboma, optic nerve hypoplasia, retinopathy of prematurity, and aniridia. Other congenital anomalies of posterior segment of eye Q14.8įoveal hypoplasia is an ocular abnormality in which the foveal pit either fails to develop, or does not completely develop, and is associated with poor visual acuity and nystagmus. Other congenital anomalies of posterior segment 743.59
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