Purpose: Multiple, bilateral areas of congenital hypertrophy of the retinal pigment epithelium (CHRPE) have been described in association with familial adenomatous polyposis (FAP). Histopathologic findings have suggested a generalized effect of the FAP gene on the RPE, which could impair the functional integrity of the RPE. The clinical, psychophysical, electrophysiologic, and fluorescein angiographic findings in CHRPE in subjects with FAP were assessed.
Methods: RPE function was assessed in 7 subjects with CHRPE and a family history of FAP. Four had documented FAP (mean age = 22.25 years) and the other three were siblings of affected subjects, with a 50% risk of developing FAP (mean age = 6.33 years). All subjects underwent comprehensive ophthalmologic examination.
Results: All subjects showed mild hyperopia (mean, +1.13 D; best corrected visual acuity, 20/20 or better). On perimetry, there were scotomas corresponding to some lesions. ERG showed normal rod, maximal, single-flash cone, and flicker responses. Light-dark ratio was within the normal range on EOG. Fluorescein angiography demonstrated normal retinal vasculature overlying the CHRPE lesions, which blocked background choroidal fluorescence. A normal choriocapillaris was observed through some hypopigmented lacuna.
Conclusion: CHRPE has been related to generalized expression of an abnormal gene in RPE, but its functional abnormalities tend to be localized.