Abstract
Abstract: :
Purpose: Fundus autofluorescence (FAF) imaging provides indirect information on the level of metabolic activity of the retinal pigment epithelium (RPE) by imaging lipofuscin accumulation in the RPE largely determined by the rate of turnover of photoreceptor outer segments. In typical retinitis pigmentosa (RP) with abnormal fundus findings, reduced FAF is seen in areas of photoreceptor cell loss. A subset of patients with Leber congenital amaurosis (LCA), however, have near normal fundi. It is uncertain whether the photoreceptor/RPE–complex is still viable in such patients. Methods: Three adult patients with LCA (LCA1, 24 yrs; LCA2, 15 yrs and LCA3, 37 yrs) and one patient with typical RP (28 yrs) as a control were studied. LCA3 was the mother of LCA2. The diagnosis was based on history, visual function and Ganzfeld electroretinography according to the ISCEV standard. FAF was recorded with a cSLO (Heidelberg Retina Angiograph, HRA; Heidelberg Engineering, Heidelberg, Germany). Results: All LCA patients had vision reduced to perception of light and had undetectable ERGs. The fundus was near normal in LCA1 and LCA2. LCA3 showed irregular pigmentation at the level of the RPE. FAF was virtually normal in LCA1, near normal in LCA2, and moderately abnormal in LCA3. The RP patient showed preserved visual acuity, detectable but markedly abnormal ERGs, and profoundly abnormal FAF. Conclusions: The FAF findings in the LCA patients suggest that there is continuous metabolic demand from the photoreceptors and thus that these photoreceptors are anatomically intact with retinoid turnover, but have lost function. These findings may have implications for future treatment. It is remarkable that more than 20 years of severe visual impairment associated with LCA can be associated with normal FAF indicating that retinal function may be amenable to rescue.
Keywords: degenerations/dystrophies • retinal pigment epithelium • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)