Abstract
Abstract: :
Purpose. To compare lipofuscin (LF) levels in a population of ARM subjects with those in age - matched normal subjects. To test if LF accumulation is influenced by disease severity, as indicated by drusen and hyperpigmentation Methods. In a cross-sectional study, LF in 50 ARM patients between 59 and 83 years of age was compared to 61 age-matched normal controls. Subjects were divided into three age groups: A1, from 59 to 65.9 years, A2 from 66 to 72.9 and A3 from 73 to 83. One individual scored color fundus photographs from every subject for hyperpigmentation and drusen (type, number and confluence) in a 10° diameter field. LF fluorescence was measured spectrophotometrically in the fovea and at 7° temporal to the fovea (7T). Contribution of drusen, macular pigment, melanin and extraneous fluorophores were minimized by using an excitation at 550 nm; all measurements were individually corrected for media absorption. Results. LF levels measured at 7°T reflect LF levels throughout the posterior pole. In all age groups, LF levels at the fovea were highly correlated with, and lower than, those at 7°T (p<0.0001 for both). In comparison with normal A2 eyes, LF levels in A3 eyes were 23% and 21% lower at 7T and in the fovea, respectively (P<0.015 for both). Moreover, LF levels declined with severity of ARM. In all ARM age groups, LF levels declined with increasing number of drusen (P<0.0001), hyperpigmentation (P<0.0001) and/or drusen confluence (P<0.0001). In more advanced ARM patients with subconfluent or confluent soft drusen and hyperpigmentation, LF levels at 7T were 49%, 21% and 19% lower than age-matched normals in Groups A1, A2 and A3, respectively (P<0.0004, 0.06, 0.07). At the fovea, LF in these patients was decreased 49%, 7% and 18%, respectively (p=0.006, 0.56, 0.09). Conclusions. Evidence that LF levels decline with increasing ARM severity supports the concept that LF is a marker of disease progression. Highly significant correlations with markers of disease progression suggest that measurement of LF may contribute to rapid quantitative assessment of ARM status. The decline in LF with progression of ARM may result from chemical changes in lysosomes, lysing action of A2E, and/or photoreceptor death and subsequent loss of LF. This decrease does not rule out the possibility that ARM is initiated by excessive lipofuscin levels.
Keywords: age-related macular degeneration • retinal pigment epithelium • retina