Foveal cone-photoreceptor integrity in aging macula disorder.
OBJECTIVE
To establish the relation between AMD stage and a quantitative measure for the integrity of foveal cone photoreceptors related to the optical Stiles-Crawford effect.


METHODS
Fifty-six AMD eyes and 57 control eyes were included in the final analysis. AMD was graded in accordance with the International Classification System into five mutually exclusive stages. Stages 0 to 1 were labeled no AMD, stages 2 to 3 were labeled early AMD, and stage 4 was labeled late AMD. Fundus reflectometry, together with a model-fit procedure, provided information on directional cone reflectance (Rd), a quantitative measure for the integrity of foveal cone photoreceptors. Optical densities of macular pigment (MPOD) and melanin (MOD) were also obtained. A general linear model analysis was used to compare Rd, MPOD, and MOD among the AMD stages.


RESULTS
Mean Rd was lower in early AMD (0.92%, P < 0.001) and late AMD (0.86%, P < 0.001) compared with mean Rd in the no-AMD stage (1.76%). Mean MPOD was not different in early AMD (0.53, P = 0.05), but it was lower in late AMD (0.19, P < 0.001) compared with mean MPOD in the no-AMD stage (0.42). Mean MOD was lower in early (1.09, P = 0.001) and late (1.01, P = 0.004) AMD compared with mean MOD in the no-AMD stage (1.23).


CONCLUSIONS
Foveal cones show signs of misalignment and/or outer segment deterioration in early AMD. Melanin rather than macular pigment may play a protective role against AMD, although loss of these ocular pigments can also be caused by AMD.
Kanis
Martijn J
MJ
Department of Ophthalmology, University Medical Center Utrecht, Utrecht, The Netherlands. m.j.kanis@umcutrecht.nl
Wisse
Robert P L
RP
Berendschot
Tos T J M
TT
van de Kraats
Jan
J
van Norren
Dirk
D
D000368:Aged; D000375:Aging / Q000502:physiology*; D005584:Fovea Centralis / Q000473:pathology*; D006801:Humans; D008027:Light; D008268:Macular Degeneration / Q000145:classification / Q000175:diagnosis* / Q000378:metabolism; D008543:Melanins / Q000378:metabolism; D008875:Middle Aged; D017949:Retinal Cone Photoreceptor Cells / Q000378:metabolism / Q000473:pathology* / Q000528:radiation effects; D012168:Retinal Pigments / Q000378:metabolism
D008543:Melanins; D012168:Retinal Pigments