Abstract
Purpose:
Abnormal brown pigment - often in plaques - is a frequent sign in MacTel. Their extent is best demonstrated by fundus autofluoresence (AF) imaging, in which they appear as localized areas of decreased AF. Our aim was to investigate the characteristics of abnormal pigmentation in the natural history of MacTel.
Methods:
Patients with a confirmed diagnosis were selected based on good quality Spectralis images being available including 5 year follow-up imaging from the cohort of the MacTel Study. Color fundus, red-free and AF images recorded digitally were examined to confirm the presence of pigment and to exclude hemorrhage or atrophy. AF imaging was performed using Heidelberg Spectralis scanning laser ophthalmoscopes at 488nm. Where the presence of pigment was confirmed, its area was measured in AF images using the Region Finder Tool in Heidelberg Explorer.
Results:
144 eyes of 72 patients (30 males, 42 females) ranging in age 42-78 years (mean=60.9, SD=8.7) with average visual acuity of 64.7±17.2 letters were included. At baseline, 35 patients (50.7%) demonstrated pigment in both eyes, 34 cases (49.3%) were unilateral. Mean pigment area at baseline was in unilateral cases 0.080mm2 (range=0.006-0.349mm2, SD=0.084mm2, n=34), in bilateral cases 0.235mm2 (range=0.006-1.454mm2, SD= 0.290mm2, n=70). In bilateral cases there was a strong correlation between pigment area in right and left eyes (Pearson’s correlation coefficient r=0.750, p<001). Differences in pigment area between uni- and bilateral eyes were significant (t-test, p<0.01). A subset of 64 eyes of 32 patients with a follow up period of 5 years was analyzed for progression. In this subset, 14 cases were bilateral, 18 unilateral at baseline. 50% (n=9) of the unilateral group progressed to bilateral. Mean annual progression rate was in unilateral eyes 0.018mm2 (range=0-0.081mm2, SD=0.021mm2, n=36), in bilateral eyes 0.026mm2 (range=0.002-0.179mm2, SD=0.034mm2, n=28). Differences in growth rate between uni- and bilateral eyes and between fellow eyes in the bilateral group were not statistically significant.
Conclusions:
Pigment area size and growth rate are mostly symmetrical between fellow eyes. Affected area in unilateral eyes is significantly smaller. Pigment may be an indicator of disease severity, a comparison with other signs of the disease is warranted.
Keywords: 696 retinal degenerations: hereditary •
603 Muller cells •
701 retinal pigment epithelium