The Role of Pigmentation in Foveal Pit Morphology: An SD-OCT Study

Abstract

Purpose: : There have been a few reports showing race and gender related differences in macular thickness as measured with OCT. Recently, we developed an automated metric to assess foveal morphology (depth, diameter, slope) and found significant variation in the contour of the foveal pit among individuals with normal vision. It is also known that a disruption in melanin biosynthesis (as occurs in albinism) interferes with normal foveal development, and results in foveal hypoplasia. Here we sought to assess how race and pigmentation relate to macular thickness and foveal morphology.

Methods: : One hundred sixty-two eyes of 81 healthy patients (45 female, 36 male) underwent retinal imaging with SD-OCT (Bioptigen, Inc. & Carl Zeiss Meditec, Inc.). Skin pigmentation was assessed based on the von Luschan scale, with subjective grading performed by two independent observers. Ethnicity and eye and hair color were also recorded. Central subfield thickness and average retinal thickness was recorded from the Cirrus macular volume scans. Foveal morphology was measured using previously described MatLab software.

Results: : Compared with Caucasians (n=47), Blacks (n=10) and Asians (n=21) had reduced central subfield thickness (p<0.0001 & p<0.0001, respectively). Central subfield thickness was also less (p<0.0001) in females(249.04 µm) than males (268.53 µm). Regarding foveal morphology, pit depth was significantly greater in Blacks (133.45 µm) than in Caucasians (111.66 µm) and Asians (113.55 µm). Pit diameter was significantly greater in Blacks (2.178 mm) and Asians (2.134 mm) than in Caucasians (1.874 mm). Pit depth and diameter was also significantly greater in females than in males (p=0.0197 and p=0.0139, respectively), but the magnitude of the difference was lower than the racial differences observed. When all subjects were examined together, we observed a significant correlation between composite pigmentation and pit depth/diameter (p<0.0001).

Conclusions: : Previously reported differences in retinal thickness appear to have at least 2 mechanisms - in females, the differences are likely due to global differences in retinal thickness, while racially observed differences in thickness are appear to be driven by differences in foveal pit morphology.

Keywords: imaging/image analysis: clinical • retina • clinical (human) or epidemiologic studies: systems/equipment/techniques