Abstract
Purpose :
Melanin is a major contributor to the intensity and width of the retinal pigment epithelium (RPE) on optical coherence tomography (OCT). It is hypothesized, high melanin concentrations cause scattering making the RPE appear as a thick band and obscures adjacent layers. A split band appearance of the outermost hyperreflective band has been demonstrated in Albinism, meaning the RPE and Bruch’s Membrane appear as two separate bands. We performed a cross-sectional observational study to test the hypothesis that a reduction in melanin causes an increased ability to differentiate the hyperreflective bands seen on OCT images of the outer retina.
Methods :
Using the UK Biobank dataset, we generated a randomised sample of 300 participants with specific inclusion and exclusion criteria. Inclusion criteria was an age between 40 to 65, visual acuity better than 0.60 logMAR, no ocular pathology, and measurable OCT images of both eyes. We analysed three ethnic groups: White (n=100), Asian (n=100) and Black (n=100). The OCT images of the participants’ left eyes were qualitatively analysed for the number of outer retinal hyperreflective bands at the fovea and parafovea. We also analysed the proportion of cases with foveal hypoplasia (FH). FH was graded using the Leicester OCT structural grading system described by Thomas MG et al. 2011.
Results :
A significantly less number of outer retinal hyperreflective bands are seen at the fovea (X2=7.23, p=0.027) and parafovea (X2=16.24, p=0.0003) in the black ethnicity group compared to the other ethnicity groups. Although there was a higher proportion of cases of grade 1 FH in the white and asian groups compared to the black group this was not statistically significant (p=0.09). No significant (p=0.69) difference in visual acuity is observed between the groups.
Conclusions :
We highlight the potential role of melanin in our ability to resolve outer retinal structures using OCT. Higher concentrations of melanin in black populations could be associated with fewer outer retinal hyperreflective bands. As previously described in albinism, the additional outer retinal bands visible are likely due to hypopigmentation. Outer retinal thickness measurements should be interpreted with caution when derived from automated segmentation algorithms.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.