Abstract
Purpose: :
Purpose: To examine the change in outer nuclear layer (ONL) thickness related to refractive error using spectral domain optical coherence tomography (SD-OCT).
Methods: :
Methods: We acquired 30 deg vertical scans through the fovea of the right eye for 69 subjects (42 female/27 male) with SD-OCT (Spectralis, Heidelberg Engineering): 26 hyperopic/emmetropic subjects (plano to +2.00) and 43 myopic subjects (-2.25 to -14.00). Central refractive error data and axial length were also measured (IOLMaster, Zeiss Meditec). All SD-OCT images were centered at the fovea. Axial length was used to correct for magnification effects. The junction between the outer plexiform layer/ONL and between the ONL/external limiting membrane were segmented out using a custom built Matlab program. The thickness between the layers was measure data every 0.5 degrees from 12 degrees below the fovea to 12 degrees above. Age was also analyzed for potential interaction with ONL thickness.
Results: :
Results: Within the central 2 degrees, ONL thickness was not significantly different between myopes and hyperopes. Between 2 degrees and 10 degrees, myopes exhibited relatively thinner ONL (65.54 microns) compared to emmetropes (76.43 microns) that was statistically significant (P < 0.0001). This was not due to age.
Conclusions: :
Conclusions: More quantification of individual differences is needed to determine if the thinning found in myopes is explained by to stretching of the retina associated with axial elongation. Alternatively, other factors to be examined include individual differences such as decreased photoreceptor density due to genetic or environmental differences. The existence of peripherally lower ONL thickness potentially provides a smaller stop signal for eye growth in the periphery of myopes.
Keywords: myopia • refractive error development • retina: distal (photoreceptors, horizontal cells, bipolar cells)