Abstract
Purpose: :
To investigate the variation in high-order ocular wavefront aberration (WA) and sampling limit of resolution of the cone mosaic (Nc) in a population of young healthy subjects.
Methods: :
An Adaptive Optics retinal camera prototype (rtx1, Imagine Eyes, Fr) was used to image the cone mosaic in 12 subjects (age 24-28 years, axial length 22.61-26.63 mm, 24 eyes). Cone density and Nc were calculated at fixed eccentricity between 260 µm and 600 µm from the foveal center. The ocular WA was measured using the OPD scan II (Nidek, Japan). The Coefficient of Variation (CoV) was used to analyze the variation of optical and retinal parameters. Correlation of optical and retinal parameters with AxL was performed using the Pearson analysis.
Results: :
A high inter-individual variance of the high-order WA was found, ranging from 26% for corneal high-order aberrations (HOA) to 43% for intraocular HOA. The CoV of cone density and Nc was 16% and 5% at all retinal eccentricities respectively. The reduction in cone density and Nc with axial length was statistically significant at each retinal eccentricity (R2=0.65, P<0.001).
Conclusions: :
Though there appears to be a random variation in the eye optical WA from subject to subject, the cone packing density and Nc are highly correlated to axial length. The Nyquist limit of resolution of the cone mosaic is reduced with increasing axial length.
Keywords: imaging/image analysis: clinical • myopia