Abstract

INTRODUCTION:

Orthokeratology lenses flatten the center and steepen the peripheral portion of the cornea. These alterations cause the image to form in front of the peripheral retina and provides the feedback signal to slow axial growth. However, detailed two-dimensional spatial distribution of retina defocus has not been directly measured. This study aims to quantify this distribution at baseline and how it changes after receiving orthokeratology treatment.

METHODS:

Retina defocus was measured through the use of Multispectral Refraction Topography which produced a retinal fundus picture with 128 x 128 grids for analysis. Topography maps were broken down into rings labeled center, middle, and periphery and plotted as a sinusoidal waveform. The Fourier Transformation was applied to each waveform to decompose them into a summation of sinewaves. Three parameters (F0, F1, and Vmin) were extracted for analysis.

OUTCOMES:

The mean age was 15.11 ± 7.76 and mean refractive errors were -2.57 ± 0.88 diopters (N = 80). Parameters F0, F1, and Vmin all became significantly smaller (p < 0.001) after orthokeratology treatment. However, F1/F0 ratio became significantly larger (p < 0.001).

DISCUSSION:

This study could aid in retardation of myopic progression by providing new insight into the detailed spatial distribution of retinal defocus caused by orthokeratology lenses. Further research is required into spatial distributions of retinal defocus that maximize retardation of axial length growth. This will require follow-up with these patients at one year of orthokeratology treatment with the overall goal of providing data that is useful for future orthokeratology lens design.