Application of New Imaging Technologies in High Myopic Eyes

Abstract

Purpose : High myopia is a growing epidemic world-wide and is the subject of extensive scientific efforts. The tools available to scientists are mostly limited to refractive error, axial length, central choroidal thickness, and peripheral refraction. These tools provide mainly single measurement points, are difficult and time-consuming to administer, have limited availability, or are expensive. We demonstrate how new ophthalmic imaging technologies can provide better data for high myopic eyes over a large 90-degree field of view (FOV), including choroidal thickness, retinal curvature, and peripheral refraction maps.

Methods : Retinal curvature and choroidal thickness were assessed using a prototype 200kHz swept-source optical coherence tomography system (OCT) with a 90-degree FOV and segmentation software. Retinal curvature was estimated using the method described by Steidle in Photonic Solutions for Better Health Care VI (2018). Peripheral refraction was measured using a CLARUS^TM 500 fundus imager (ZEISS, Dublin, CA) with prototype software, using the method described by Everett (ARVO 2018). To validate the results, we created models of individual human eyes by customizing the Arizona Eye Model using measured axial eye length, refractive error, corneal power, and retinal curvature (Fig 2). Simulated peripheral refraction was compared to the measurement.

Results : A total of 42 eyes of 21 subjects were enrolled in the study ranging in axial length from 21.92 to 29.81mm. 90-degree FOV OCT scans were acquired in 26 eyes of 13 subjects. Choroidal thickness ranged from 93 to 440 microns, retinal radius of curvature from 10.8 to 16.0mm. Peripheral refraction was measured in 42 eyes of 21 subjects and ranged from -2.15 to +9.0 diopters. Simulation and measurement of peripheral refraction were matched within +/- 3D.

Conclusions : Wide-field fundus imaging and OCT enable new methods for measuring large FOV choroidal thickness, retinal curvature, and peripheral refraction. These technologies will help to further advance our knowledge of high myopia, myopia progression, and myopia treatment.

This abstract was presented at the 2019 ARVO Imaging in the Eye Conference, held in Vancouver, Canada, April 26-27, 2019.

 

Fig. 1(a) Estimation of retinal curvature and segmentation of retinal layer boundaries. (b) Relative peripheral refraction.

 

Fig. 2: Simulation of an individual human eye, modelling refractive error and peripheral refraction. (a) layout of the optical model showing cornea, crystalline lens, and retina. (b) Respective spot diagrams on-axis and off-axis.