Abstract
Purpose :
Previous studies have shown that bifocal or multifocal lenses for myopia control increase the depth of focus (DoF) at the periphery. Increased peripheral DoF has been suggested to reduce the ability of the visual system to detect myopic or hyperopic defocus. We sought to determine the effects of increased peripheral DoF on short-term changes in choroidal thickness.
Methods :
The temporal 15° retina was exposed to a video stimulus (±4° horizontal & ±3° vertical visual field) for 30 minutes without exposing the fovea under two experimental conditions: increased DoF with a 2mm aperture and reduced depth of focus with a 6mm aperture. For all conditions, the eye’s peripheral lower-order and higher-order aberrations were corrected using a custom-built adaptive optics visual simulator after cycloplegia. Under each condition, subjects were exposed to the stimulus with induced myopic and hyperopic defocus. OCT scans in the exposed visual field were obtained using Heidelberg Spectralis OCT at 0, 10, 20, & 30 minutes after exposure in each condition. The choroidal thickness (ChT) was automatically segmented with a MATLAB program using a deep-learning neural network. Three subjects from a previous larger dataset containing 11 subjects were examined.
Results :
With the 6mm aperture condition, the larger dataset of 11 subjects showed lower choroidal thickness changes which were not statistically significant from baseline under both myopic and hyperopic defocus conditions [Average thickness (μm) for Myopic defocus: -7.1, -5.7, 0.9; Average thickness (μm) for Hyperopic defocus: -2.1, 1.22, & 1.72 – for 10, 20, & 30 minutes]. In three randomly selected subjects from the subject group, under increased depth of focus, the choroidal response consistently exhibited unidirectional thinning from baseline for both defocus conditions [ average thickness ± SEM μm (myopic defocus): -16.6 ± 6.9, -10.7 ± 5.7 & -25.8 ± 6.6; average thickness ± SEM μm (hyperopic defocus): -8.1 ± 9.4, -8.9 ± 2.6, -19.3 ± 11.5 – for 10, 20, & 30 minutes].
Conclusions :
Preliminary results show that increasing the peripheral DoF using a small aperture elicits a short-term unidirectional response of the choroid as compared to a reduced depth of focus condition with all aberrations corrected. This behavior of the choroid in response to increased depth of focus needs to be further investigated in a larger subject group.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.