Effect of Myopic Defocus on the Retina and Choroid and Its Interaction with Defocus Regions, Diurnal Rhythm, and Accommodation

Abstract

Purpose

To explore the effect of defocus region and amount, diurnal rhythm, and accommodation on myopic defocus-induced changes in the retina and choroid.

Design

Four test lenses were used: single-vision soft contact lens (SVCL), bifocal spectacle lens (BSL) with +3.50 diopters (D) addition in the inferior visual field, defocus incorporated multiple segments lens (DIMS), and dual-focus contact lens (DFCL) with +2.00 D addition.

Participants

Twenty-one adults aged between 18 and 30 years, myopia between −1.00 D and −6.00 D, were included.

Methods

Four lenses were used in random order at 4 separate days for each participant. Participants underwent OCT and OCT angiography examinations after distance-viewing (4 m) and near-viewing (20 cm) for 20 minutes with 4 test lenses at both 10 am and 5 pm.

Main Outcome Measures

Retinal and choroidal thicknesses (RT and ChT) and vessel density were assessed.

Results

The changes in RT, retinal and choroidal vessel density were not significantly different between lenses or times (all P > 0.05). Choroidal thickness changes differed between lenses after near-viewing in both the morning and evening and after distance-viewing in the morning (all P < 0.05). Compared with SVCL, BSL, DIMS, and DFCL achieved lower ChT reductions (all P < 0.05), and BSL showed least reduction. No lenses completely inhibited ChT thinning after near-viewing.

Conclusions

Myopic defocus inhibited choroid thinning more effectively in the morning, and provided sufficient defocus in the superior retina was more effective. The amount of lens defocus in this study (+3.50 D) was insufficient to inhibit choroidal thinning with 5 D accommodation completely.

Financial Disclosure(s)

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.