Measuring Retinal Thickness and Visual Acuity in Eyes with Different Types of Astigmatism in a Cohort of Hong Kong Chinese Adults.

Purpose: The purpose of this study was to investigate optical coherence tomography (OCT)-measured retinal thickness (RT) and best-corrected distance visual acuity (BCDVA) in eyes with different types of astigmatism.

Methods: This is a case-control study of 101 participants stratified into With-The-Rule (WTR; n = 41), Against-The-Rule (ATR; n = 25), and control (n = 35) groups by noncycloplegic subjective refraction. Inclusion criteria were ages between 18 and 45 years, spherical-equivalent (SE) refraction ≥-10.00 diopters (D), negative cylindrical power (CYL) ≤-0.75 D with axes of 0 to 30 degrees/150 to 180 degrees for WTR and 60 to 120 degrees for ATR, or CYL ≥-0.25 D for controls. Participants suffering from ocular diseases related to retinal defects, having a history of ocular surgery, with BCDVA >0.10 LogMAR, or poor OCT imaging quality were excluded. Fovea-centered scans were performed using spectral-domain OCT (SD-OCT), and RT automatically measured by the inbuilt software. Only right eyes were analyzed. Groups were matched for age, gender, SE, axial length, and corneal curvature.

Results: One-way ANOVA showed a significant difference in both BCDVA (P = 0.039) and macular RT (P = 0.028) among the three groups. Bonferroni's post hoc test revealed statistically significant between-group differences in BCDVA (WTR vs. controls, P = 0.041), as well as in RT at inner-nasal (WTR vs. ATR, P = 0.034) and outer-temporal subfields (WTR vs. controls, P = 0.042). BCDVA was positively associated with macular RT (r = 0.206, P = 0.041) after adjusting for age, gender, and axial length.

Conclusions: Greater RT and poorer BCDVA were found in eyes with WTR astigmatism. Our findings suggest that the effect of astigmatism on retinal thickness and BCDVA may vary depending on not only magnitude, but also axis of astigmatism.