Abstract
Purpose :
To investigate the optical coherence tomography (OCT) measured retinal thickness (RT) and best-corrected visual acuity (BCVA) in eyes with different types of astigmatism.
Methods :
This retrospective, case-control study was conducted at the Optometry Clinic of Hong Kong Polytechnic University. Subjects were stratified into with-the-rule (WTR), against-the-rule (ATR) and control groups by noncycloplegic subjective refraction. Inclusion criteria were: age between 18-45 years, spherical-equivalent refraction (SE) ≥ -10.00 D, cylindrical power (Cyl) ≤ -0.75 D with cylindrical axes of 0-30°/150-180° for WTR and 60-120° for ATR, and Cyl ≥ -0.25 D for the control group. Those eyes with any ocular disease that may cause retina defect, previous history of ocular surgery, BCVA > 0.1 LogMAR or poor imaging quality were excluded. BCVA were determined with Snellen charts and converted into LogMAR. The fovea-centred 6-mm scan was performed by SD-OCT (Spectralis OCT, Heidelberg), and RT was measured automatically by the inbuilt Heidelberg software, then manually checked and corrected by an experienced operator. Both corneal curvature and SE were used to adjust the magnification factor in OCT imaging.
Results :
In total, 101 subjects met the inclusion criteria and only right eyes were analysed (WTR, n=41; ATR, n=25; Controls, n=35). There were no significant differences in age, gender, SE, corneal curvature and intraocular pressure across three groups (all P > 0.05). One-way ANOVA showed a significant difference in both BCVA (P = 0.046) and global RT in 6-mm macula (P = 0.031) among the three groups. Bonferroni’s post hoc tests showed that the between-group difference in BCVA (WTR vs Controls, P = 0.041), as well as those differences in RT at inner-nasal (WTR vs ATR, P = 0.034) and outer-temporal (WTR vs Controls, P = 0.042) were statistically significant. BCVA was positively correlated with global RT (r = 0.310, P = 0.002) after adjusting for age, gender, SE, and corneal curvature.
Conclusions :
A thicker RT and poorer BCVA were found in eyes with WTR astigmatism in Chinese young adults, compared with the ATR and control groups. Our findings suggest that the effect of astigmatism on ocular morphological and functional characteristics may vary depending on not only magnitude but axes of astigmatism.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.