The effect of peripheral astigmatism and peripheral blur on visual field sensitivity thresholds

Abstract

Purpose : To investigate the effect of peripheral astigmatism and peripheral blur on visual field sensitivity using static automated perimetry.

Methods : Subjects were enrolled in two age-matched groups: phakic subjects (n=29) and pseudophakic subjects (n=31), who had been monocularly or bilaterally implanted with an aspherical monofocal intraocular lens (IOL) that fully compensates for the average corneal spherical aberration. Peripheral astigmatism and peripheral blur were measured using an open field autorefractor. The measurements were taken in 10-degree increments, ranging from 30 degrees nasal to 30 degrees temporal in the horizontal field. Visual sensitivity was measured with a visual field analyzer in two horizontal meridians: three degrees superior and three degrees inferior in steps of 6 degrees from 27 nasal to 27 degrees temporal. A linear mixed model was used to investigate if absolute peripheral astigmatism and if absolute peripheral blur impacts retinal sensitivity considering potential random effects of each participant, and fixed effects of status (phakic versus pseudophakic), eccentricity and nasal/temporal field side.

Results : Visual field sensitivity decreased, while peripheral astigmatism and peripheral blur increased with eccentricity. The changes were larger for pseudophakic than for phakic subjects. All parameters experienced a larger change with eccentricity in the nasal visual field than in the temporal field. Considering the random and fixed effects, the linear mixed model predicted significant decrease of visual field sensitivity with increased peripheral astigmatism, peripheral blur, and eccentricity with a substantial explanatory power (conditional R2=0.62 for peripheral astigmatism and R2=0.57 for peripheral blur). The individual participant, eccentricity, peripheral astigmatism and peripheral blur, and side of the field (nasal/temporal) were statistically significant (all p<0.01). Pseudophakia (p=0.08 for peripheral astigmatism and p=0.04 for peripheral blur) had a negative effect on visual field sensitivity up to -1.7dB which is clinically significant. A larger sample size would have offered the possibility of using interaction terms e.g. eccentricity with peripheral cylinder to improve the predictability of the model.

Conclusions : This study suggests that reducing astigmatism or blur in the periphery improves visual field sensitivity.

This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.