Effect of astigmatism and spherical equivalent correction on contrast sensitivity

Area of Science:

• Ophthalmology
• Optometry
• Vision Science

Background:

• Astigmatism is a common refractive error affecting visual quality.
• Contrast sensitivity (CS) is a crucial measure of visual function.
• Understanding the impact of astigmatism correction on CS is vital for optimizing visual outcomes.

Purpose of the Study:

• To evaluate the influence of astigmatism and spherical equivalent (SE) correction on contrast sensitivity.
• To compare the effectiveness of full astigmatism correction versus SE correction on CS.

Main Methods:

• A cross-sectional study involving 103 visually normal subjects with regular astigmatism (1.00-4.00 DC).
• Binocular CS was measured using sine-wave gratings at various spatial frequencies (1.5-18 cpd).
• CS was assessed before correction, after full cylindrical correction, and after SE correction.

Main Results:

• Uncorrected astigmatism correlated with reduced CS, especially at high spatial frequencies.
• Significant CS improvements were observed with both SE and full cylindrical correction across most frequencies (P<0.001).
• At 18 cpd, no significant CS difference was found between uncorrected and SE-corrected states.

Conclusions:

• Binocular astigmatism negatively impacts CS, with correction improving visual quality.
• Full cylindrical correction may not maximize CS at higher spatial frequencies (12 & 18 cpd).
• SE correction effectively enhances CS for lower astigmatism degrees (<2.00 DC), particularly at lower frequencies.