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Optical quality in low astigmatic eyes with or without cylindrical correction
Qing-Qing Tan1,2, Bai-Wei Wen1,2, Xuan Liao1,2
1Department of Ophthalmology, Affiliated Hospital of North Sichuan Medical College, 1 Mao Yuan Nan Road, Nanchong, 637000, Sichuan, China.
Summary
Cylindrical correction improves optical quality and visual acuity for low myopic astigmatism, especially against-the-rule (ATR) and oblique (OBL) types. Improvement is limited for with-the-rule (WTR) astigmatism below -0.75 D.
Area of Science:
- Ophthalmology
- Optometry
- Vision Science
Background:
- Low levels of myopic astigmatism are common in young, healthy eyes.
- The impact of correcting low astigmatism on overall optical quality is not fully understood.
- Understanding optimal correction strategies is crucial for visual performance.
Purpose of the Study:
- To determine if cylindrical correction enhances optical quality in myopic eyes with low astigmatism (-0.50 to -0.75 D).
- To evaluate the effect of astigmatism axis (WTR, ATR, OBL) on the benefits of cylindrical correction.
- To compare visual acuity and optical quality metrics between spherical and spherocylindrical corrections.
Main Methods:
- A cross-sectional study included 194 healthy young eyes with myopia (-3.00 D) and low astigmatism (-0.50 to -0.75 D).
- Each eye was evaluated using both spherocylindrical and spherical corrections via subjective refraction.
- Optical quality was assessed using objective scatter index (OSI), MTF cut-off, Strehl ratio (SR), and simulated contrast visual acuity (OV); corrected distance visual acuity (CDVA) was also measured.
Main Results:
- Spherocylindrical correction significantly improved CDVA for most astigmatism types, except for -0.50 D WTR astigmatism.
- For -0.50 D ATR and OBL astigmatism, spherocylindrical correction improved OSI, MTF cut-off, and OV, but not SR.
- All optical quality parameters and CDVA improved significantly with spherocylindrical correction for -0.75 D astigmatism, irrespective of axis.
Conclusions:
- Cylindrical correction benefits optical quality and visual acuity in eyes with low ATR or OBL myopic astigmatism (down to -0.50 D).
- For WTR astigmatism, significant improvements in optical quality and visual acuity are observed only when astigmatism exceeds -0.75 D.
- Spherocylindrical correction is recommended for low myopic astigmatism, particularly for ATR and OBL orientations, to optimize visual outcomes.
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