Relationship of Types, Sizes of Astigmatism, and Uncorrected Visual Acuity With Emmetropia
Purpose
The appearance of toric intraocular lenses and LASIK surgery has led to increased opportunities for astigmatism correction. However, there are some problems such as residual astigmatism that causes vision impairment. Herein, we report the findings of a relationship between types, sizes of astigmatism and uncorrected visual acuity (UCVA) with emmetropia.
Methods
The subjects were 454 eyes conducted with visual acuity ≥20/20 and equivalent sphere power <±0.5D (142 men, 183women; average age, 57.7 ± 10.7 years) living in the regions located at the center of Japan who participated in the 7th National Institute for Longevity Sciences – Longitudinal Study of Aging (NILS-LSA). The data were used to classify patients based on age group (40,50,60,70,80’s), sex (male, female), The equivalent sphere power and refractive astigmatism were assessed using an autorefkeratometer, classified according to the astigmatism type (with-the-rule astigmatism, against-the-rule astigmatism, Oblique astigmatism) and analyzed in terms of size (-0.25,-0.5,-0.75,-1,-1.25D).
Results
UCVA (logMAR) increased significantly with larger size of astigmatism (F=6.97, p<0.0001) and age (F=12.2, p<0.0001). There was no difference between UCVA (logMAR) in women and in men. UCVA was significantly larger in eyes with against-the-rule astigmatism than with with-the-rule astigmatism. UCVA was significantly larger in eyes with with-the-rule astigmatism, oblique astigmatism, and against-the-rule astigmatism, in that order. (P for trend<0.05)
Conclusion
The findings of this study revealed association with the types of astigmatism and UCVA.