Contrast sensitivity and higher-order aberrations in patients with astigmatism.
BACKGROUND
Astigmatism is one of the most significant obstacles for achieving satisfactory visual function. This study was to evaluate the influence of astigmatism on contrast sensitivity (CS) and higher-order aberrations.


METHODS
CS, accommodation response and wavefront aberration were measured in 113 patients with astigmatism, aged 18 - 36 years. Both single and binocular visual performance were examined under four lighting conditions: photopia, photopia with glare, scotopia and scotopia with glare respectively. Accommodation response was classified as normal, abnormal and low. The contribution of the power and axis of astigmatism to CS, accommodation response and wavefront aberration was analyzed.


RESULTS
As the dioptric power of astigmatism increased, the loss of CS spatial frequency changed from high to intermediate, and then to low frequency. CS scores varied at different illuminance levels, descending in the following sequence: photopia, photopia with glare, scotopia, and scotopia with glare. However, the normal accommodation group showed better CS values under photopia with glare than without glare. The range of influenced direction of sine-wave gratings remained mostly at the meridian line of high dioptric power, which would be expanded when optical accommadation attenuated. The patients with symmetrical astigmatism got higher CS scores with binoculus vision than with dominant eye vision, while the patients with asymmetrical astigmatism did this only at scotopia with glare. Among higher-order aberrations, coma aberration, secondary coma aberration and the total higher order aberration were influenced by astigmatism, all of which rising with the power of astigmatism increased.


CONCLUSIONS
Reducing astigmatism might improve the performance of visual function. Not only the power of astigmatism should be cut down, but also the binocular axes should be made symmetrically.
Zheng
Guang-ying
GY
Department of Ophthalmology, First Affiliated Hospital, Zhengzhou University, Zhengzhou 450052, China. zzzgy@zzu.edu.cn
Du
Jun
J
Zhang
Jin-song
JS
Liu
Su-bing
SB
Nie
Xiao-li
XL
Zhu
Xiao-hong
XH
Tang
Xiu-xia
XX
Xin
Bao-li
BL
Mai
Zhi-bin
ZB
Zhang
Wei-xia
WX
D000293:Adolescent; D000328:Adult; D001251:Astigmatism / Q000503:physiopathology*; D015350:Contrast Sensitivity; D005260:Female; D006801:Humans; D008297:Male; D014785:Vision, Ocular