title: Contrast sensitivity and higher-order aberrations in patients with astigmatism.
abstract: 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.
authors.affiliation: Department of Ophthalmology, First Affiliated Hospital, Zhengzhou University, Zhengzhou 450052, China. zzzgy@zzu.edu.cn
authors.forename: Guang-ying
authors.initials: GY
authors.lastname: Zheng
authors.forename: Jun
authors.initials: J
authors.lastname: Du
authors.forename: Jin-song
authors.initials: JS
authors.lastname: Zhang
authors.forename: Su-bing
authors.initials: SB
authors.lastname: Liu
authors.forename: Xiao-li
authors.initials: XL
authors.lastname: Nie
authors.forename: Xiao-hong
authors.initials: XH
authors.lastname: Zhu
authors.forename: Xiu-xia
authors.initials: XX
authors.lastname: Tang
authors.forename: Bao-li
authors.initials: BL
authors.lastname: Xin
authors.forename: Zhi-bin
authors.initials: ZB
authors.lastname: Mai
authors.forename: Wei-xia
authors.initials: WX
authors.lastname: Zhang
mesh_terms: D000293:Adolescent; D000328:Adult; D001251:Astigmatism / Q000503:physiopathology*; D015350:Contrast Sensitivity; D005260:Female; D006801:Humans; D008297:Male; D014785:Vision, Ocular