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 studywas 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 wavefrontaberration was analyzed.Results As the dioptric power of astigmatism increased,the loss of CS spatial frequency changed from high tointermediate,and then to low frequency.CS scores varied at different illuminance levels,descending in the followingsequence:photopia,photopia with glare,scotopia,and scotopia with glare.However,the normal accommodation groupshowed better CS values under photopia with glare than without glare.The range of influenced direction of sine-wavegratings remained mostly at the meridian line of high dioptric power,which would be expanded when opticalaccommadation attenuated.The patients with symmetrical astigmatism got higher CS scores with binoculus vision thanwith dominant eye vision,while the patients with asymmetrical astigmatism did this only at scotopia with glare.Amonghigher-order aberrations,coma aberration,secondary coma aberration and the total higher order aberration wereinfluenced 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 ofastigmatism should be cut down,but also the binocular axes should be made symmetrically.