title: [Comparison of ocular modulation transfer function measurements by ray tracing wavefront technology and double-pass system].
abstract: OBJECTIVE
  To compare the agreement of the ocular modulation transfer function (MTF) measured by double-pass system and ray tracing wavefront aberrometry, and to analyze the correlations of two MTFs with the visual acuity and contrast sensitivity function results.
  
  
  METHODS
  Comparative study. Subjects with no ocular diseases were consecutively enrolled in an epidemic study field located at the Dongyangzhuang Health Center, Yongnian County, Handan City, Hebei Province, China. After comprehensive ophthalmic examinations, the mean values of subtracted lower order aberration MTF at 5, 10, 15, 20, 25, and 30 cycle/degree(c/d) spatial frequencies were obtained with a double-pass system (optical quality analysis system II, OQAS II system) and a ray tracing wavefront aberrometer (iTrace visual function analyzer, iTrace system) in the 4.0 mm and 6.0 mm pupil after dilation, respectively. Paired-sample t test and Bland-Altman analysis were used to compare the difference and agreement of MTFs obtained with two instruments. Correlation analysis was preformed between two MTF measurement results and subjective visual quality including visual acuity and contrast sensitivity function.
  
  
  RESULTS
  Two hundred and fifty-one healthy eyes of 163 subjects were enrolled, aged 30 to 60, mean (44.1 ± 9.7) years, including 139 eyes of 81 males and 112 eyes of 82 females. The mean value of MTF at 5, 10, 15, 20.25, 30 c/d obtained by iTrace in 4.0 mm pupil were 0.730 ± 0.138, 0.431 ± 0.159, 0.262 ± 0.120, 0.169 ± 0.078, 0.118 ± 0.053, 0.094 ± 0.043. The value obtained by OQASII were 0.347 ± 0.123, 0.162 ± 0.086, 0.072 ± 0.049, 0.042 ± 0.033, 0.026 ± 0.022, 0.017 ± 0.022, The result of iTrace were all significant higher than OQAS in both 4mm(t = 38.72, 28.03, 27.32, 27.59, 29.23, 28.96, P < 0.01) and 6.0 mm(t = 4.60, 3.19, 9.34, 13.41, 16.96, 20.24, P < 0.01)pupil diameter. The iTrace-OQAS II MTF difference was smaller in the 6.0 mm pupil. Bland-Altman analysis indicated that the agreement of two instruments was poor, while the limits of agreement improved in the 6.0 mm pupil. The iTrace-derived MTFs were negatively correlated with the subjects' LogMAR best corrected visual acuity (r = -0.139--0.165, P < 0.01) and positively with the log value of contrast sensitivity function at 6 c/d (P < 0.05) . OQAS-derived MTFs were negatively correlated with LogMAR best corrected visual acuity (r = 0.239-0.303, P < 0.01) and positively with contrast sensitivity at all spatial frequencies (r = 0.156-0.398, P < 0.01) .
  
  
  CONCLUSIONS
  There exists a significant difference and poor agreement in MTF measurement based on the ray tracing wavefront aberrometer and the double-pass system, while the difference becomes smaller in a large pupil diameter. The double-pass system provides a useful tool in clinical optical quality evaluation.
authors: Beijing Ophthalmol & Visual Sciences Key Laboratory,Beijing Institute of Ophthalmology,Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University,Beijing 100730, China.
authors: Liya
authors: L
authors: Qiao
authors: Beijing Ophthalmol & Visual Sciences Key Laboratory,Beijing Institute of Ophthalmology,Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University,Beijing 100730, China.
authors: Xiaogu
authors: X
authors: Cai
authors: Beijing Ophthalmol & Visual Sciences Key Laboratory, Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing 100730, China.
authors: Xiuhua
authors: X
authors: Wan
authors: Beijing Ophthalmol & Visual Sciences Key Laboratory, Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing 100730, China.
authors: Zheng
authors: Z
authors: Guan
authors: Beijing Ophthalmol & Visual Sciences Key Laboratory, Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University,Beijing 100730, China.
authors: Ying
authors: Y
authors: Xiong
authors: Beijing Ophthalmol & Visual Sciences Key Laboratory,Beijing Institute of Ophthalmology,Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University,Beijing 100730, China.
authors: Zhong
authors: Z
authors: Lin
authors: Beijing Ophthalmol & Visual Sciences Key Laboratory,Beijing Institute of Ophthalmology,Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University,Beijing 100730, China.
authors: Ye
authors: Y
authors: Zhang
authors: Beijing Ophthalmol & Visual Sciences Key Laboratory,Beijing Institute of Ophthalmology,Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University,Beijing 100730, China.
authors: Jiaxuan
authors: J
authors: Tan
authors: Beijing Ophthalmol & Visual Sciences Key Laboratory,Beijing Institute of Ophthalmology,Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University,Beijing 100730, China. Email:wningli@vip.163.com.
authors: Ningli
authors: N
authors: Wang
mesh_terms: D000328:Adult; D002681:China; D015350:Contrast Sensitivity / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011680:Pupil / Q000502:physiology; D014786:Vision Disorders / Q000503:physiopathology / Q000628:therapy*; D014792:Visual Acuity / Q000502:physiology*