title: Comparison of ocular modulation transfer function determined by a ray-tracing aberrometer and a double-pass system in early cataract patients.
abstract: BACKGROUND
  The evaluation of retinal image quality in cataract eyes has gained importance and the clinical modulation transfer functions (MTF) can obtained by aberrometer and double pass (DP) system. This study aimed to compare MTF derived from a ray tracing aberrometer and a DP system in early cataractous and normal eyes.
  
  
  METHODS
  There were 128 subjects with 61 control eyes and 67 eyes with early cataract defined according to the Lens Opacities Classification System III. A laser ray-tracing wavefront aberrometer (iTrace) and a double pass (DP) system (OQAS) assessed ocular MTF for 6.0 mm pupil diameters following dilation. Areas under the MTF (AUMTF) and their correlations were analyzed. Stepwise multiple regression analysis assessed factors affecting the differences between iTrace- and OQAS-derived AUMTF for the early cataract group.
  
  
  RESULTS
  For both early cataract and control groups, iTrace-derived MTFs were higher than OQAS-derived MTFs across a range of spatial frequencies (P < 0.01). No significant difference between the two groups occurred for iTrace-derived AUMTF, but the early cataract group had significantly smaller OQAS-derived AUMTF than did the control group (P < 0.01). AUMTF determined from both the techniques demonstrated significant correlations with nuclear opacities, higher-order aberrations (HOAs), visual acuity, and contrast sensitivity functions, while the OQAS-derived AUMTF also demonstrated significant correlations with age and cortical opacity grade. The factors significantly affecting the difference between iTrace and OQAS AUMTF were root-mean-squared HOAs (standardized beta coefficient = -0.63, P < 0.01) and age (standardized beta coefficient = 0.26, P < 0.01).
  
  
  CONCLUSIONS
  MTFs determined from a iTrace and a DP system (OQAS) differ significantly in early cataractous and normal subjects. Correlations with visual performance were higher for the DP system. OQAS-derived MTF may be useful as an indicator of visual performance in early cataract eyes.
authors.affiliation: Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University; Beijing Ophthalmology & Visual Science Key Laboratory, Capital Medical University, Beijing 100730, China.
authors.forename: Liya
authors.initials: L
authors.lastname: Qiao
authors.affiliation: Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University; Beijing Ophthalmology & Visual Science Key Laboratory, Capital Medical University, Beijing 100730, China.
authors.forename: Xiuhua
authors.initials: X
authors.lastname: Wan
authors.affiliation: Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University; Beijing Ophthalmology & Visual Science Key Laboratory, Capital Medical University, Beijing 100730, China.
authors.forename: Xiaogu
authors.initials: X
authors.lastname: Cai
authors.affiliation: College of Optometry, Midwestern University, Glendale, Arizona, United States.
authors.forename: Balamurali
authors.initials: B
authors.lastname: Vasudevan
authors.affiliation: Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University; Beijing Ophthalmology & Visual Science Key Laboratory, Capital Medical University, Beijing 100730, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Xiong
authors.affiliation: Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University; Beijing Ophthalmology & Visual Science Key Laboratory, Capital Medical University, Beijing 100730, China.
authors.forename: Jiaxuan
authors.initials: J
authors.lastname: Tan
authors.affiliation: Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University; Beijing Ophthalmology & Visual Science Key Laboratory, Capital Medical University, Beijing 100730, China.
authors.forename: Zheng
authors.initials: Z
authors.lastname: Guan
authors.affiliation: School of Optometry & Vision Science and Institute of Health & Biomedical Innovation, Queensland University of Technology, Australia.
authors.forename: David A
authors.initials: DA
authors.lastname: Atchison
authors.affiliation: Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University; Beijing Ophthalmology & Visual Science Key Laboratory, Capital Medical University, Beijing 100730, China. Email: wningli@vip.163.com.
authors.forename: Ningli
authors.initials: N
authors.lastname: Wang
mesh_terms: D057128:Aberrometry / Q000379:methods*; D000328:Adult; D000368:Aged; D002386:Cataract / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D014792:Visual Acuity / Q000502:physiology