title: [Objective optical quality after orthokeratology].
abstract: OBJECTIVE
  To determine the changes of objective optical quality after orthokeratology.
  
  
  METHODS
  Prospective, self-controlled study. Optical quality, including objective scatter index (OSI), modulation transfer function (MTF) cutoff frequency, contrast visual acuity (CVA) and objective tear film quality, was assessed with the OQAS II instrument before and 1 week, 1 month, and 3 months after orthokeratology. Parameters of corneal astigmatism and e value from topography were also assessed. The data was analyzed using one-way ANOVA.
  
  
  RESULTS
  Cylinder refraction was (-0.39 ± 0.39)D, (-0.65 ± 0.57)D, (-0.79 ± 0.56)D, and (-0.81 ± 0.53) D, respectively, at the four timepoints, and there was a statistically significant difference between before and after therapy (P < 0.05). Uncorrected visual acuity was 3.97 ± 0.51, 4.95 ± 0.12, 5.00 ± 0.06, and 5.00 ± 0.05, respectively. The e value was 0.37 ± 0.24, -0.23 ± 0.42, -0.29 ± 0.39, and -0.30 ± 0.37, respectively. The negative values after therapy were significantly different from the value before therapy (P < 0.01). The corneal astigmatism in 3 mm diameter was (1.27 ± 0.75) D, (1.06 ± 0.69) D, (1.11 ± 0.68) D , and (1.15 ± 0.67) D, respectively. There was no significant difference in astigmatism between before and after therapy (P ≥ 0.05). After therapy, the OSI increased from 0.59 ± 0.47 before therapy to 0.99 ± 0.66 at 1 week, 1.47 ± 1.17 at 1 month, and 1.49 ± 1.03 at 3 months. The difference between pre- and post-therapy OSI values was statistically significant (P < 0.05). The MTF cutoff frequency decreased from (36.6 ± 12.0) cpd before therapy to (34.2 ± 8.9) cpd at 1 week, (27.9 ± 12.6) cpd at 1 month, and (27.7 ± 11.6) cpd at 3 months after therapy. The difference in MTF cutoff frequency between before and 1 month after therapy was statistically significant (P < 0.05). The 100% CVA, 20% CVA, and 9% CVA all declined after therapy, but there was no statistically significant difference between before and after therapy. The OSI of tear film quality was 1.27 ± 1.12, 2.09 ± 1.67, 2.07 ± 1.12, and 2.10 ± 1.33, respectively, and the difference was statistically significant between before and after therapy (P < 0.05).
  
  
  CONCLUSIONS
  After 3 months of orthokeratology, the corneal central astigmatism remained, and the e value became negative, while OSI increased, and MTF cutoff frequency and tear film quality declined. The alteration was more and more obvious along with the therapy within 1 month, and was not significant within the following month. After short-term corneal reshaping, the ocular optical quality declined in some degree, but the loss was acceptable.
authors: Qingdao Eye Hospital, Shandong Eye Institute, Shandong Academy of Medical Sciences, Qingdao 266071, China.
authors: Xianli
authors: X
authors: Du
authors: Qingdao Eye Hospital, Shandong Eye Institute, Shandong Academy of Medical Sciences, Qingdao 266071, China.
authors: Yanmin
authors: Y
authors: Han
authors: Qingdao Eye Hospital, Shandong Eye Institute, Shandong Academy of Medical Sciences, Qingdao 266071, China. Email: chminqd@163.com.
authors: Min
authors: M
authors: Chen
mesh_terms: D000704:Analysis of Variance; D001251:Astigmatism / Q000175:diagnosis / Q000628:therapy*; D015350:Contrast Sensitivity; D003315:Cornea / Q000473:pathology; D019781:Corneal Topography; D006801:Humans; D054158:Orthokeratologic Procedures; D011446:Prospective Studies; D013666:Tears / Q000502:physiology*; D013997:Time Factors; D014792:Visual Acuity