title: Short-term effects of overnight orthokeratology on corneal epithelial permeability and biomechanical properties.
abstract: OBJECTIVE
  To investigate the effects of 30 nights of overnight orthokeratology (OOK) on corneal epithelial permeability (Pdc) and corneal biomechanical properties.
  
  
  METHODS
  BE Retainer and Paragon CRT lenses were used. Visits were scheduled approximately 4 hours after awakening at baseline and after 1, 5, 10, 14, and 30 days of treatment. Pdc was measured at baseline and at day 30, whereas corneal biomechanical properties and visual acuities (VAs) were measured at all visits.
  
  
  RESULTS
  Thirty-nine neophytes and soft contact lens wearers completed the study. There was no difference in Pdc between baseline (ln[Pdc] [95% confidence interval (CI)] = -2.65 [-2.80 to -2.50]) and day 30 (ln[Pdc][CI] = -2.68 [-2.85 to -2.50]) (P = 0.88). Corneal hysteresis (CH) and corneal resistance factor (CRF) reduced significantly from baseline (CH [CI] = 10.89 [10.59-11.19] mm Hg and CRF [CI] = 10.35 [9.99-10.72] mm Hg) to day 30 (CH [CI] = 10.59 [10.31-10.87] mm Hg and CRF [CI] = 9.58 [9.26-9.89] mm Hg) (P = 0.001 for CH and P < 0.001 for CRF). Posttreatment VA did not reach baseline targets, and the difference was worse with low-contrast letters. Asian individuals (n = 18) had significantly worse VA than non-Asian individuals (n = 21) under most conditions through day 5, and the difference extended through day 14 with low-contrast letters under mesopic conditions. The percentage of participants who achieved 20/20 uncorrected was 17% Asian and 40% non-Asian individuals after day 1 and reached 69% Asian and 83% non-Asian individuals at day 30.
  
  
  CONCLUSIONS
  Thirty nights of OOK did not alter Pdc when measured 4 hours after awakening. OOK caused CH and CRF to decrease, but the changes were not clinically significant compared with diseased and postsurgical cases. Asian individuals, who had lower baseline CH in this study, responded slower to OOK based on early uncorrected VA and overrefraction measurements.
authors: Clinical Research Center, School of Optometry, University of California-Berkeley, Berkeley, CA, USA.
authors: Thao N
authors: TN
authors: Yeh
authors: Harry M
authors: HM
authors: Green
authors: Yixiu
authors: Y
authors: Zhou
authors: Julie
authors: J
authors: Pitts
authors: Britney
authors: B
authors: Kitamata-Wong
authors: Sophia
authors: S
authors: Lee
authors: Shiyin L
authors: SL
authors: Wang
authors: Meng C
authors: MC
authors: Lin
mesh_terms: D000293:Adolescent; D000328:Adult; D001696:Biomechanical Phenomena / Q000502:physiology*; D003261:Contact Lenses; D019781:Corneal Topography; D019573:Epithelium, Corneal / Q000378:metabolism*; D005260:Female; D019793:Fluorescein / Q000378:metabolism*; D005456:Fluorescent Dyes / Q000378:metabolism*; D015590:Fluorophotometry; D006801:Humans; D008297:Male; D009216:Myopia / Q000378:metabolism / Q000628:therapy*; D054158:Orthokeratologic Procedures; D010539:Permeability; D012029:Refraction, Ocular / Q000502:physiology; D019108:Tight Junctions / Q000502:physiology*; D014792:Visual Acuity / Q000502:physiology; D055815:Young Adult
chemical_list: D005456:Fluorescent Dyes; D019793:Fluorescein
keywords: corneal epithelial permeability; corneal hysteresis; higher-order aberrations; orthokeratology
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