title: Central corneal thickness and corneal hysteresis during corneal swelling induced by contact lens wear with eye closure.
abstract: OBJECTIVE
  To determine if corneal hysteresis (CH) was associated with increased central corneal thickness (CCT) induced by wearing soft contact lenses during eye closure.
  
  
  METHODS
  A prospective laboratory investigation.
  
  
  METHODS
  CCT was measured with a modified optical coherence tomography (OCT), and CH was measured with a Reichert Ocular Response Analyzer (ORA) [Reichert Ophthalmic Instruments, Depew, New York, USA]. The ORA also determined values for intraocular pressure (IOP), corneal compensated IOP (IOPcc), and corneal resistance factor (CRF). One randomly selected eye of 20 non-contact lens wearers (four males and 16 females, age 19.7 +/- 1.1 years) was patched during three hours of soft contact lens wear. Measurements were made before lens insertion, immediately upon removal, and every 20 minutes thereafter for 100 minutes.
  
  
  RESULTS
  Immediately after contact lens removal, CCT was increased by 13.1 +/- 2.2% (mean +/- SD) compared with baseline (post hoc, P = .001). After 100 minutes, it remained elevated by 2.4 +/- 1.6% (post hoc, P = .001). However, there were no significant differences of CH at any time after lens wear (analysis of variance [ANOVA], P = .9). Immediately after lens removal, there were significant increases in IOP (post hoc, P = .003) and corneal resistance factor (CRF) (post-hoc, P = .015), but not in IOPcc (post hoc, P = .07). After lens wear, there were significant but weak correlations between the percentage change of CCT (CCT%) and IOP (r = 0.32, P = .001) and IOPcc (r = 0.29, P = .001). However, there was no significant correlation between CCT% and CH (r = 0.07, P = .458).
  
  
  CONCLUSIONS
  CH as measured by ORA was not associated with corneal swelling induced by soft contact lens wear in this study group.
authors.affiliation: School of Ophthalmology and Optometry, Wenzhou Medical College, Wenzhou, Zhejiang, China.
authors.forename: Fan
authors.initials: F
authors.lastname: Lu
authors.forename: Suzhong
authors.initials: S
authors.lastname: Xu
authors.forename: Jia
authors.initials: J
authors.lastname: Qu
authors.forename: Meixiao
authors.initials: M
authors.lastname: Shen
authors.forename: Xiaoxing
authors.initials: X
authors.lastname: Wang
authors.forename: Haizhen
authors.initials: H
authors.lastname: Fang
authors.forename: Jianhua
authors.initials: J
authors.lastname: Wang
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D003263:Contact Lenses, Hydrophilic / Q000009:adverse effects*; D003315:Cornea / Q000473:pathology*; D015715:Corneal Edema / Q000175:diagnosis* / Q000209:etiology; D004547:Elastic Tissue; D005260:Female; D006801:Humans; D007429:Intraocular Pressure; D008297:Male; D011446:Prospective Studies; D012683:Sensory Deprivation; D041623:Tomography, Optical Coherence