title: Corneal volume measures for monitoring contact lens induced corneal swelling: a pilot study.
abstract: BACKGROUND
  This study investigated the use of corneal volume to monitor the corneal swelling response induced by wearing high plus power contact lenses.
  
  
  METHODS
  Twelve young non-contact lens wearers were recruited with one eye fitted with a soft contact lens (Polymacon material, 38.6 per cent water, Dk of 9 and 0.27 mm centre thickness) and the fellow eye served as control. The treated eye was patched for two hours leaving the control eye uncovered. Central corneal thickness (CCT) was measured with non-contact specular microscopy and corneal volumes (at three, five and 10 mm zones) were measured with a corneal topographer (Pentacam, Oculus Inc, Germany), before eye patching as well as immediately after and every 20 minutes for 100 minutes.
  
  
  RESULTS
  Subjects had similar CCT and corneal volumes between the two eyes before treatment. The treatment eyes showed a mean corneal swelling of 8.1 per cent immediately after lens removal. Corneal volume was significantly increased at the three (mean swelling of 5.9 per cent), five (5.6 per cent) and 10 millimetre (3.3 per cent) zones. It took 20 minutes for the corneal volume at the 10 mm zone to return to baseline but required 60 minutes for the three and five millimetre zones to return to the baseline level. The central corneal thickness was still significantly thicker 80 minutes after patching.
  
  
  CONCLUSIONS
  Corneal volume could be a useful parameter to monitor corneal change when an event affects the entire cornea. Corneal volume combined with central corneal thickness could give more comprehensive information to monitor central corneal swelling.
authors.affiliation: Centre for Myopia Research, School of Optometry, School of Optometry, The Hong Kong Polytechnic University, Hong Kong SAR, China. andrew.kc.lam@polyu.edu.hk
authors.forename: Andrew K C
authors.initials: AK
authors.lastname: Lam
authors.forename: Yin-zhi
authors.initials: YZ
authors.lastname: Wong
authors.forename: Suk-yi
authors.initials: SY
authors.lastname: Cheng
mesh_terms: D000328:Adult; D003263:Contact Lenses, Hydrophilic / Q000009:adverse effects*; D003315:Cornea / Q000473:pathology*; D015715:Corneal Edema / Q000209:etiology* / Q000473:pathology*; D019781:Corneal Topography; D005260:Female; D006801:Humans; D020100:Hydrogels; D008297:Male; D010865:Pilot Projects; D011102:Polyhydroxyethyl Methacrylate / Q000031:analogs & derivatives; D011159:Population Surveillance / Q000379:methods*; D055815:Young Adult
chemical_list: D020100:Hydrogels; C000257:polyhydroxyethyl methacrylate hydrogels; D011102:Polyhydroxyethyl Methacrylate