Abstract
Purpose: :
The influence of central corneal thickness (CCT) on intraocular pressure measurement has recently been paid attention; however, CCT measurements fluctuate considerably, depending on various factors. To clarify those factors, we investigated the seasonal variation of CCT in various types of glaucoma patients.
Methods: :
This study was conducted as a retrospective single–center, observational case–control study. Total number of 1876 patients who visited Glaucoma Service in Kyoto Prefectural University of Medicine Hospital and measured CCT from September 1995 to November 2005 was retrospectively investigated. Most of the patients were medicated with anti–glaucoma drugs if necessary. CCT was measured using ultrasound pachymeter (IOPac, Heidelberg engineering) or Pentacam (Oculus) in clinical setting, and averaged every 3 months to represent the each season (spring; Mar, Apr, May, summer; Jun, Jul Aug, autumn; Sep, Oct, Nov, winter; Dec, Jan, Feb). Seasonal variation of CCT was evaluated from the CCT differences among each season. For statistical analysis, unpaired t test was used.
Results: :
Averaged CCT becomes thicker in winter (546.4 +/– 40.8) and thinner in summer (539.0 +/– 39.3 micro meter) and the differences were statistically significant (p<0.0001). The averaged CCT in ocular hypertension patients were significantly thicker than other types of glaucoma. In all types of glaucoma, winter CCT has a thicker tendency than summer CCT.
Conclusions: :
There is a seasonal variation in CCT as well as intraocular pressure, however the effects were considered to be relatively small.
Keywords: clinical (human) or epidemiologic studies: biostatistics/epidemiology methodology • intraocular pressure • cornea: clinical science