Factors affecting corneal hysteresis in normal eyes.
BACKGROUND
To evaluate factors affecting corneal hysteresis (CH) in normal eyes.


METHODS
We examined 86 normal eyes of 43 healthy volunteers (age, 39.1 +/- 14.5 years (mean +/- standard deviation); range, 19 to 68 years; gender, 26 men, 60 women; manifest refraction, -2.25 +/- 2.89 diopters (D); range, -9.13 to 3.88 D). We quantitatively assessed the value of CH using an Ocular Response Analyzertrade mark (Reichert Ophthalmic Instruments). We carried out this measurement three times, and the average value was used for statistical analysis. Multiple regression analysis was used to assess the relevant factors of the CH.


RESULTS
The mean CH was 10.2 +/- 1.3 mmHg. Explanatory variables relevant to the CH were, in order of magnitude of influence, the central corneal thickness (CCT) (partial regression coefficient B = 0.022, p < 0.0001), and the intraocular pressure (IOP) (B = -0.119, p = 0.04). No significant correlation was seen with other clinical factors such as age, gender, manifest refraction, or mean keratometric readings.


CONCLUSIONS
Eyes with thinner CCT and eyes with higher IOP are more predisposed to have lower CH. Refractive surgeons should, from a biomechanical viewpoint, take not only CCT but also IOP into consideration before performing keratorefractive surgery.
Department of Ophthalmology, University of Kitasato School of Medicine, 1-15-1 Kitasato, Sagamihara, Kanagawa 228-8555, Japan. kamiyak-tky@umin.ac.jp
Kazutaka
K
Kamiya
Mana
M
Hagishima
Fusako
F
Fujimura
Kimiya
K
Shimizu
D000328:Adult; D000368:Aged; D001696:Biomechanical Phenomena; D003315:Cornea / Q000502:physiology*; D004547:Elastic Tissue / Q000502:physiology*; D004548:Elasticity / Q000502:physiology*; D005260:Female; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology; D008297:Male; D008875:Middle Aged; D055815:Young Adult