Effect of aging on corneal biomechanical parameters using the ocular response analyzer

Purpose: To assess the effect of aging on corneal biomechanical parameters in a normal population.

Methods: We prospectively examined 204 normal eyes of 204 healthy Japanese volunteers (68 men, 136 women; mean age 46.7+/-19.4 years [range: 19 to 89 years]). Corneal hysteresis, corneal resistance factor, corneal-compensated intraocular pressure (IOP(cc)), and Goldmann-correlated intraocular pressure (IOP(G)) were qualitatively assessed using a Reichert Ocular Response Analyzer. Central corneal thickness was measured using an ultrasound pachymeter. This measurement was performed 3 times, and the mean value obtained was used for statistical analysis. The relationships between patient age and corneal biomechanical parameters, or age and intraocular pressure (IOP), were investigated.

Results: Mean corneal hysteresis and corneal resistance factor were 10.1+/-1.5 mmHg and 10.1+/-1.6 mmHg, respectively. Mean central corneal thickness was 539.1+/-30.9 microm. A weak, but significant, negative correlation was found between age and corneal hysteresis (Pearson's correlation coefficient r=-0.17, P=.02) and corneal resistance factor (r=-0.18 P=.01). On the other hand, no significant correlation was found between age and central corneal thickness (r=-0.06, P=.41), age and IOP(cc) (r=-0.02, P=.82), or age and IOP(G) (r=-0.11, P=.11).

Conclusions: Corneal biomechanical parameters are significantly decreased by aging without significant changes in central corneal thickness or IOP, suggesting that age-related structural changes resulting from collagen cross-linking may lead to a reduction of corneal biomechanical variables independent of central corneal thickness or IOP.