The aim of this study was to assess corneal hysteresis (CH) and corneal resistance factor (CRF) in healthy subjects, to evaluate the relationship with age, and to investigate possible associations with other ocular factors.
Four hundred Italian subjects (male-to-female ratio, 168:232; mean age, 58.8 ± 17.2 years) were included and divided into 5 subgroups based on age. CH, CRF, and central corneal thickness (CCT) were measured by using the Ocular Response Analyzer and the integrated handheld pachymeter, and their relationship with gender, age, and ocular factors was evaluated.
The mean CH, CRF, and CCT values were 10 ± 1.6 mm Hg, 10.5 ± 1.7 mm Hg, and 532.2 μm, respectively. Women had a lower mean CH (9.9 vs. 10.2 mm Hg; P = 0.04) and CRF (10.3 vs. 10.8 mm Hg; P = 0.03) than did men. The youngest subjects had the highest CH (11.2 ± 1.5 mm Hg), whereas the oldest patients had the lowest CH values (9 ± 1.1 mm Hg). No significant differences in CRF were observed between age groups. CH and CRF showed a positive correlation (r = 0.58; P < 0.001), and both had a positive association with CCT (r = 0.27; P < 0.001 and r = 0.57; P < 0.001, respectively). The strongest correlations were observed between Goldmann-correlated intraocular pressure (IOP) and corneal-compensated IOP (r = 0.68; P < 0.001) and between Goldmann-correlated IOP and Goldmann applanation tonometry (r = 0.88; P < 0.001).
Gender and advancing age may influence corneal biomechanical properties. In our population, CH decreased with aging, and men demonstrated a higher CH and CRF than women did. Further, CH, CRF, and CCT were significantly related.