Abstract
Purpose:
Corneal hysteresis (CH) is a measure of corneal viscous dampening and studies have found an association between CH and progressive visual field worsening in primary open angle glaucoma (POAG). Additionally, associations have been reported between intraocular pressure (IOP) reduction and changes in CH as well as between cataract extraction (CE) and IOP reduction. This study seeks to investigate the relationship between post-CE IOP reduction and changes in CH among patients without glaucoma.
Methods:
We retrospectively analyzed charts from 230 consecutive patients undergoing phacoemulsification CE with posterior chamber intraocular lens implantation in a private practice in New York City. All included patients underwent pre- and post-operative measurements with the Ocular Response Analyzer (Reichert) at 2-4 months and at 10-12 months following surgery. Data collected included age, CH, central corneal thickness, corneal resistance factor, and IOP.
Results:
65 patients met inclusion criteria. The mean age of patients was 71.2 ± 8.3 years. Average pre-operative, 2-month and 12-month post-operative IOP values were 14.8 ± 3.4, 12.1 ± 3.0 and 12.6 ± 3.0 mmHg respectively (p<0.05 for comparisons to pre-operative IOP). CH measurements at each time period were 10.1 ± 1.8, 9.9 ± 1.8 (p=0.9 for comparison to pre-operative CH) and 10.3 ± 1.6 mm Hg (p=0.2 for comparison to pre-operative CH). Preoperative CH was not predictive of IOP reduction at 2 months post-operatively (β = -0.2 [95% CI -0.8, 0.4], p=0.5). However, preoperative CH was found to be a statistically significant predictor of magnitude of IOP reduction at 12 months following CE when controlling for patient age (β = -0.4 [95% CI -0.8, -0.1], p=0.03).
Conclusions:
This is the first study to confirm what has previously been shown with medical and a laser-based intraocular pressure reduction: that a lower corneal hysteresis is associated with a larger magnitude of intraocular pressure reduction.
Keywords: 479 cornea: clinical science •
568 intraocular pressure •
743 treatment outcomes of cataract surgery