Abstract
Purpose:
To determine whether the use of topical prostaglandin analogs (PGAs) affects the biomechanical properties of the cornea based on the integrated analysis of the Reichert Ocular Response Analyzer (ORA), Goldmann tonometry and ultrasound pachymetry.
Methods:
Seventy eyes of 35 patients, aged 40-85 years with open angle glaucoma and/or intraocular hypertension treated with topical PGAs were examined. Only refraction between -6.00D and +6.00D were included. Exclusion criteria: patients with any corneal disease, such as Fuchs corneal endothelial dystrophy, keratoconus or history of corneal trauma or surgery, as well as contact lens wear. Patients with stable glaucoma parameters and topical PGAs in both eyes were asked to discontinue the PGAs in the best eye (less damage on VF - better MD or lower max IOP if MD equal). The measurements were taken before PGAs cessation and repeated 6 weeks after cessation. Patients then restarted PGAs and measurements were repeated once more after 6 weeks. All measurements were performed by the same trained technician, with the same equipment and at the same time of day. The contralateral eye served as control eye in the statistical analyses. Goldmann tonometry was used to measure IOP, ultrasound pachymetry for CCT, and ORA for the biomechanical properties, including corneal hysteresis (CH). The hypothesis of no effect of discontinuation of PGAs on the biomechanical properties was examined by OLS regression with control for clustering within patients by Stata 12.1.
Results:
A statistically significant change in corneal hysteresis of study eye was found between visit 1 (on PGA) & visit 2 (no PGA): CH increased by 1.07 with 95% CI (0.55; 1.59), with CH values of 8.97 (±1.62, p=0.05) & 10.00 (± 1.47, p=0.05), visit 1 & 2 respectively. As well, between visit 2 (no PGA) & visit 3 (PGA restarted): CH decreased by 0.47 with 95% CI (-1.22; 0.29), with CH values of 9.30 (±1.47, p=0.05) on visit 3. There was also a statistical difference between the study and control eyes on visit 2 (t=-2.29; p=0.03) and no statistical change between the study and control eyes on visit 1 & 3 (t=1.48; p=0.15) & (t=-1.04; p=0.33).
Conclusions:
The topical prostaglandin medication affects the biomedical properties of the cornea and reduces corneal hysteresis. These changes should be taken into account when evaluating IOP lowering response to PGA medications.
Keywords: 503 drug toxicity/drug effects •
479 cornea: clinical science