Abstract
Abstract: :
Aim: To determine if prostaglandin analogues (PA) have any effect on the cornea thereby influencing intraocular pressure (IOP). Methods: Prospective, randomised study in which criteria for inclusion was – all glaucoma patients above 15 years, those that were not already on a PA and whose glaucoma control required the commencement or addition of a topical medication. Contra lateral eye not requiring PA was included as control. The IOP of each eye was measured by Goldmann aplanation tonometry (GAT). The IOP, corneal hysteresis (CH) and excess ocular pressure (EOP) was measured by the Ocular Response Analyser (ORA) non–contact tonometer with corneal response (NCTCR) (Reichert Ophthalmic Instruments, Buffalo, NY). These measurements were done at baseline, one month and two months. In addition corneal pachymetry (CCT) was performed by Nidek ultrasound pachymeter at baseline and two months. Paired student t–test SPSS version 11.5 was used for statistical analysis. Results: The study included 74 eyes of 44 patients; of these there were 41 right and 33 left eyes. 54.5% of patients (n=24) were Caucasians, 22.7% (n=10) were black and 22.8% (n=10) were Asians. 14 patients were included as control. The mean baseline GAT was 21.27 mmHg (SD 6.65). GAT at one month was 15.3 mmHg, (SD 3.36) and at two months 16.39 mmHg, (SD 5.29). Corneal thickness was found to be significantly reduced at two months (mean 533.87, SD 39.68) following baseline (mean 542.02, SD 41.57) for the PA group (p<0.001), whereas corresponding values for controls was not significant (baseline 560.31, SD 46.33, and at two months 553.31, SD 51.23), p=0.071. Corneal hysteresis was significantly different for the PA group at one month (4.29, SD 1.63) and at two months (4.65, SD 2.38) when compared to baseline (5.29, SD 2.0) (p<0.001 and p=0.006). Control subjects showed no difference (baseline 5.07, SD 1.45; one month 5.76, SD 1.94; two months 5.23, SD 2.1), (p=0.084 and p=0.627 respectively). Conclusions: Prostaglandin analogues appear to cause thinning of the cornea and an increase in corneal hysteresis after two months of use.
Keywords: intraocular pressure • cornea: clinical science • clinical (human) or epidemiologic studies: systems/equipment/techniques