Effect of dorzolamide/timolol combination on the visual field in glaucoma

Primary Open-Angle Glaucoma Progression in Glaucoma Patients with Unchanged Topical Treatment over 3 Years - Retrospective Observational Cohort Analysis

BACKGROUND

Lowering intraocular pressure (IOP) is a mainstay of glaucoma therapy. It is, however, still an open question whether a comparable level of long-term IOP lowering achieved by different medications results in comparable protection for the retinal ganglion cells. The purpose of this study was to retrospectively analyze glaucoma damage progression in two cohorts of primary open-angle glaucoma patients with different and unchanged therapy over a period of 3 years, and the main objective of this study was to determine possible differences in terms of structural [retinal nerve fiber layer thickness (RNFL)] and functional [visual field (VF)] outcome.

PATIENTS AND METHODS

The retrospective observational cohort analysis compared two differently treated groups of glaucoma patients with their original, at study entry, topical therapy unchanged over 3 years. The main endpoint was the time course of RNFL thickness and VF mean defect (MD).

RESULTS

Twenty-one eyes were included in each group. The first group (21 eyes) was on a fixed combination of timolol and dorzolamide twice a day and the second group on one drop of prostaglandin analog, either latanoprost alone (15 eyes) or travoprost alone (6 eyes), in an unchanged regimen over a period of 3 years. IOP in mmHg at baseline and at 36 months was 11.9 ± 2.4 and 13.0 ± 2.1 in the first, and 12.9 ± 3.0 and 14.1 ± 3.2 in the second group, respectively. RNFL thickness values in micrometers were at baseline and at 36 months 77.8 ± 12.3 and 76.6 ± 15.2 in the first, and 77.5 ± 15.2 and 72.8 ± 14.5 in the second group, respectively. VF MD in dB were 1.7 ± 2.5 and 1.2 ± 2.9 in the first, and 0.9 ± 2.3 and 0.7 ± 2.6 in the second group, respectively.

CONCLUSION

Both groups had comparable baseline, as well as mean overall IOP. However, the course of IOP levels over time was different in the two groups, showing earlier and more pronounced long-term drift in the prostaglandin analog-treated group. RNFL thickness was comparable at baseline, however, RNFL thinning over time was more pronounced in the prostaglandin analog-treated group. There were no statistical differences between the groups in terms of VF MD at baseline and over time.

Roles of CYP2C19 Gene Polymorphisms in Susceptibility to POAG and Individual Differences in Drug Treatment Response

Background

The aim of this study was to investigate the roles of cytochrome P450 2C19 (CYP2C19) polymorphisms in primary open-angle glaucoma (POAG) susceptibility and individual responses to drug treatment.

Material/Methods

This case-control study consisted of 93 cases with POAG and 125 controls. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) was used to analyze CYP2C19 single-nucleotide polymorphisms (SNPs). After timolol treatment, patients were classified into side effect (SE) group and non-side effect (NSE) group. According to drug treatment responses, patients were divided into 3 groups: excellent group (Ex) (IOP ≥8 mm Hg); utility group (Ut) (5 <IOP ≤8 mm Hg), and ineffective group (In) (IOP ≤5 mm Hg). Data analysis was performed using SPSS software.

Results

We found no statistical differences in the alleles and genotypes frequencies of CYP2C19 between the case group and the control group (both P>0.05). Frequencies of extensive metabolizer phenotype and poor metabolizer phenotype or poor metabolizer phenotype and intermediate metabolizer phenotype were significantly different between the SE group and NSE group (both P<0.05). The distribution of intermediate metabolizer phenotype and extensive metabolizer phenotype were significantly different among Ex group, Ut group, and In group (all P<0.05).

Conclusions

We found no evidence that CYP2C19 polymorphisms are associated with susceptibility to POAG. However, different CYP2C19 metabolizer phenotypes were identified and observed to have important effects on the individual differences in drug treatment response.