Purpose: In managing glaucoma through the lowering of intraocular pressure (IOP), beta-blockers (e.g. timolol) are commonly the drug of first choice, with other drugs added to control IOP such as carbonic anhydrase inhibitors (e.g. dorzolamide). The present survey was instigated to assess the COSOPT (fixed combination of topical timolol and topical dorzolamide) prescription behaviour of Swiss office-based ophthalmologists and to evaluate the IOP-lowering efficacy of COSOPT under real-life private practice conditions.

Methods: A survey was conducted in Swiss ophthalmologist practices. Ophthalmologists were asked to report their experience with COSOPT therapy prescribed to patients with glaucoma or ocular hypertension. Parameters recorded were: patient demographics, IOP, reason for choosing COSOPT, continuation of COSOPT therapy after completion of the survey and, if stopped, reason for discontinuation, and spontaneously occurring side-effects. All entries were optional. Since the purpose of this survey was to obtain a realistic picture of daily practice in Swiss ophthalmologists' offices, no guidelines with regard to measurement of IOP, time between visits and actual treatment were given.

Results: Data of 733 patients were included in this analysis. COSOPT as sole therapy was prescribed to 538 patients (74%), whereas 120 (16%) were put on a combination regimen of COSOPT + latanoprost. The remaining 75 patients (10%) received combinations of COSOPT with other ocular hypotensives. When assessing those patients put on COSOPT alone, IOP reduction in new, previously untreated patients was 10.8mmHg (average), 5.4mmHg (average) in upgrades from previous monotherapy and 2.7mmHg after switch from free combination therapy. Patients treated with a combination of COSOPT + latanoprost showed an IOP reduction of 27mmHg (new, previously untreated patients), 7.6mmHg (upgrades from monotherapy) and 3.8mmHg (switches from previous free combination regimen). Therapy was continued in 89% of all patients overall and in 91% of new patients treated with COSOPT alone (first line). 6.8% stopped therapy due to side-effects.

Conclusions: COSOPT, the fixed combination of 0.5% timolol and 2% dorzolamide, is broadly prescribed to new, upgrade and switch patients in Switzerland. COSOPT therapy is well-tolerated and highly efficacious for patients requiring strong IOP lowering. Nine out ten patients stay on therapy after 1-2 months of treatment.