A Comparison of Dorzolamide and Timolol in Patients with Pseudoexfoliation and Glaucoma or Ocular Hypertension

Purpose: The purpose of the study is to compare the efficacy and safety profile of 2.0% dorzolamide (three times daily) and 0.5% timolol (twice daily) for up to 6 months in patients with glaucoma or ocular hypertension associated with pseudoexfoliation. The additive effects of dorzolamide and timolol in patients requiring add-on therapy also was evaluated.

Methods: This was a double-masked, randomized, parallel comparison study at 15 Scandinavian sites. One hundred eighty-four patients with pseudoexfoliation and either glaucoma or ocular hypertension who were 21 to 85 years of age were studied. The treatment groups were 2.0% dorzolamide three times daily and 0.5% timolol maleate twice daily.

Results: At 6 months, the mean percent reduction in intraocular pressure of 2% dorzolamide and 0.5% timolol was 24% and 29%, respectively, at morning peak and 21% and 23%, respectively, at afternoon trough. The additional intraocular pressure-lowering effect of adding 2.0% dorzolamide twice daily to patients receiving timolol was 14% and 15%, at peak and trough, respectively. There were no differences between treatment groups in the incidence of clinical adverse experiences, and dorzolamide was not associated with the systemic adverse effects typically ascribed to the use of oral carbonic anhydrase inhibitors.

Conclusion: Two percent dorzolamide (three times daily) was effective and well tolerated in patients with glaucoma or ocular hypertension associated with pseudoexfoliation over the course of 6 months; 0.5% timolol (twice daily) had a greater level of intraocular pressure-lowering activity than did dorzolamide, although the difference between the two treatments became less pronounced during the study period. Finally, 2.0% dorzolamide (twice daily) produced additional lowering of intraocular pressure when given with 0.5% timolol (twice daily).