Purpose: To examine if different dose regimens of latanoprost cause a difference in daytime intraocular pressure (IOP) in normal eyes and if such changes could be attributed to an increase in aqueous flow.
Methods: In a randomised, open, cross-over study latanoprost 50 microg/ml was instilled in one eye of 18 volunteers. Three dose regimens (one/three drops once daily or one drop twice daily) were evaluated. IOP was measured at the end of each 14-day treatment period. Aqueous flow and endothelial permeability were assessed by fluorophotometry.
Results: All dose regimens reduced IOP significantly (p < 0.001). Once daily applications reduced IOP more than twice daily (p < 0.01). No statistically significant difference in aqueous flow was detected between different treatments. One drop daily increased aqueous flow compared with control eyes (p < 0.05). A similar, but not statistically significant tendency was present with the other regimens. Corneal endothelial permeability was not affected.
Conclusion: Once daily applications of latanoprost reduce IOP more effectively than twice daily in normal subjects. This cannot be explained by an increase in aqueous flow.