The effect on intraocular pressure of latanoprost once or four times daily

Aims-To compare the effect on intraocular pressure (IOP) of latanoprost app lied once daily with four times daily and to study if the difference persis ted when treatment changed to once daily. Methods-IOP was followed in 28 healthy volunteers in a double masked random ised 52 day study. Latanoprost 50 mug/ml was administered once daily in one eye and four times daily in the other during 2 weeks. Subsequently both ey es received one daily drop for 2 weeks. After another 3 weeks without treat ment, a single drop was instilled in each eye. Results-The IOP reduction on days 2 and 3 was greater in the eyes treated w ith four daily doses (p <0.01). During the following period there were no s tatistically significant differences between the eyes. After 3 weeks withou t treatment the IOP was lower than pretreatment (p <0.001). A single dose o f latanoprost on day 50 resulted in a similar decrease in IOP in both eyes. Transient photophobia, mild flare, and/or a few cells occurred in 15 subje cts. Two subjects were withdrawn because of photophobia and/or signs of ant erior uveitis. Conclusion-Latanoprost four times daily caused an IOP reducing effect which was similar to once daily dosing, except for the first 2 days of treatment when it was more effective. Transient photophobia, cells' and flare were c ommon during the four dose regimen, but resolved spontaneously without cess ation of treatment.