Fluoxetine oral administration increases intraocular pressure.

CORRESPONDENCE Fluoxetine oral administration increases intraocular pressure EDITOR,-Fluoxetine is a widely prescribed antidepressant which acts as a selective inhibi-tor of neuronal serotonin uptake.' Recently, Ahmad2 reported on a case of acute narrow angle glaucoma due to fluoxetine administration. For this purpose, we verified the intraocular pressure (IOP) variations in 20 consecutive depressed outpatients (five males and 15 females, age range 33-47 years) to whom fluoxetine therapy was first prescribed. All patients received a complete ophthalmic examination to exclude the pre-existence of both acute and chronic glaucoma. Patients with systemic diseases other than affective disorders were excluded from the study. After at least 12 hours of fasting, in early morning (8 am) subjects were assigned to either 20 mg of oral fluoxetine or placebo in a randomised crossover double blind fashion. The alternative treatment was given 1 week later, a time lag considered sufficient for a single dose fluoxetine washout.3 Intraocular pressure was recorded (with a Goldmann tonometer mounted on a Haag-Streit slit-lamp) at baseline and hourly up to 12 hours, both when patients were given fluoxetine and when they were given placebo. All patients showed a significant increase in IOP 2 hours after oral administration of fluox-etine and 8 hours later some patients still exhibited higher IOP values (Fig 1); however, when patients received placebo there were no significant changes in IOP. Figure 1 Intraocular pressure variations after fluoxetine and placebo oral administration.All values are mean plus or minus SD. Paired Student's t test was usedfor statistical analysis. *p<O. 05; **p<O. 01 (treated versus untreated). The mechanism by which fluoxetine increases IOP might be due to the inhibitory effect on serotonin uptake. In fact serotonin, when injected into the anterior chamber, produces a significant increase in IOP4 and ketanserin, an agent with serotonergic blocking properties, reduces IOP both in animals and in humans.5 These data suggest that oph-thalmic examination might be included in the protocol of depressed patients given fluoxetine therapy because this drug might raise in-traocular pressure. new selective inhibitor of uptake of serotonin into synaptosomes of rat brain: 3-(p-trifluoromethy-phenoxy)-N-methyl 3-phenyl-propylamine. EDrroR,-I welcome Williamson et al's recent article' and your editorial2 suggesting that school vision screening may be the optimum method of detecting amblyopia in children in some circumstances. I would support the view that a larger number of children could be screened. In Glasgow, in the north west area, covering approximately the same geographical area as that quoted …