SSRIs and intraocular pressure modifications. Evidence, therapeutic implications and possible mechanisms

SSRIs are the most commonly prescribed antidepressant drugs, in part because of their favourable safety profile compared with older antidepressants. However, the widespread use of SSRIs leads to an increased occurrence of rare adverse effects. This review, based on data from published experimental research, clinical studies and case reports, describes the role of serotonin in the control of intraocular pressure (IOP) and the evidence for IOP modifications in patients receiving SSRIs. In a small percentage of patients with depression, the cause of SSRI withdrawal has been the occurrence of ill-defined visual disturbances. It can be speculated that in some of these patients, the iatrogenic ocular alterations could have been due to changes in IOP. There have also been a limited number of cases reports of glaucoma occurring during treatment with SSRIs, although causality is hard to establish. Nevertheless, in a small clinical study assessing the effect of a single dose of fluoxetine on IOP, the drug was shown to increase this parameter, although the effect was asymptomatic. The clinical signs of unexpected adverse drug effects are often disregarded, with the exception of those characterised by serious symptoms (such as acute angle-closure glaucoma in the case of IOP modifications). Also, the distribution of iridocorneal angle configurations in the general population implies that an adverse effect on IOP will be pauci- or asymptomatic in most patients (intermittent, sub-acute or progressive angle-closure glaucoma). As a result, it is likely that the incidence of SSRI-related IOP modifications is underestimated. Until the involvement of SSRIs in IOP modifications is better understood, ophthalmological consultations should be considered before starting and during treatment with any SSRI in patients with glaucomatous risk factors, especially those who are elderly.