Selective serotonin reuptake inhibitors: a review of its effects on intraocular pressure

Abstract

The increase in serotonin (5-HT) neurotransmission is considered to be one of the most efficacious medical approach to depression and its related disorders. The selective serotonin reuptake inhibitors (SSRIs) represent the most widely antidepressive drugs utilized in the medical treatment of depressed patients. Currently available SSRIs include fluoxetine, sertraline, paroxetine, fluvoxamine, citalopram and escitalopram. The primary SSRIs pharmacological action's mechanism consists in the presynaptic inhibition on the serotonin reuptake, with an increased availability of this amine into the synaptic cleft. Serotonin produces its effects as a consequence of interactions with appropriate receptors. Seven distinct families of 5-HT receptors have been identified (5-HT(1) to 5-HT(7)), and subpopulations have been described for several of these. The interaction between serotonin and post-synaptic receptors mediates a wide range of functions. The SSRIs have a very favorable safety profile, although clinical signs of several unexpected pathologic events are often misdiagnosed, in particular, those regarding the eye. In all cases reported in the literature the angle-closure glaucoma represents the most important SSRIs-related ocular adverse event. Thus, it is not quite hazardous to hypothesize that also the other reported and unspecified visual disturbances could be attributed - at least in some cases - to IOP modifications. The knowledge of SSRIs individual tolerability, angle-closure predisposition and critical IOP could be important goals able to avoid further and more dangerous ocular side effects.

Keywords: Fluoxetine; citalopram; escitalopram; fluvoxamine; intraocular pressure; paroxetine; sertraline; side effects..

Fig. (1)

The biosynthesis of serotonin from the amino acid tryptophan.

Fig. (2)

The catabolism of serotonin.

Fig. (3)

Schematic horizontal section of the human eye: anatomic structures and vasculature. Legend: a, cornea; b, iris; c, lens; d; suspensory ligament of the lens (ciliary zonule of Zinn); e, ora serrata; f, medial rectus muscle of the eye; g, retina; h, sclera; i, choroid; l, optic nerve head; m, central fovea of the macula; n, lamina cribrosa; o, irido-corneal angle. 1, minor circle of iris; 2, Schlemm's channel; 3, major circle of iris; 4, iuxtalimbic conjunctival vessels; ciliary circle; 6, anterior ciliary artery; 7, anterior ciliary arteries and veins; 8, vorticose vein; 9, retinal microvasculature; 10, episcleral arteries and veins; 11, long posterior ciliary artery; 12, short posterior ciliary arteries; 13, central retinal artery and vein; 14, perioptic nerve arteriolar anastomoses (circle of Haller and Zinn); 15, pial microarterioles.

Fig. (4)

Schematic horizontal section of the anterior segment of the human eye.