See: Secondary OAG caused by iatrogenic interventions and corticosteroid treatment (Sect. 6.2.3.1).

11.2Angle Closure Induced by Drugs

Some patient drug instructions do provide a warning: do not use or be careful if you have glaucoma! Most of instructions do not differentiate between open-angle and closed-angle diseases.

What drugs are potentially harmful in causing a change in the width of the chamber angle?

In anatomically predisposed eyes with a narrow, occludable chamber angle, a mid-wide pupil may induce a pupillary block followed by closure of the chamber angle. Also lens thickening, induced by drugs, may induce a pupillary block with acute or intermittent angle closure. Some drugs, such as cholinergic agents, thicken the ciliary body and induce an anterior movement of the iris and the ciliary body. Peripheral iridectomy is ineffective in such cases.

Dilation of the pupil (mydriasis) is induced by sympathomimetic (adrenergic) drugs which activate the musculus dilator pupillae, or by parasympatholytic (anticholinergic) drugs which block the musculus sphincter pupillae.

These drugs act on the adrenoreceptors (alpha, beta). They include the neurotransmitters adrenalins and noradrenaline. Phenylephrine eye drops in different concentrations (2.5%, 1.0%) are a powerful drug mainly used to examine the fundus. Phenylephrine or naphazoline are components of vasoconstrictors. These eye drops were produced to “whiten” a formerly red conjunctiva (due to vascular injection). Apraclonidine, administered locally after Nd:YAG iridotomy to lower the IOP, has a mild dilatory effect.

Epinephrine or adrenalin is used intravenously to treat several anaphylactic shocks or cardiac diseases. Asthma is treated with (beta-) adrenergic drugs applied by a spray or inhalator for bronchodilation.

11.2.2Indirect Sympathomimetic Drugs

These drugs increase the concentration of neurotransmitters in the synaptic cleft. Drugs causing mydriasis are amphetamines (also the synthetic ecstasy), cocaine and some antidepressants (noradrenaline reuptake inhibitors). Ephedrine is a constituent of many over-the-counter treatments for influenza and colds. It dilates the bronchi and constricts vessels (conjunctiva, nasal mucosa).