BLOG: Systemic side effects of glaucoma drops

Glaucoma, the second leading cause of blindness worldwide, is a chronic and progressive disease that is traditionally treated by lowering IOP, often through the use of topical drops. While there are a range of medications available, they all have a varying degree of systemic side effects that are not always discussed. These side effects contribute to the well-documented compliance issues doctors and patients often face with topical drops. Eye drops typically used include prostaglandin analogs, alpha antagonists, carbonic anhydrase inhibitors and beta-blockers.

Prostaglandin analogs are the most common medications used as they are effective in lowering IOP. However, they may also cause conjunctival hyperemia, iris and eyelid pigmentation changes, and a deepening of the upper eyelid sulcus, which gives patients an appearance of ptosis. Alpha antagonists have fewer side effects but can adversely affect patients with hypertension, exacerbating their condition. Irregular pulse and tachycardia may also occur. I therefore avoid this medication with any patient who has a history of cardiac issues. Most patients do well with carbonic anhydrase inhibitors although they are contraindicated in anyone with a sulfa allergy or kidney stones.

Beta-blockers have a long list of possible side effects, including exercise intolerance — caused by adverse reactions in the circulatory and respiratory systems — and impotence in men. These are for any patients with asthma or breathing problems as these issues will be exacerbated. Even healthy patients and athletes may be unable to perform at their peak. Therefore, these are typically my last resort treatment.

Added to these possible side effects is the probable likelihood patients will develop dry eye, in great part due to the preservatives, such as benzalkonium chloride, which are in many of these medications. Many of my patients are elderly or postmenopausal women, populations that are commonly already battling dry eye. Adding drops with preservatives will only serve to further disrupt the tear surface.

Anything we can do to minimize dry eye issues and other possible side effects is desirable. Consequently, I typically use laser as my first-line treatment for glaucoma. MicroPulse laser therapy (MLT, Iridex) has shown impressive efficacy and safety profiles in numerous trials, and unlike topical therapies, it is not accompanied by a plethora of adverse side effects. MLT often results in a reduction of medications, further reducing patient burden and the chance of side effects.

Reference:

Quigley HA, et al. Br J Ophthalmol. 2006;doi:10.1136/bjo.2005.081224.

Disclosure: Toyos reports she is a speaker and consultant for Valeant and Sun; conducts research for Lumenis, Magellan and Kala; is a speaker and consultant and does research for Shire, Mallinckrodt and MixtoLasering; is a consultant and does research for DigiSight; does research for Novaliq; and is a consultant for Iridex.