Glaucoma Medication Side Effects & Contraindications
By: Paul M. Karpecki, OD, FAAO
Clinical Director – PECAA
Glaucoma affects millions of patients and is a very important part of optometry practice. We know there are inherent risks with almost all pharmaceutical agents and glaucoma medications are no exception. Having been an expert witness in a number of malpractice cases and most recently one involving glaucoma medications, makes me realize that a quick reminder of these contraindications (and side effects) is valuable.
There are no absolute contraindications for this class except patients with a known hypersensitivity to the ingredients. However a relative contraindication would include patients with ocular inflammatory conditions such as uveitis, CME or chronic inflammatory eye disease. Another might be unilateral treatment because of the ocular side effects and there are times when unilateral glaucoma may develop such as in the cause of trauma with iris recession or post HZO or HSV uveitis. Ocular side effects include iris and sometimes periorbital skin pigmentation changes, eyelash growth, hyperemia, and orbital fat loss. Some patients may also experience burning and stinging with these drops.
Contraindications to this class are generally patients with pulmonary or heart disease. This class of drugs can cause bradycardia or a lowered heart rate, lower blood pressure and can induce arrhythmia in susceptible patients. There are even reports that beta-blockers can raise serum triglyceride levels. They can also cause bronchial constriction, adversely affecting patients with asthma or COPD for example. They can cause sexual dysfunction, reduced libido, general weakness, depression and other central nervous system (CNS) side effects as well. Because the use of beta blockers has increased as a second choice medication mainly via combination agents, we must educate patients about these side effects.
Selective Alpha Agonists:
Although this class is generally well tolerated, there is a high incidence of allergy to certain brands within the class and many experts advise against the use of this class in children because of the potential CNS side effects. By stimulating alpha-2 receptors of the CNS, there is the potential for orthostatic hypotension, low blood pressure, fatigue, headache, drowsiness and dry mouth.
Carbonic Anyhdrase Inhibitors:
In this class we use both the topical and the oral forms (e.g. use or oral diamox in acute angle closure cases) and contraindications/side effects can vary between the two. For the topical form, there are few if any contraindications. There is a rare risk of allergic cross-sensitivity in patients with significant sulfonamide allergies that should be ascertained. Side effects include burning, stinging and eye discomfort. In the oral form however, contraindications include patients with advanced kidney disease or a history of severe sulfonamide allergy. Reports of sickle cell crisis have also been reported in oral CAI use. Side effects range from metabolic acidosis and kidney stone formation to paresthesia (tingling or ‘pins and needles’ in the hands and feet), dysgeusia (change or distortion of taste), GI upset, memory problems, depression and dehydration.
Certainly the side effects general pale in comparison to the risk of blindness but the list may help you select more appropriate medications for each patient and perhaps increase drug compliance. Contraindications should be heeded however as they range from morbidity conditions to progression of disease and even potential death. A whole new set of topical glaucoma drugs and drug delivery-system treatments are set to reach US FDA approval in the next 12-18 months. These will be a welcome addition as they seem to address new mechanisms of action or have results that exceed existing medications. They may also have a lot less systemic disease effects, which could make them ideal primary or additional therapy treatments. We’ll discuss the glaucoma pipeline in a near future PECAA e-newsletter.