There are a number of medicines available for lowering the IOP in glaucoma patients. Since this is a life-long treatment, it is important to select eyedrops that do not disrupt patient’s quality of life.
Frequently used eye drops and their respective possible side effects are:
Prostaglandin analogues
Latanoprost, Travoprost, Bimatoprost, Tafluprost
To be used as 1 drop- once a day at night. Of note, it can be used at daytime at the physician’s discretion.
Side effects: may cause redness of the eye (which may or may not resolve/fade in a few weeks), darkening of the color of iris (in light irides of mixed colors) and the skin surrounding the eyes, and it may cause fat reduction around the eye, leading to recession of the eyeball into the orbit. It can cause the eyelashes to grow darker and longer.
Beta-blockers
Timolol, Betaxolol, Levobunolol
Dose: one drop twice a day (like 7am – 7 pm). Some sustained release preparations are available that may be used only in a single morning dose.
Side Effects: Can worsen lung disease (like asthma, chronic obstructive airway disease), lower the blood pressure and heart rate, cause dizziness and insomnia and rarely depression, impotence and decrease libido. May inhibit symptoms of hypoglycemia in diabetics and alter the lipid profile.
Alpha adrenergic agonists
Brimonidine
Dose: To be used thrice a day if used alone and twice a day if combined with another glaucoma eye drop.
Side effects: may produce allergic reaction and itching in the eyes, and it may cause sleepiness and low blood pressure. It should be avoided in children (< 6 years) as it can cause excessive drowsiness and respiratory depression (breathing difficulty).
Carbonic anhydrase inhibitors
Brinzolamide ; Dorzolamide
Dose: To be used thrice a day if used alone and twice a day if combined with another glaucoma eye drop.
Side effects: Can cause stinging sensation in eyes and unpleasant taste in mouth. If IOP is very high, an oral medication (Acetazolamide) can also be given for a short time to control IOP, until the time laser or surgery is done.
Use of oral acetazolamide is associated with tingling, numbness, altered taste, indigestion, nausea, vomiting, skin rashes. Take food rich in potassium (orange juice, bananas, coconut water) to reduce side effects. In some cases, potassium tablets may be prescribed. Not to be used in patients with sickle cell disease (particularly for oral medication). As patients with sulfa allergy may get allergy from carbonic anhydrase inhibitors, please discuss this with your ophthalmologist.
Miotics
Pilocarpine represents this class of drugs. It works by increasing outflow. It was a very popular drug in the past, but has been replaced nowadays by new compounds due to its side effects profile. It is still used in some clinical situations, such as angle closure glaucoma or pre-laser treatment.
Possible side effects may include: ocular pain, headache, small pupil (miosis), blurred vision, and diminished vision in dim light situations.
Systemic side effects are rare and include increase salivation and sweating.
Fixed combinations
There are products that combine two drugs in one bottle. This is very useful for patients that need two drugs to control the disease. The existing combinations include:
- Timolol + pilocarpine.
- Timolol + carbonic anhidrase inhibitor (dorzolamide or brinzolamide).
- Timolol + brimonidine.
- Timolol + prostaglandine analog (latanoprost, travoprost or bimatoprost).
- Brinzolamide + brimonidine.
Fixed combinations are very popular, as many patients with glaucoma need at least two drugs to control the disease.
