Glaucoma is a disease of the optic nerve which is responsible for transmitting information from the eyes to the brain. An increase in the pressure of the eyes, called intraocular pressure or IOP, can cause damage to the optic nerve leading to glaucoma. Treatment of glaucoma aims at preserving vision, usually by lowering eye pressure. In fact, glaucoma eye drops are usually the first choice of treatment. Glaucoma lasers and surgery are other treatment options available.
In case your glaucoma doctor thinks you are a suitable candidate for medical management, she will prescribe one or more glaucoma eye drops for you. If you want to know more about complementary and alternate medication for glaucoma, read here.
You may want to read if you are at risk for glaucoma, and about glaucoma symptoms.
Types of Glaucoma Eye Drops
Glaucoma eye drops are of several types. Each type has general characteristics typical to the group, with some variations between individual drugs. Your doctor may prescribe the branded or generic version of the medication depending on personal preference and hospital policy.
Sometimes, one drop may not be sufficient to preserve your vision. That is, if the target IOP is not achieved with one drug, your doctor will add on one more medicine. The doctor may also prescribe a fixed dose combination. In this, there are two drugs in one bottle, which helps make your glaucoma eye drops easier to remember. This also decreases the preservatives you instill in your eye, and so, are preferred over separate bottles.
Mechanism of action of glaucoma eye drops
All glaucoma medications act by decreasing the eye pressure. There are two ways of decreasing the pressure inside the eye. One, decrease the the production of aqueous humor, which is the fluid inside the eye. Two, increase the outflow or drainage of this fluid inside the eye.
Beta blockers and carbonic anhydrase inhibitors decrease the production of aqueous. Prostaglandins and parasympathomimetics increase the outflow of the aqueous. Alpha adrenergics decrease IOP by both, increasing outflow and decreasing production of the fluid inside the eye.
Your doctor will pay special attention to the mechanism of action of drugs when prescribing a fixed dose combination. She will invariably choose two drugs which have a different mechanism of action so you get the maximum benefit fro your glaucoma eye drops.
Prostaglandins
These glaucoma eye drops are used only once a day, which makes them easy to remember. In addition, they provide the best IOP control for twenty four hours. This is why prostaglandins are the first line treatment for glaucoma. They are available as fixed dose combination with beta blockers.
Side effects
They do not have many known systemic side effects which makes them safe for use. Local side effects include change in color of eyes (especially for blue and green eyes), lengthening of eyelashes, as well as a burning sensation and redness of eyes. They may also increase inflammation inside the eye.
Names of drugs
The drugs in this class include Latanoprost, Bimatoprost, Travoprost and Unoprostone. The branded versions of these drugs are called Xalatan (Pfizer), Lumigan (Allergan), Travatan (Alcon) and Rescula (Novartis).
Beta-blockers.
Beta blockers were the most prescribed glaucoma eye drops worldwide. With the introduction of prostaglandins their popularity has decreased, mainly because of their systemic side effects and twice daily dosage. They, however, continue to remain the most popular add-on eye drop for glaucoma. They are available as fixed dose combination with prostaglandins, alpha agonists and carbonic anhydrase inhibitors.
Side effects
These eye drops may decrease heart rate, and increase your breathlessness, especially if you have asthma. In addition, it can also cause depression and derange your blood lipids. Therefore, there use requires special precautions. This is why your eye doctor will ask you in detail about any existing heart disease, hypertension, diabetes and asthma before prescribing these glaucoma eye drops.
Names of drugs
Common beta blockers in current practice include Timolol, Betoxolol. The branded versions are called Timoptic XE (Merck), and Betoptic S (Alcon) respectively. Others include carteolol, levobunolol, and metipranolol.
Alpha-adrenergic agonists.
These drugs are either prescribed twice or thrice a day. Alpha agonists are also prescribed as an adjunct to first line glaucoma eye drops, or in case the latter are contraindicated. They are available as fixed dose combination with beta blockers, and with carbonic anhydrase inhibitors.
Side effects
These drugs may also cause adverse reactions. Side effects include redness of eyes, eye allergies, and dilated pupils.
Names of drugs
Brimonidine and apraclonidine are the glaucoma eye drops in this class. Iopidine (Alcon), and Alphagan (Allergan) respectively, are the branded versions of the drugs.
Carbonic anhydrase inhibitors
These glaucoma drugs can actually be prescribed as oral pills and eye drops. We will only discuss the eye drops in this section. They are also important add on glaucoma eye drops. They are available as fixed dose combination with beta blockers, as well as with alpha agonists.
Side effects
Common side effects include burning and redness of eyes, and a metallic or bitter taste in the mouth.
Names of drugs
The important glaucoma eye drops in this class are dorzolamide and brinzolamide. Trusopt (Merck) and Azopt (Alcon) respectively are the branded versions.
Parasympathomimetics
Current glaucoma practice does use these drops very often. However, parasympathomimetics have proven to be a boon in the management of angle closure glaucoma.
Side effects
Common side effects parasympathomimetics are brow ache, pupil constriction, burning, and reduced night vision.
Names of drugs
The commonly used glaucoma eye drop in this class is pilocarpine. Carbachol, echothiophate and demecarium are the other glaucoma eye drops.
