Glaucoma is one of the leading causes of blindness, and when it damages the optic nerve, the damage is irreversible. However, the good news is that the progression of glaucoma can be halted if it is caught in its early stages. Here are some of the latest treatments for glaucoma.
The two main types of the disease are open-angle and closed angle. Open-angle comes on gradually, with the patient not even noticing they are losing their vision. Closed-angle glaucoma strikes suddenly, is excruciatingly painful, and is considered a medical emergency.
Most people who have open-angle glaucoma are given eye drops to lower the pressure in their eye that leads to optic nerve damage. One type of medication works by allowing more aqueous fluid to drain out of the patient’s eye, while another lowers the level of aqueous fluid that the eye produces. Some ophthalmologist give patients more than one type of eye drop. Types that lower the production of fluid include:
• Levobunolol
• Timolol
• Metipranolol
• Carteolol
These drugs are known as beta blockers.
Patients apply these drops once or twice a day, and they’ve been shown to work well. But because they block chemicals in the body that resemble adrenaline, their side effects can result in a slow heart rate, fatigue, and low blood pressure. Newer drugs such as betaxolol have fewer side effects.
Drugs called carbonic anhydrase inhibitors also lower how much fluid is in the eye. In the form of eye drops, these medications have to be used as often as three times a day. They can be taken in pill form, but this is rare. Because they decrease the production of many types of fluids in the body, they can only be used for a short time. Types of carbonic anhydrase inhibitors are dorzolamide, acetazolamide, and brinzolamide.
Other drugs both reduce the amount of aqueous fluid and allow it to drain. They include brimonidine and dipivefrin. Some patients are allergic to these drugs.
Some drugs that allow the fluid to drain from the eye resemble prostaglandins, which are chemicals that act very much like hormones in the body. These drugs include:
• Travoprost
• Latanoprost
• Bimatoprost
• Tafluprost
Miotics encourage the eye to drain by causing the patient’s pupil to constrict. They are seldom used now because of side effects which can include headache, blurry vision and a permanently constricted pupil. They also put the patient at increased risk for a detached retina. One type of this drug is used by patients who have closed-angle glaucoma.
Eyedrops can cost a patient about $1700 a year.
Drugs called osmotic agents are given to patients who have sudden attacks of glaucoma and whose eye pressure stays high in spite of other drugs or treatments. One drug called isosorbide is taken orally and another, mannitol, is given intravenously. The side effects of these drugs can be severe, including brain bleeding. They can’t be taken by people with heart disease, uncontrolled diabetes, or problems with their liver or kidneys.
In Europe, eye surgery is the treatment of choice for glaucoma patients. It is performed on people with both open and closed angle glaucoma. The most popular surgery for glaucoma is called trabeculectomy. In this surgery, the ophthalmologist removes a bit of the trabecular meshwork to create a new drainage canal for the eye. They also create a tiny filtering bleb out of a piece of the conjunctiva, which is the clear membrane over the white of the eye. Aqueous fluid enters this bleb and is absorbed by the body. Trabeculectomy has proven to be a very effective surgery.
Laser iridotomy is used for people with closed-angle glaucoma. During this procedure, the surgeon makes a tiny hole in the iris to let the aqueous fluid drain. A procedure called trabeculoplasty is performed on people with open-angle glaucoma. A patient can opt for argon laser trabeculoplasty or selective laser trabeculoplasty. Both lasers create tiny burns in the trabecular network in the eye to make drainage easier. Trabeculoplasty is done for people who are already using eye drops and is not a permanent solution. Many patients have to return for further treatments, especially with selective laser trabeculoplasty.
Other laser treatments either burn or freeze the ciliary bodies that create the aqueous humor. The former is called laser cyclo-ablation, while the latter is cyclocryopexy.
The cost of treatment depends on whether it is done in an ambulatory clinic or in a hospital. Laser treatment may cost about $1300 in a clinic and $4900 in a hospital.
Intraocular implants are also used to treat glaucoma. In this surgery, the ophthalmologist attaches tiny tubes to a reservoir beneath the conjunctiva. Aqueous humor flows through the tubes and collects in the reservoir. Some patients choose this operation instead of a trabeculectomy. Sometimes it is done without a reservoir to guard against the ocular pressure becoming too low. In that case, the surgeon implants tiny shunts.
Clinical trials are ongoing for new and improved ways to treat glaucoma, whether it is new drugs such as Rho-kinase inhibitors or new, minimally invasive techniques such as the InnFocus Micro-shunt, the Trabectome or the Xen glaucoma implant.
