Damage from glaucoma is irreversible. Treatments focus on preventing further damage to the eyes. Patients should ask their ophthalmologist about the advantages, risks and side effects of treatment options.

Periodic (every three or four months) and thorough examination is crucial to the prevention of further eye damage and loss of vision. For patients who have already lost some of their vision, low-vision services may be an option to help them compensate and to help maintain remaining sight.

Medications used to treat glaucoma include:

• Eye drops. Prescription eye drops reduce intraocular pressure by decreasing the production of aqueous fluid or improving the flow of fluid through the drainage angle or other outflow areas. Eye drops, typically applied daily or several times a day, are a common and usually effective treatment for glaucoma and have been found to delay and even prevent the onset of glaucoma. The patient should follow instructions and not skip drops because damage to the optic nerves can occur if eye drops are not applied properly.
  
  
  Classes of eye drops include prostaglandins, adrenergics, miotics, beta blockers and carbonic anhydrase inhibitors. A physician can advise about possible side effects. Physicians may avoid prescribing certain types to people with diabetes. Beta blockers, a type of antihypertensive, can interfere with control of glucose (blood sugar) and may be a risk factor for secondary diabetes. The National Institutes of Health cautions that carbonic anhydrase inhibitors, a type of diuretic, may cause hyperglycemia and worsen kidney disease. It advises diabetic patients who are prescribed these drugs to be vigilant with glucose monitoring and report any problems to their physician.

• Oral medications and injections. Carbonic anhydrase inhibitors and a class of drugs called hyperosmotics can be taken by mouth and, for glaucoma emergencies, may be injected. Hyperosmotics, like carbonic anhydrase inhibitors, may be contraindicated for people with diabetes.

Researchers have found that some patients who respond poorly to one glaucoma medication may benefit from a combination therapy.

Some patients report relief from smoking marijuana. About a dozen U.S. states have laws supporting medical use of marijuana, but the federal government has banned it. According to the Food and Drug Administration (FDA), there is no scientific evidence for medical use of marijuana, but there is proof of harmful effects from smoking marijuana. Research into cannabinoids (marijuana-like medications, including extracts applied beneath the tongue) as a potential treatment for glaucoma, pain and other conditions continues.

Surgery is recommended if it is needed to prevent further optic nerve damage or if medication is ineffective or not tolerated by the patient. Possible complications of surgical procedures include infection, loss of vision, scarring, development of cataracts, swelling (edema), bleeding or undesired changes in eye pressure.

Surgery can be either laser (photocoagulation) or conventional:

• Argon laser trabeculoplasty. An outpatient laser procedure used to modify the trabecular meshwork (drain) to help control eye pressure by allowing fluid to drain from the eye. This procedure is used for open-angle glaucoma. First, numbing drops are applied to the eye.  Then several burns are made in the trabecular meshwork using a high-intensity beam of light aimed at the lens and reflected onto the meshwork. In this way the drainage space is enlarged and the eye pressure is reduced.
  
  This laser treatment is applied to one eye at a time and may take several weeks to treat the other eye. Also, it may be performed in two sessions per eye. According to the Glaucoma Research Foundation, it is 75 percent effective. The benefits of the procedure may be temporary and in some cases last only two years. Repeat procedures are usually ineffective. Glaucoma medication should still be taken after this procedure.
  
  There is a newer form of this procedure, selective laser trabeculoplasty (SLT), that uses a different laser and may cause less scarring and have better results. Recent research suggests that when trabeculoplasty needs to be repeated, SLT may produce better results than the argon procedure.

• Cyclophotocoagulation. A laser procedure used to destroy parts of the ciliary body to reduce its production of aqueous humor (fluid in the eye). This procedure is used in advanced or severe cases of glaucoma, in eyes with minimal or no vision, to reduce the eye pressure.
  
  
• Filtering microsurgery. An outpatient surgical procedure used to create a new drainage channel in the eye for the aqueous fluid to leave the eye. After the eye area is numbed, a small piece of tissue is removed to create a new area for the fluid to drain from. Types of filtering microsurgery include trabeculotomy in adult glaucoma and goniotomy in congenital glaucoma. The patient applies eye drops after surgery to prevent infection.
  
  This procedure is performed on one eye at a time and is scheduled four to six weeks apart for each eye. The success rate is 60 to 80 percent in lowering eye pressure, according to the National Eye Institute. A second operation may be required if the opening narrows from scarring. Possible side effects include infection, cataracts, bleeding or decreased visual acuity.
  
  
• Nonpenetrating surgery. Techniques developed as less-invasive potential alternatives to trabeculotomy in draining excess fluid. These include canalostomy, viscocanalostomy and deep sclerectomy.
  
  
• Drainage devices. A special plastic or collagen tube or shunt can be surgically implanted into the eye to absorb excess aqueous fluid and lower eye pressure. Such devices may be considered when other treatments have failed.
  
  
• Iridotomy. An outpatient procedure performed to stop a chronic or acute closed-angle attack of glaucoma. This is an emergency procedure performed by an ophthalmologist, who uses a combination of eye drops to constrict the pupil and provides the patient with medication to reduce the eye’s fluid production. Under anesthesia, a laser beam is used to create a small opening in the iris (colored part of the eye) to allow drainage of fluid through the trabecular meshwork. This may be done as a preventive measure for the unaffected eye as well. 

Some medications, including corticosteroids, vasoconstrictors (such as decongestants and antihistamines, including those in some eye drops), anticholingergics (e.g., bronchodilators, drugs for overactive bladder, drugs for Parkinson’s disease), antidepressants and anti-anxiety agents, have warnings for glaucoma patients. With some of these, precautions apply only for certain types of glaucoma. People who have or are at risk for glaucoma are advised to consult their ophthalmologist about which prescription medications, over-the-counter drugs and supplements they may safely use and which they should limit or avoid.