Glaucoma surgery

Until recently, few eye doctors would recommend glaucoma surgery as initial treatment. The general principle of such surgery is to let aqueous humor leak out of the eye through a hole created at the junction of the colored and white part (where the iris meets the sclera) under the covering layer called the conjunctiva. The chief reason to avoid surgery was pretty obvious and often expressed in plain English by patients: “you can’t go blind from eye drops, but you can with surgery”. As surgery complications decreased over the years, and as we recognized that patients preferred the idea of eye drops, but didn’t take them at an ideal rate, some argued that surgery first had a strong argument in its favor.

A large controlled study (the Collaborative Initial Glaucoma Treatment Study) then randomly assigned volunteer, new open angle glaucoma patients to take either eye drops or have trabeculectomy glaucoma surgery (see section Operations for glaucoma). Ten years into the study, both groups were doing well, and those who got surgery in both eyes were, if anything doing slightly better at preserving their visual field test results. Indeed, as shown in other studies, one can get the eye pressure to fall really low with trabeculectomy. But, 20% of operations had failed to keep pressure down well enough (in the study surgery was repeated and was often successful for longer). And, as with drops and laser, a small percentage of early successes lose pressure control every year that we follow the patient.

The risks of surgery can be generally grouped into the bothersome and the dangerous. Among the former, patients who have the surgery have a minor gritty sensation off and on. Most often this gets better quickly. For 1-2% of patients, the feeling in the surgical area is too troublesome and revision surgery is done to relieve it. More serious problems include developing so low an eye pressure that vision is poor, requiring revision surgery to raise pressure. Infections happen early after surgery in one per 5,000 eyes, and over time, there is a continued chance that the area of surgery makes the eye more susceptible to later infection requiring intensive treatment, revision surgery, and rarely, severe vision loss. Cataract (hazy lens) occurs more often after glaucoma surgery. In fact, there is evidence that all of the glaucoma treatments speed up the development of cataract. While this is undesirable, cataract is surgically removable.

At present, more patients choose eye drops than laser or surgery as their first glaucoma treatment. Yet, a recent large study found that those with serious glaucoma damage did as well or better with first surgery than the comparison group who took eye drops first. Patients who find surgery to be a good first choice are people who can tolerate a bit higher risk, as well as those who feel that they are generally not good at remembering to take medication. Surgery is a good option, then, for those who would like to have the treatment that most allows them to “forget about” their glaucoma.

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