Glaucoma: A General Overview of the Disease

Other possible risk factors include diabetes and myopia (nearsightedness), however studies have provided inconsistent results as to the degree of association with these factors.

Diagnosing Glaucoma

Your physician will perform a complete medical history and eye examination in order to determine your risk factors and to search for signs of disease. The entire eye will be carefully evaluated, with special attention paid to the optic nerve, the structure damaged by glaucoma. The optic nerve is viewed through your dilated pupil using a special lens and an ophthalmic microscope. Gonioscopy may also be performed, in which a special mirrored lens in placed on your eye in order to directly examine the drainage angle and trabecular meshwork. The thickness of your cornea may also be measured, as an abnormally thick or thin cornea can affect the accuracy of intraocular pressure measurement. After your exam, if glaucoma is suspected, additional tests may be recommended, such as:

Treatment for glaucoma is individualized for each patient’s specific condition. When required, three basic options are available, all of which serve to lower the intraocular pressure.

Initial therapy has traditionally been medications, applied topically as eye drops. Medications lower pressure by either decreasing the production of fluid within the eye or by opening the drainage system to allow more fluid out. There are numerous classes of medications available, each with its own set of side effects. Your doctor will suggest medications for you based upon their safety and efficacy, taking your general health and use of other medications into account.

 Another treatment option is a laser procedure, known as selective laser trabeculoplasty, or SLT. A variation of this procedure has been safely performed since the early 1980s. The treatment is performed in the physician’s office with the patient comfortably seated at a clinical microscope. Over a period of about five minutes, the laser light is directed at the trabecular meshwork within the eye, serving to “unclog” the eye’s drain and allow more fluid to exit. Postoperatively, one can expect mild discomfort, sensitivity to light, and slightly blurred vision for a few days. There is a 60 to 90 percent success rate of lowering intraocular pressure by approximately 15 to 30 percent. Success may be impacted by a number of factors, including current use of eye medications. The treatment effect lasts, on average, two to five years, and can later be repeated if necessary. A large, randomized clinical study published in 2019 (known as the LiGHT trial) found that SLT and medication are equally effective at lowering IOP in patients who have not been previously treated for glaucoma or high IOP. The patients who underwent initial SLT maintained well-controlled IOP for 3 years without drops. Given the extremely good safety profile and efficacy of the procedure, SLT is a good first-line option for those who do not want to take daily medication for glaucoma. Your doctor will determine if you are a good candidate for this procedure based upon your eyes’ anatomy.

The final treatment option, when medications and laser therapy have either failed or are no longer tolerated, is surgery. Traditional glaucoma “filtering surgery” serves to bypass the damaged, clogged drainage system of the eye. In effect, a new drain is surgically created, allowing the aqueous humor to escape the eye without having to pass through the clogged trabecular meshwork. The most commonly performed operation, called a trabeculectomy, often produces very low eye pressures, lower than can be achieved with medication or laser. Such low pressures are often required in advanced glaucoma to prevent further loss of vision. Occasionally, another procedure, known as a tube shunt or glaucoma drainage device, may be required. In this type of surgery, a tiny plastic tube is inserted into the eye to drain fluid. The type of glaucoma and the condition of your eye will influence your physician’s decision regarding which procedure to perform. While effective and safe, surgery entails more risks than other therapies and serious complications, although rare, can occur.

Newer surgical techniques seek to avoid bypassing the eye’s natural drainage canal in favor of trying to re-establish a more normal drainage pathway through the damaged trabecular meshwork. Known collectively as ‘micro-invasive glaucoma surgery,” or MIGS, numerous procedures have been and continue to be developed. These include tiny stents that can be placed through the trabecular meshwork and into the eye’s main drainage canal, and are typically implanted at the time of cataract surgery. Other options include dilating and cleaning out the eye’s drainage system or removing sections of the trabecular meshwork to gain more direct access to the drainage system. While effective at lowering intraocular pressure, these surgical techniques generally cannot achieve pressures as low as with the previously mentioned filtering surgeries. Therefore, decisions about which surgical procedure to perform must take into account many factors, including patient age, ocular anatomy, severity of disease, and level of post-operative IOP required.