Open-Angle Glaucoma: Still Unclear Which Treatment Is Best

Lara C. Pullen, PhD

February 18, 2013

A systematic review commissioned by the US Preventive Task Force (USPSTF) confirms that treatment of open-angle glaucoma can lower intraocular pressure and reduce the risk for optic nerve damage. However, the reviewers were unable to determine which medical or surgical treatment is best able to prevent visual disability and improve patient-reported outcomes.

Michael V. Boland, MD, PhD, and colleagues from Johns Hopkins University School of Medicine in Baltimore, Maryland, published the results of their systematic review online February 18 in the Annals of Internal Medicine. The review included and relied heavily on existing systematic reviews (through March 2, 2011) but also included primary studies (through July 30, 2012). The authors excluded studies that did not stratify analyses by glaucoma type.

A major limitation of the review was that outcomes of glaucoma treatment are inadequately standardized. Moreover, there is little to no research linking treatment and prevention of optic nerve structural damage and visual field loss.

Albert L. Siu, MD, MSPH, co–vice chair of the USPSTF, spoke with Medscape Medical News about the USPSTF-requested review. He acknowledged its limitation in a telephone interview, saying that although the review concluded that treatment is effective, "It is less clear that treatment reduces vision problems and long-term outcomes."

The authors identified high-level evidence that suggests that the medical treatment of glaucoma decreases intraocular pressure (IOP) and protects against worsening visual field loss. The review points to a role for medical, surgical, and laser treatments in decreasing IOP in patients with glaucoma. There was insufficient evidence to compare the effectiveness of any of the glaucoma treatments on visual impairment or patient-reported outcomes.

Long-term Comparisons Needed

"Landmark studies have established that IOP reduction preserves visual function," said L. Jay Katz, MD, chief of the Wills Eye Glaucoma Service in Philadelphia, Pennsylvania, who discussed the review with Medscape Medical News. "Furthermore, the extent of IOP lowering correlates with the success of visual field stability in large population trials. However, it is challenging to obtain funding to support long-term trials with large populations that would compare different drugs; for example, in the preservation of structure (optic nerve) or function (perimetry)."

The reviewers identified prostaglandins as the most effective topical medication for decreasing IOP. The most common incisional surgery for glaucoma is trabeculectomy.

Although laser trabeculoplasty is consistently effective at decreasing IOP, there are not enough data to determine the best laser to use or the optimal number of applications. The authors note that when compared with nonpenetrating procedures such as deep sclerectomy or viscocanalostomy, trabeculectomy produces more adverse effects such as hypotony, hyphema, and shallow anterior chambers.

"The paper strongly validates what we currently practice as consensus thoughts in the management of open-angle glaucoma," Dr. Katz said. "The article validates that pressure reduction is important." He added, "Glaucoma management cannot be relegated to a simple stick diagram approach.... [Physicians need to] individualize with the patient what may be best for them after an informed decision making discussion."

Anne L. Coleman, MD, PhD, from the Jules Stein Eye Center in Los Angeles, California, also commented on the article. She told Medscape Medical News that, "This report will not change clinical practice because currently ophthalmologists treat glaucoma patients with medications, lasers and/or incisional surgery to prevent progressive vision loss and optic nerve damage. This report does highlight the need for comparative effectiveness studies comparing alternative treatments of glaucoma so that clinicians have some guidance on which treatment may be better at different stages of the disease. Fortunately, there is currently an ongoing study [the Registry in Glaucoma Outcomes Research] investigating the treatment of glaucoma with medications, laser or surgery." Dr. Coleman is one of the investigators of that study.

The authors and commentators have disclosed no relevant financial relationships.

Ann Intern Med. 2013;158:271-279.

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