One Third of Sleep Apnea Patients in Study Diagnosed With Glaucoma

November 18, 2003

Karla Harby

Nov. 18, 2003 (Anaheim) — In an ongoing, prospective study of 83 patients with obstructive sleep apnea (OSA), glaucoma was diagnosed in 27 (33%) of the study subjects. Only four had been previously diagnosed and treated, according to Rick E. Bendel, MD, from the Mayo Clinic in Jacksonville, Florida.

Based on this and earlier observations suggesting an association between the two conditions, Dr. Bendel recommends that all sleep apnea patients be screened for glaucoma. "OSA may be a modifiable risk factor that is easily treatable," he told an audience at the annual meeting of the American Academy of Ophthalmology.

The moderator of the session, James C. Tsai, MD, from Columbia University in New York City, spoke with Medscape afterward and said that the 33% prevalence of glaucoma found in this population "...is a big deal..." compared with the 1.5% to 2.5% prevalence of this disease in the general population. "This is underappreciated," he added. "As more prospective series are done, we're going to have to address this with our patients."

Karanjit S. Kooner, MD, from the University of Texas at Dallas, agreed that patients with sleep apnea are prime candidates for thorough ophthalmologic examinations. "This study shows, in a very well designed fashion, that there is another risk factor for glaucoma for us to consider," he told attendees during his discussion. "These patients need to be sent to sleep disorder centers. There is a lot of good treatment available."

Dr. Bendel's team used the strictest criteria in this study for diagnosis of sleep apnea, an apnea-hypopnea index (AHI) of at least 15. According to Dr. Bendel, this meant that apnea, hypopnea or both occurred 15 or more times per hour in these subjects. Glaucoma was defined as multifactor optic neuropathy diagnosed by changes in the optic nerve, or abnormalities of the visual field, or both.

"Our study rationale looked at OSA because it causes profound changes in oxygenation, circulatory hemodynamics, and inflammatory factors," Dr. Bendel said. "All of these may influence optic nerve integrity and possibly intraocular pressure, as well."

This interim analysis was based on 83 of 100 patients expected to participate. Among the study subjects, six were nonwhite and 51 (61%) were men. The median age was 62 years; the median body mass index (BMI) was 35 (with a BMI of 30 or greater defining obese); and the median AHI was 37 — "meaning a lot of our patients stopped breathing about 40 or more times per hour," Dr. Bendel explained. Median intraocular pressure (IOP) was 16 mm Hg.

Two of the patients under study (2.4%) had ocular hypertension. "This is something I would expect in the population at large," Dr. Bendel said. "However, I wasn't expecting to find 33% of the patients with a diagnosis of glaucoma." Of these, 17 patients (63%) had glaucoma using the more strict definition of visual field plus optic nerve abnormalities; six patients (22%) were diagnosed by optic nerve changes alone; and four patients (15%) had a previous diagnosis and treatment by an outside ophthalmologist.

None of the variables examined, including age, sex, BMI, AHI, and IOP, were statistically significant predictors of which patients would be diagnosed with glaucoma, Dr. Bendel reported. Associating these same variables with IOP, only two showed statistical significance: the IOP tended to be lower in men ( P = .04), and as the BMI increased, the IOP increased ( P = .04). Specifically, the IOP increased about 0.5 mm Hg per an increase of five units of BMI, he said.

Patients with OSA are already known to be at higher risk for motor vehicle collisions, myocardial infarctions, strokes, and premature death. "Perhaps glaucoma will one day be added to this list," Dr. Bendel said.

This study was independently funded. The authors reported no pertinent financial disclosures.

AAO 2003 Annual Meeting: Free Papers. Presented Nov. 17, 2003.

Reviewed by Gary D. Vogin, MD

Karla Harby is a freelance writer for Medscape.

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