Study pulls back covers on links between glaucoma and sleep

A recent study reports that abnormal sleep patterns may be risk factors for or consequences of glaucoma.

In the recent cross-sectional study, "Association Between Sleep Parameters and Glaucoma in the United States Population: National Health and Nutrition Examination Survey," researchers reviewed data from the survey's nearly 6,800 patients over 40 years of age who responded to the sleep questionnaire between 2005 and 2008. The primary purpose of the study, which appeared in the Journal of Glaucoma in February, was to investigate further the relationship in the population.

While past studies have looked at the link between glaucoma and covered topics such as shorter sleep duration, prolonged sleep latency, lower sleep efficiency and poorer sleep quality, study researchers took another tact, noting the "paucity" of papers on glaucoma and the role of "excessive sleepiness."

Among the in-depth survey questions: how long respondents typically slept per night; how long it took for them to fall asleep; quality of that sleep; whether or not they had previously been diagnosed with a sleep disorder (i.e., apnea, insomnia, restless leg syndrome); and their ability to function during the day.

Among the findings by researchers affiliated with Wilmer Eye Institute at Johns Hopkins University:

• Odds of disc-defined glaucoma were three times higher among study participants who slept for more than 10 hours per night, compared with those who slept seven hours per night, which was the mean sleep duration reported by those surveyed.
• Odds of glaucoma were two times higher among respondents who fell asleep in nine minutes or less and in 30 minutes or more, compared to those who slept between 10 and 29 minutes (norm).
• Odds for visual field defects (VFDs) were three times higher among participants who slept for three or fewer hours and 10 or more hours per night, compared to respondents who reported sleeping seven hours a night (norm).
• Odds of VFDs were two times higher among study participants who had difficulty remembering things, and three times higher among participants who had difficulty working on a hobby, "due to excessive daytime sleepiness."

The authors write: "This study revealed associations between glaucoma and abnormal sleep duration, sleep latency, and daytime dysfunction; poor sleep parameters may be a risk factor for or a consequence of glaucoma."

About 3 million Americans have glaucoma, and it's the second leading cause of blindness in the world, according to the Centers for Disease Control and Prevention.

The AOA Evidence-Based Optometry Committee is currently developing an evidence based clinical practice guideline on the topic of glaucoma. The committee is extensively reviewing, grading and collaborating all the current global literature and developing the comprehensive guideline for potential release in 2020.

The relationship between glaucoma and sleep: Is there one?

Whether sleep problems are associated with glaucoma has been the subject of debate and study for years, says Murray Fingeret, O.D., chief of the optometry section, Brooklyn/St. Albans campus, Department of Veterans Administration New York Harbor Health Care System. Dr. Fingeret also is a clinical professor at State University of New York College of Optometry.

Many doctors of optometry are under the impression that sleep apnea is a risk factor for glaucoma, and while there are numerous studies that show an association, there are many that do not, Dr. Fingeret says.

"What makes these questions interesting is that a subpopulation of retinal ganglion cells that project to the suprachiasmatic nucleus (and may be damaged in glaucoma) mediate both vision and non-vision pathways (such as sleep)," Dr. Fingeret says. "Experimental models have shown that when IOP (intra-ocular pressure) is elevated in animals, these pathways are damaged. This sets the possibility that there may be a relationship between glaucoma and sleep.

"This study did not find an association between diagnosed sleep disorders such as sleep apnea and glaucoma but did find an association between glaucoma and abnormal sleep patterns including too little or too much sleep, sleep latency (inability to go to sleep easily) and daytime problems related to being tired," he adds. "Whether sleep dysfunction is a byproduct of glaucoma or a risk factor for it still needs to be resolved, but this study addresses some interesting questions."

Researchers recommended additional study.