Intraocular (internal eye) pressure, or IOP, is the only glaucoma risk factor currently approved for medical treatment. The search is on, however, for other modifiable everyday factors that might slow or halt glaucoma progression. Researchers at the World Glaucoma Congress presented the latest research findings regarding five potential glaucoma risk factors, specifically:

• Diet,
• Air pollution,
• Physical activity,
• Systemic medication, and
• Sleep.

Diet and glaucoma risk

A growing number of studies are linking diet and eye health. According to Mount Sinai ophthalmologist Louis Pasquale, M.D., his own research revealed that greater caffeine intake was associated with higher IOP and glaucoma in people who have a strong genetic susceptibility to them.

A pre-clinical study also suggested that niacinamide (vitamin B3) may provide neuroprotection against glaucoma by increasing the function of cell mitochondria, where energy is made.

Based on these results, Pasquale concluded that dietary supplements may be an effective add-on therapy, and that the potential role of genetics in the relationship between diet and glaucoma merits further study.

Air pollution and glaucoma risk

Research has shown that air pollution promotes disease through inflammation and oxidative stress. Professor Paul Foster, Ph.D. of University College London reported that one of his more recent studies showed that:

• High exposure to black carbon, in particular, increased IOP in people genetically susceptible to oxidative stress, and
• Higher exposure to airborne particles significantly increased glaucoma risk and affected macular ganglion cells, regardless of IOP.

Physical activity and glaucoma risk

Ophthalmologist Pradeep Ramulu, M.D. of Johns Hopkins University discussed two studies on the relationship between physical activity and glaucoma. 

One study, which assessed participants’ daily footsteps and minutes of physical and non-sedentary activity, found that more walking and time spent being physically active was associated with slower vision loss in glaucoma patients who were undergoing treatment.

A second study monitored nearly 30,000 male runners for 7.7 years, and found that glaucoma risk declined 5% for each kilometer (0.62 miles) per run, suggesting glaucoma risk can be lowered with vigorous exercise.

Ramulu suggested that glaucoma patients should be encouraged to exercise in addition to following the standard IOP-lowering therapy.

Systemic medications and glaucoma risk

Systemic medications can have various effects on glaucoma. Several classes of drugs in particular, said U.K.-based consultant ophthalmic surgeon Anthony Kwahaja, MBBS, Ph.D., have been observed to affect the risk of developing glaucoma.

• Steroids and calcium channel blockers have been found to increase open-angle glaucoma risk.
• Anticholinergics and sulfonamide-derived drugs have been shown to increase the risk of angle-closure glaucoma.

In other studies:

• Systemic beta-blockers lowered glaucoma risk by moderating blood pressure, and
• Selective serotonin reuptake inhibitors (SSRIs), particularly citalopram, reduced primary open-angle glaucoma (POAG) risk.

Kwahaja recommends that patients periodically provide their eye doctors with a list of their current medications. He also made the point that drug-glaucoma associations are often influenced by underlying medical issues, race/ethnicity, prescribing patterns, and other factors. 

Sleep and glaucoma risk

David Mackey, M.D. of the University of Western Australia said research on obstructive sleep apnea (OSA) and open-angle glaucoma is still unclear. Data from several large studies like the U.K. Biobank shows a link between OSA and glaucoma. Another study, however, found a possible link between OSA and retinal fiber thinning in young adults, but not so much in middle-aged adults. Mackey encourages further research on how continuous positive airway pressure (CPAP), a common OSA therapy, affects the optic nerve.

*World Glaucoma Association. (n.d.). The Hunt for New Modifiable Risk Factors for Glaucoma. https://wga.one/wga/education-committee-highlights-wgc-2021-part-1-3