Link Found Between Cognitive Impairment and Normal-Tension Glaucoma

With the recent discovery of a link between normal-tension glaucoma (NTG) and dementia, researchers now believe cognitive impairment could be more strongly associated with NTG than high tension glaucoma (HTG).

A team, led by Sean Mullany, MD, Ophthalmology, Flinders University, used cognitive screening data from the Australasian Glaucoma Disease Registry to identify the link between cognitive impairment and high tension glaucoma.

In the case-control cross-sectional study, the investigators completed a cognitive screening assessment in 290 age-matched and sex-matched NTG individuals N = 144) with HTG controls (n = 146) randomly sampled from the Australian and New Zealand Registry of Advanced Glaucoma.

Cognitive Screenings

The investigators performed cognitive screenings on the patient population, which were aged 65 years and older, using the Telephone Version of the Montreal Cognitive Assessment (T-MoCA), which omits points requiring visual interpretation, accounting for confounding factors related to vision loss in the visually impaired participants.

The team defined cognitive impairment by a T-MoCA score of less than 11 out of 22.

The researchers then compared cognition between NTG and HTG groups using predetermined thresholds and absolute screening scores.

Overall, there were no differences in the 2 cohort demographics or ocular parameters at baseline.

Results Between the Two Cohorts

The results show cognitive impairment was more prevalent in the normal-tension glaucoma cohort (OR, 1.2; 95% CI, 1.1-6.7; P = 0.030).

After examining a linear trend, the investigators found lower absolute T-MoCA scores in the NTG arm of the study when compared to the high tension glaucoma cohort. However, this trend was not deemed to be statistically significant (P = 0.108).

“This study demonstrated an association between NTG status and poor cognition, supporting the hypothesis that there exists a disease association and shared pathoaetiological features between NTG and dementia,” the authors wrote.

Link Between Glaucoma and Pollution

Along with cognitive impairment, researchers have found other links involving glaucoma patients.

In 2019, an analysis of more than 100,000 revealed people living in neighborhoods with a greater amount of fine particulate matter (PM2.5) were at least 6% more likely to report having glaucoma.

In an effort to evaluate how increased levels of air pollution could play a role in glaucoma, investigators conducted an assessment on 111,370 participants in the UK Biobank study cohort.

Upon analyses, investigators observed patients in areas with higher PM2.5 concentration were at least 6% more likely to report a diagnosis of glaucoma compared to those in the less polluted areas(OR, 1.06, 95% CI, 1.01-1.12, per IQR increase P= 0.02).

Additionally, investigators noted associations between patients living in an area with higher PM2.5 concentration and thinner GCIPL as well as a dose-response relationship between higher levels of PM2.5 and thinner GCIPL (P<0.001). No clinically relevant relationship was observed between PM2.5 concentration and IOP.

Despite the study focusing on the patients in the United Kingdom, investigators suggest the results highlight the need for further research to evaluate the potential link between particulate matter exposure and glaucoma.

The study, “Normal-tension glaucoma is associated with cognitive impairment,” was published online in the British Journal of Ophthalmology.