Darker skin color has often been cited as a potential risk factor for glaucoma; however, a new study suggests a person’s skin pigmentation doesn’t appear to be linked to the ocular disease. 

The case-control investigation was conducted at Menelik II Tertiary Referral Hospital in Addis Ababa, Ethiopia and enrolled patients aged 40 and older who were scheduled for trabeculectomy at the glaucoma clinic, in addition to a control group of aged-matched, healthy subjects. Researchers captured objective melanin measurements in triplicate from the inner arm of each participant.

“It is well known that African descent is a risk factor for open-angle glaucoma. Studies many decades ago implicated pigmentation as possible risk factor, but those studies used subjective assessments of skin color,” says researcher Jeremy Keenan, MD. To better understand the link between skin pigmentation and glaucoma risk, the researchers a relatively new colorimeter, which helped them record more objective melanin measurements of the inner arm, Dr. Keenan says. In this study, they focused on patients with and without glaucoma in Ethiopia.

“When we compared the two groups, we didn’t find strong evidence that skin melanin levels were associated with having glaucoma,” Dr. Keenan says. “Thus, at present, there is little evidence to support using skin pigmentation levels when assessing risk for glaucoma.”

The study found the agreement between the triplicate inner arm melanin measurements was high, with an intra-class correlation of 0.99. Mean melanin values were 704 units in 76 cases and 694 units in 152 controls. Additionally, the study found no statistically significantly association between melanin and glaucoma after adjusting for sex and season of measurement (i.e., dry vs. rainy), with an odds ratio of 1.15 per 100 units of inner arm melanin.

Giorgis A T, Alsoudi A, Alemu A, et al. The relationship between melanin and glaucoma a case-control study. Journal of Glaucoma. September 3, 2020. [Epub ahead of print].