Study suggests link between selenium levels, pseudoexfoliation syndrome

Am J Ophthalmol. 2011;151(2):272-276.

Issue: April 10, 2011

Low levels of an essential trace element in the aqueous humor, conjunctiva and serum may play a role in the development and progression of pseudoexfoliation syndrome, a study found.

The trace element, selenium (Se), is known to have antioxidant properties.

"Our findings on decreased concentrations of Se in both ocular specimens and serum of [pseudoexfoliation] patients support the ocular and systemic involvement of the disease," the study authors said. "Selenium depletion also emphasizes impaired balance in the antioxidant status of the eye."

The prospective study included 27 cataract patients with pseudoexfoliation (PEX) syndrome and 20 age-matched cataract patients without PEX. Mean patient age was 73.5 years in the study group and 74.5 years in the control group. All patients underwent standard phacoemulsification.

Study results showed that patients with PEX syndrome had a mean Se level in aqueous humor of 50.96 µg/L. Controls had a mean level of 77.85 µg/L. The difference was statistically significant (P < .001).

Mean Se levels were 4.04 µg/L in conjunctival specimens from patients with PEX syndrome and 7.19 µg/L in specimens from controls. The difference was statistically significant (P < .001).

Mean levels were 115.25 µg/L in serum samples from patients with PEX and 124.25 µg/L in samples from controls. The difference was statistically insignificant.

"Further studies are required to investigate the role of essential trace elements in the development and pathogenesis of PEX syndrome to support our findings," the authors said.

This report of decreased levels of selenium, an essential trace element, in the aqueous humor and conjunctival tissue of pseudoexfoliation compared to non-pseudoexfoliation cataract eyes by Yilmaz and colleagues adds another piece to the puzzle regarding the pathogenesis of pseudoexfoliation syndrome. Serum levels of selenium were not found to be statistically different, suggesting this finding may be specific for the eye. Evidence of elevated plasma homocysteine levels, molecular changes associated with expression levels of extracellular matrix (ECM) proteins, an association with LOXL1 (an ECM protein) gene polymorphisms, and possible systemic disease associations such as increased risk of cerebro- and cardiovascular disease, along with the presence of pseudoexfoliation material throughout the body, suggest that pseudoexfoliation is a systemic disease associated with ECM metabolism. Decreased selenium levels in pseudoexfoliation eyes may additionally implicate oxidative change as a risk factor for development of glaucoma, because some selenoproteins regulate oxidative stress. Regulation of oxidative change in pseudoexfoliation eyes could represent a new avenue of treatment for pseudoexfoliation glaucoma if decreased selenium levels are causative and not a consequence of more basic cellular and molecular changes associated with pseudoexfoliation glaucoma pathogenesis.

– Richard K. Lee, MD, PhD
Associate Professor of Ophthalmology, Cell Biology and Anatomy, and Neuroscience, Bascom Palmer Eye Institute, Miami
Disclosure: Dr. Lee has no relevant financial disclosures.