Evaluating MMP-9 levels may help diagnose dry eye

This prospective study found that a test that monitors matrix metalloproteinase 9 (MMP-9) levels is sensitive and specific in diagnosing dry eye.

MMP-9 is an inflammatory biomarker that has been shown to be elevated in the tears of patients with dry eyes. The authors administered an immunoassay test called InFlammaDry on 143 patients with clinical signs and symptoms of dry eye confirmed by clinical examination and 63 healthy individuals serving as controls. The test is designed to detect abnormally elevated MMP-9 present in the late phase of the inflammation cycle and therefore may be more clinically relevant than causal mechanisms or acute symptoms. The results are available in 10 minutes.

InflammaDry showed a sensitivity of 85 percent, specificity of 94 percent, negative-predictive value of 73 percent, and positive predictive value of 97 percent. False-negatives occurred uniformly across all levels of dry-eye severity, which suggests they may have been the result of inadequate collection and transfer of tear samples.

Although MMP-9 activity is elevated in symptomatic dry eyes, as well as in other clinically easily identifiable ocular surface conditions, InflammaDry also reveals asymptomatic ocular surface disease and the hidden inflammation of dry eyes. The authors say that patients with positive test results with InflammaDry may benefit from treatment with anti-inflammatory therapy, while those with negative results and a positive clinical examination may have dry eye without significant accompanying inflammation and may benefit from artificial tear replacement or punctal occlusion. If artificial tears are ineffective at relieving symptoms, a therapeutic trial of anti-inflammatory therapy to target subclinical inflammation may be necessary.

They conclude that the ability to accurately detect elevated MMP-9 levels may lead to earlier diagnosis, more appropriate treatment and better management of ocular surface disease.