Tear Organic Acid Analysis After Corneal Collagen Crosslinking in Keratoconus.

OBJECTIVES This study examined changes in the levels of organic acids, which are important tear metabolites, after corneal collagen crosslinking (CXL) treatment for keratoconus. METHODS This prospective, nonrandomized, interventional case series included a single eye from 24 patients who were scheduled to receive CXL treatment (Dresden protocol) for progressive keratoconus. Before CXL treatment and at 6 months after treatment, tears were collected in capillary tubes. The patients were separated into four groups as males, females, and ages 18 years younger and >18 older. The organic acid profiles of the tear samples were analyzed using mass spectrometry. RESULTS An evaluation was made of 12 females and 12 males with a mean age of 19.20±4.06 years (range: 12[FIGURE DASH]27 years). The greatest percentage increase in organic acids after CXL treatment was observed for N-acetyl-L-aspartic acid (66% increase). The organic acid showing the greatest decrease was 3-OH butyric acid (61% decrease). A decrease of 46% was found (P=0.263) in the lactic acid/malic acid ratio. CONCLUSION Metabolomic studies of tears could facilitate a new and objective process in the follow-up period or in the determination of prognosis after CXL treatment for diseases such as keratoconus, which has a multifactorial etiology.