Changes in tear protein pattern after photorefractive keratectomy

PURPOSE. Changes in tear protein composition of patients who underwent photorefractive keratectomy (PRK) were analyzed. METHODS. Tear samples were obtained from 23 eyes of 23 patients immediately before PRK and on the fourth postoperative day with glass capillaries. Tear proteins were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Digital image analysis and evaluation of the densitometric data of the electrophoretic separations were done with BioDoc-Analyze. RESULTS. Analysis of discriminance found a significant difference in the protein patterns (p<0.001). This type of analysis of the electrophoretic densitographs uses all peak information simultaneously. A significant decrease (p<0.005) in three of the main protein peaks - lactoferrin, immunoglobulin A heavy chain, and lysozyme - was also found after PRK. CONCLUSIONS. Excimer laser ablation of the cornea has an acute effect on lacrimal gland protein secretion. Changes in tear composition may lead to feelings of dryness and to a decrease in tear film stability postoperatively.