Evaluation of Tear Osmolarity Changes After Photorefractive Keratectomy

Purpose: To assess tear film stability, ocular surface disease index (OSDI) score, Schirmer test value, tear film breakup time (TBUT), and tear osmolarity after photorefractive keratectomy (PRK). Methods: We enrolled 50 eyes from 25 patients who were PRK candidates (15 men, 10 women). The mean age was 31.9 +/- 4.5 years. Dry eye severity was evaluated using OSDI questionnaire, TBUT, Schirmer test, and tear osmolarity preoperatively and in each postoperative follow-up visit during the 4-month follow-up period. Results: Tear osmolarity changed from 302 +/- 5.9 mOsm/L preoperatively to 308.8 +/- 5.8 mOsm/L (P < 0.0001) and 304.1 +/- 9.4 mOsm/L (P = 0.40) after 2 and 4 months, respectively. Schirmer test did not change significantly 4 months after PRK (P = 0.410). TBUT decreased significantly after 2 months and did not return to its preoperative value after 4 months. Subjective complaints measured by OSDI score, improved after 4 months compared with the preoperative level. Conclusions: Although dry eye tests (Schirmer, TBUT, and tear osmolarity) are abnormal 2 months after PRK, they returned to preoperative values after 4 months. We can conclude that post-PRK dry eye is a transient complication which will last less than 4 months with regular use of topical lubricants.