Changes in tear flow and tear film stability after photorefractive keratectomy

Purpose. To investigate the changes in tear flow and tear film stability af ter photorefractive keratectomy (PRK) for myopia. Material and Method. One eye of 32 patients underwent unilateral PRK procedure for the correction of myopia ranging from -1.50 to -6.00 diopters (D) (mean -3.65 +/- 1.55 D). S chirmer test values and break-up time (BUT) scores were measured 6 weeks af ter the PRK procedure. Unoperated, contralateral eyes were used as control eyes for each patient. The Schirmer test scores and BUT values were statist ically analyzed using independent t test. Results. The mean Schinner test v alue was 14.45 +/- 7.79 mm in the operated eyes. It was 28.83 +/- 5.89 in t he control eyes. The decrease in Schirmer test value was statistically sign ificant (t = 8.28, p = 0.0001). The mean BUT scores were 13.19 +/- 5.09 s i n the operated eyes and 27.83 +/- 9.31 s in the control eyes. The decrease was statistically significant (t = 7.86, p = 0.0001). Conclusion. PRK cause s a decrease in tear flow and tear film stability that is probably caused b y decreased corneal sensation after PRK.