Non-invasive assessment of the tear film after LASIK

OBJECTIVE: The aim of the study was to compare the assessment of the ocular surface using classic methods with the newly developed keratoscopy-based MYAH (Topcon EU, Vi -sia Imaging, Japan) device after femtosecond la-ser-assisted in situ keratomileusis (LASIK). PATIENTS AND METHODS: This cross-sec-tional and observational study analyzed 80 eyes of 40 patients. Tear film and ocular surface eval-uation were performed at baseline, postoperative week 1, and month 1. Measurements obtained using the Schirmer I test and invasive tear-film breakup time (I-TBT) were compared with non-in-vasive evaluation of the tear break-up time (NI-TBT), tear meniscus height (TMH) and blink analysis obtained using the MYAH device. Findings were correlated with the Ocular Surface Disease Index (OSDI) questionnaire in all subjects.RESULTS: The study included 80 eyes of 40 consecutive patients (21 males and 19 females) with a mean age of 26.6 +/- 5.9 years (18-40 years) and a mean spherical equivalent value of -3.64 D (-9.63 to -0.25 D). There was a significant de-crease in Schirmer I test (19.21 +/- 8.4 vs. 16.61 +/- 9.1 vs. 14.69 +/- 9.86, p= 0.02, respectively) and I-TBT values (8.59 +/- 3.4 vs. 7.4 +/- 3.25 vs. 6.17 +/- 3.01, p=0.03 respectively). OSDI values showed a significant increase after LASIK (11.56 +/- 6.3 vs. 17.24 +/- 7.5 vs. 14.71 +/- 9.6, p=0.03, respectively). 5% level NI-TBT was significantly lower at 1 week 6.75 and 1 month 7.45 than baseline 13.2 at follow-up (p=0.037). Ocular protection index (6.6 vs. 2.3 vs. 2.6, p=0.009, respectively) and blink/minutes (18 vs. 17 vs. 15, p=0.002, respectively) values showed a statistically significant decrease. Our data detected a weak correlation between I-TBT and noninvasive first TBT, 5% level TBT parameters at month 1 follow-up. This study also found no correlation be-tween contact lens use, older age, female gender, and pre-operative refractive error with the noninvasive MYAH dry eye parameters.CONCLUSIONS: This study demonstrated the ability of the new keratoscopy-based MYAH de -vice to detect changes in the short term after LASIK surgery.