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Early changes to dry eye and ocular surface after small-incision lenticule extraction for myopia.

AIM
To investigate the early changes in dry eye symptoms, tear function and ocular surface following small-incision lenticule extraction (SMILE) for myopia.


METHODS
Ninety-seven consecutive patients (193 eyes) who underwent SMILE for myopia were observed in this longitudinal and retrospective study. Parameters evaluated included: subjective dry eye symptoms (dryness, foreign body sensation and photophobia), tear film breakup time (TBUT), Schirmer I test (S I T) without anesthesia, tear meniscus height (TMH) and corneal fluorescein staining. Each parameter was evaluated before, and subsequently at 1d, 1wk, 1 and 3mo after surgery.


RESULTS
Compared with preoperative data, dryness was noted to be significantly increased at 1wk and 1mo postoperatively (P<0.01). Symptoms of photophobia and foreign body sensation demonstrated significant differences at 1d and 1wk as compared with preoperative scores respectively (P<0.01). These values were decreased at 1 and 3mo post-surgery (P>0.05). Conversely the corneal staining scores were higher than the preoperative data at 1d, 1wk and 1mo (P<0.01), but were close to the preoperative level at 3mo postoperatively. There was a significant decrease in TMH at 1wk and 1mo (P<0.01), but the value was close to the preoperative level at 3mo postoperatively (P=0.16). The examination outcomes of S I T were significantly increased at 1d then reduced at 1wk after surgery (P<0.01). Each value subsequently returned to the baseline value at 1 and 3mo (P>0.05). TBUT was significantly decreased at all postoperative time points (P<0.01).


CONCLUSION
SMILE resulted in mild dry eye symptoms, tear film instability and ocular surface damages; however, these complications can recover in a short period of time.