Purpose: To evaluate changes in tear function following myopic LASIK with thin femtosecond flaps.
Subject and methods:
We enrolled 60 eyes of 44 patients who were undergoing correction of low to moderate myopia with femtosecond LASIK. The clinical assessments include Schirmer test with and without anesthesia, sodium fluorescein tear breakup time and impression cytology at 1, 3, and 6 months after femtosecond LASIK.
Results:
The mean Schirmer score was 12.9 +/-4.9mm preoperatively and 11.6 +/-4.3(p=0.65), 12.3 +/-4.1mm (p=0.85), and 12.4+/-4.4mm (p=0.88) at 1 week and 3 and 6 months postoperatively, respectively.
The mean tear breakup time was 7.2 +/-2.3 seconds preoperatively and 8.0 +/-3.2(p=0.45), 8.7 +/-4.3 (p=0.55), and 8.3 +/-4.2 (p=0.48) seconds at 1 week and 3 and 6 months postoperatively, respectively.
All patients, showed a decrease in Conjunctival GCD until the third month after Femtosecond LASIK. There was a significant decrease at 1 week (P > 0.001), and 3 months (P > 0.001) after LASIK, but at 6 months we found no significant difference (P =0.65) compared with preoperative values.
Conclusion:
There are time-dependent changes in the conjunctival morphology and clinical parameters of tear function after femtosecond LASIK.
Femtosecond LASIK does not have an adverse effect on dry eye signs at 6 months postoperatively.
Introduction:
Laser in situ keratomileusis (LASIK) is the most common refractive procedure for the correction of mild to moderate myopia and different devices are used to create the corneal flap before the LASIK ablation (Sugar A. et al, 2002 and Sandoval HP et al, 2005).
Advances in the techniques and instruments have reduced the incidences and severity of flap abnormalities and other potentially severe complications of LASIK. The lamellar cut to fashion the flap for LASIK can be performed using a mechanical microkeratome or a femtosecond laser (Marcella Q et al, 2009).
Mechanical microkeratomes are more commonly used and a rapid visual recovery is observed with minimum discomfort for the patients and reproducibility of the refractive effect (Solomon KD et al, 2004). The femtosecond laser is an automated flap creation device for LASIK and is a safe and effective alternative to traditional mechanical microkeratomes (Nordan LT et al, 2003). It may provide greater safety, reproducibility, predictability, and flexibility of the flap-making procedure and minimize interface deposits, epithelial defects, and striae (Touboul D. et al, 2005).
Many studies have reported dry eye as the most frequent complication after LASIK, and many theories of pathogenesis have been proposed for this phenomenon (Battat L.et al ,2001, Toda I et al, 2001 and Knorz MC, 2006). Among these are the damage of the corneal nerve plexus (Linna TU et al,2000 , Donnenfeld ED et al,2004) , tear film instability, and the reduction of conjunctival GCD ( Patel S et al ,2001, Albietz JM et al ,2002, Boire MM et al, 2003).
Conjunctival GCD and epithelial cell morphology constitute an objective way to evaluate the status of the ocular surface, in that conjunctival GC are responsible for the production of gel forming mucin, MUC5AC (Jumblatt MM et al , 1999).
The most important role of these mucins is to stabilize the tear film, given that the gel-forming mucin constitutes the main component of the mucous layer, which is the innermost layer of the film (Watanabe H., 2002).
In the present study, we measured the clinical parameters of tear function and the changes in conjunctival goblet cell density GCD before and after LASIK procedure performed with a femtosecond laser. The goal of our study was to evaluate the effect of the femtosecond LASIK procedure on the tear function and stability.
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