Characteristics of straylight after small incision lenticule extraction versus femtosecond laser-assisted laser in situ keratomileusis

Background

Small incision lenticule extraction (SMILE) was a new procedure which is mini-invasion and flapless,but few attentions were paid to the visual quality after SMILE.To understand the changes of intraocular straylight after SMILE is of important significance for the assession of the visual quality after the procedure.

Objective

This study was to compare the characteristic of straylight between SMILE and femtosecond laser assisted laser in situ keratomileusis (FS-LAISK) after surgery.

Methods

A retrospective study was designed.Written informed consent was obtained from each patient prior to accepting the surgery.One hundred and twenty-seven eyes of 68 patients with myopia and myopic astigmatism were included in Tianjin Eye Hospital from January 2011 to July 2013.SMILE was performed on 64 eyes of 35 patients and FS-LASIK was carried out in 63 eyes of 33 patients at the same period.Stray light was detected with C-Quant stray light meter before and 1 week,1 month and 6 months after surgery.The changes of stray light values following the surgery were compared between the two groups,and the correlations between postoperative stray light values with operative parameters were analyzed.

Results

The mean stray light values were (1.03±0.19)D and (0.95±0.16)D at 1 week and 1 month after surgery,which were higher than (0.88±0.18)D at preoperation in the FS-LASIK group (P=0.000,0.012).The stray light values were (0.98±0.16),(0.95±0.14) and (0.94±0.16)D at 1 week,1 month or 6 months after surgery,and no statistically significant differences were found in comparison with (0.91±0.15)D in preoperation in the SMILE group (all at P>0.05).No significant intergroup difference was seen in the stray light values (F_group=0.077,P=0.781).The stray light differences of various time points after surgery and before surgery were increased in the FS-LASIK group compared with SMILE group (F_group=14.798,P<0.001),with the significant difference in postoperative 1 week between the two groups (P<0.01).The negative correlations were found between stray light values at 1 week,1 month and 6 months after SMILE with the lenticule thickness/central corneal thickness (CCT) (R²=0.123,0.145,0.098,all at P<0.05) or between stray light change.

Conclusions

Intraocular stray light appears less change in operative eyes after SMILE. However, intraocular stray light increases in the eyes received FS-LASIK, especially at early stage after operation. The stray light shifts return to normal with the lapse of postoperative time.

Straylight; Myopia, myopia astigmatism/surgery; Visual quality; Small incision lenticule extraction; Femtosecond laser assisted laser in situ keratomileusis