Clinical Analysis on Correction of Myopia and Myopic Astigmatism with Femtosecond Lenticule Extraction

Objective To evaluate the clinical outcome of femtosecond lenticule extraction(FLEx) in treating myopia and myopic astigmatism. Methods In this prospective study,30 eyes underwent femtosecond laserassisted laser in situ keratomileusis(FS-LASIK),where all flaps were created with the VisuMax femtosecond system followed by refractive treatment with MEL 80 excimer laser,and 30 eyes underwent femtosecond lenticule extraction(FLEx),where a flap and a refractive lenticule of intrastromal corneal tissue were simultaneously cut with the VisuMax femtosecond system. The followup lasted for six months when uncorrected visual acuity(UCVA),best spectacle-corrected visual acuity(BSCVA),objective and manifest refractions,higher-order aberrations(HOAs),contrast sensitivity function(CSF) curves were gathered and analyzed one week,one month,three months,and six months after surgery respectively. Results There were no statistically significant differences both in mean age and preoperative mean refraction between FLEx group and FS-LASIK group(P 0. 05). No complications occurred during the surgery or the postoperative period in both groups. At 6 months postoperatively,of the 30 eyes treated with FLEx,96. 7% were within ± 0. 75 D of intended correction,93. 3% had an UCVA of 4. 9(logMAR) or better,the mean UCVA was(4. 99 ±0. 13),80. 0% remained unchanged,13. 3% gained one line,3. 3% gained two lines of BSCVA,and 3. 3% lost one line of BSCVA. Of the 30 eyes treated with FS-LASIK,90. 0% were within ± 0. 75 D of intended correction,86. 7% had an UCVA of 4. 9(logMAR) or better,the mean UCVA was(4. 98 ± 0. 12),83. 3% remained unchanged, 6. 7% gained one line,6. 7% gained two lines of BSCVA,and 3. 3% lost one line of BSCVA. No eye lost 2 or more lines of BSCVA in both groups. With regard to the changes of spherical equivalent(SE) from 1 week to 6 months after surgery,the mean SE after FLEx changed from(+ 0. 25 ± 0. 79) D to(0. 05 ± 0. 56) D,and after FS-LASIK from(+ 0. 72 ± 0. 92) D to(0. 15 ± 0. 65) D. The mean change was 0. 30 D in FLEx treated eyes(P 0. 05),and 0. 87 D in FS-LASIK treated eyes(P 0. 01),demonstrating the results of FLEx were more stable than those of FS-LASIK. For a 6 mm pupil,the root mean square(RMS) values of total HOAs and spherical aberrations after FLEx were significantly less than those after FS-LASIK(P 0. 01). In night environment(for a 5 mm pupil size condition),the CSF values for FLEx treated eyes were higher than those for the FS-LASIK treated eyes at 1. 5,3,6,12 and 18 cpd space frequency(P 0. 01).Conclusions FLEx is a safe,effective,and predictable procedure for the treatment of myopia and myopic astigmatism. FLEx features more stable refractive results,less induction of HOAs and better contrast sensitivity than the FSLASIK.