Effects of different side-cut angles on ocular surface recovery after FS-LASIKOA

●AIM:To compare the effects of different side-cut angles on postoperative ocular surface recovery after femtosecond laser-assisted in situ keratomileusis(FS-LASIK).●METHODS:The prospective and randomized study enrolled 99 patients(198 eyes)with ametropia who underwent FS-LASIK in the Eye Institute at the Affiliated Hospital of Nantong University from September 2021 to December 2022.The patients were categorized into the 45°,90°,and 135°side-cut angle groups.Preoperatively and at 10d,1mo,and 6mo after surgery,patients in the three groups had their visual acuity,corneal flap edge scar,corneal region sensation,dry eye-related index changes,and nerve fiber repair at the corneal flap margin compared and analyzed.●RESULTS:In the groups with 45°,90°,and 135°sidecut angles,56,58,and 62 eyes,respectively,finished the 6-month follow-up.The incidence of flap edge healing scar was the lowest in the 90°side-cut angle group(74.1%).At 10d postoperatively,corneal sensation at all sites decreased significantly compared with preoperative corneal sensation in the three groups(P<0.05),while patients in the 90°sidecut angle group had the highest sensation among the three groups.After surgery,the Ocular Surface Disease Index(OSDI)scores of the three groups showed a substantial rise 10d later,a reduction 1mo later,and a continued increase beyond preoperative values 6mo later(P<0.05).The 90°side-cut angle group had the lowest OSDI score at each follow-up time.At each time point after surgery,the number of eyes repaired by corneal flap nerves in the scarless group was higher than that in the scarred group(P<0.05),and the corneal flap nerve growth was relatively fast in the scarless area.●CONCLUSION:Different side-cut angles in FS-LASIK may have different effects on the postoperative ocular surface recovery.The 90°side-cut angle has a low incidence of corneal flap scar,the highest corneal sensation in the early postoperative period,and the lowest subjective dry eye symptom scores at each postoperative follow-up time.Therefore,the selection of a 90°side-cut angle for the FS-LASIK corneal flap may help patients to recover the ocular surface after surgery.