Comparison Of Corneal Densitometry In The Early Postoperative Periods Between Transepithelial Photorefractive Keratectomy(TransPRK),Femtosecond-assisted Laser In-Situ Keratomileusis(FS-LASIK) And Small-Incision Lenticule Extraction(SMILE)

Purpose: The aim of this study was to evaluate the corneal densitometry changes after Transepithelial photorefractive keratectomy(Trans PRK),Femtosecond-assisted laser in-situ keratomileusis(FS-LASIK)and Small-incision Lenticule Extraction(SMILE)in the early postoperative periods and to compare these changes across the three widely used surgical techniques.Methods: This retrospective clinical study selected a total of 256 myopic patients who underwent corneal refractive surgery in Joint Shantou International Eye Center(JSIEC),including 77 patients in Trans PRK group,78 patients in FS-LASIK group and 90 patients in SMILE group.All participants underwent an exhaustive eye examination including visual acuity,refractive status and corneal densitometry before and 1month,3 months after surgery.Corneal densitometry was measured using an Oculus Pentacam system.Corneal densitometry was evaluated at 3 optically relevant,concentric radial zones(0–2 mm,2–6 mm,and 0–6 mm annulus)around the corneal apex and at 3 different anatomical corneal layers(anterior120um,central,and posterior60um).Results: There were no significant differences in uncorrected visual acuity(UCVA),corrected visual acuity(BCVA),spherical diopter,cylindrical diopter,SE and corneal densitometry(all corneal layers)among the 3 groups at 1 month after operation(P>0.05).At 3 months after the surgery,there was no significant difference in UCVA,BCVA,cylindrical diopter and SE between the 3 groups,spherical diopter values were significantly lower in SMILE the group than in the FS-LASIK group(P<0.05).Threemonth postoperative corneal densitometry showed no significant differences between the 3 groups for all examined layers and 0–2 mm,2–6 mm and 0–6 mm annulus.At 6–10 mm annulus,the corneal densitometry of FS-LASIK group was higher than that of SMILE group(P = 0.028).After the 3 operations,the corneal densitometry(all corneal layers)at 0–10mm annulus showed no significant change compared to preoperative values(P>0.05).Conclusion: The visual acuity and refractive status of Trans PRK,FS-LASIK and SMILE were similar at 1 and 3 months after operation.The corneal densitometry of FSLASIK group was higher than that of SMILE group at 6–10 mm annulus at 3 months after operation.There were no statistically significant differences in postoperative corneal densitometry after the 3 surgery.