ABSTRACT
AIM: To investigate the efficacy of epithelial-off accelerated corneal cross-linking(CXL)in the treatment of advanced keratoconus.METHODS: A retrospective study was performed on data collected from 32 patients(43 eyes)with advanced keratoconus who underwent epithelial-off accelerated CXL at Ningxia Eye Hospital from April 2020 to December 2021. Slit-lamp, intraocular pressure, uncorrected visual acuity(UCVA), corrected visual acuity, specular microscope, Pentacam and Corvis ST were tested before and at 1, 3 and 6mo after surgery. Preoperative and postoperative corneal condition, UCVA, best corrected visual acuity(BCVA)and the values of corneal endothelial, maximum keratometry(Kmax), thinnest corneal thickness(TCT), anterior and posterior surfaces of the cornea K1, K2, biomechanically corrected intraocular pressure(bIOP), applanation time 1(A1T), applanation length 1(A1L), applanation velocity 1(A1V), applanation time 2(A2T), applanation length 2(A2L), applanation velocity 2(A2V), highest concavity deformation amplitude(HCDA), radius at highest curvature(HCR), highest concavity peak distance(HCPD)and stiffness parameter at first applanation(SP-A1)were recorded.RESULTS: There were differences between UCVA(LogMAR; 1.06±0.49, 0.78±0.39)and BCVA(LogMAR; 0.48±0.34, 0.38±0.29)before and at 6mo after surgery(P<0.05), but there were no differences in corneal endothelial cells(2917.39±288.38 vs. 2959.19±336.27 cells/mm2, P=0.477). There were differences among Kmax, TCT, anterior surface K1 and K2 and posterior surface K1 before and after surgery(P<0.05), and all increased at 1mo after surgery then returned to preoperative level at 3mo after surgery, while there was no difference in the posterior K2. Furthermore, there were statistical significance in A1T, HCPD and SP-A1 before and after surgery(P<0.05), while there were no statistical significance in A1L, A1V,A2T, A2L, A2V, HCDA, HCR and bIOP(P>0.05).CONCLUSION: Epithelial-off accelerated CXL can prevent the progression of keratoconus within half year after surgery, and it has certain safety.
ABSTRACT
AIM:To evaluate the changes in corneal biomechanics of patients with moderate refractive error after receiving small-incision lenticule extraction(SMILE)and femtosecond laser-assisted laser in situ keratomileusis(FS-LASIK)using the corneal visualization Scheimpflug technology(Corvis ST).METHODS:Prospective cohort study. A total of 65 moderate myopia patients(65 eyes)who were scheduled to undergo refractive surgery at the Ophthalmic Refractive Surgery Center of the Ningxia Eye Hospital from November 2020 to November 2021 were included in the study, and there were 30 eyes in the SMILE group and 35 eyes in the FS-LASIK group. The changes in corneal biomechanical parameters, including integrated radius(IR), inverse concave radius(ICR), deformation amplitude ratio 2mm(DAR2), stiffness parameter at first applanation(SP-A1), ambrosio relational thickness(ARTh)and the central curvature radius at highest concavity(HC-Radius)were observed by Corvis ST between both groups preoperatively and 1 and 3mo postoperatively.RESULTS: There were no statistical significance in biomechanical parameters between two groups of patients 1 and 3mo postoperatively(P&#x003E;0.05). IR, ICR and DAR2 of each groups of patients 1 and 3mo postoperatively were significantly increased than those preoperatively, and SP-A1, ARTh and HC-Radius were significantly decreased than those preoperatively(all P&#x003C;0.05). The biomechanical parameters at 1mo and 3mo postoperatively showed no statistical significance(P&#x003E;0.05). In addition, a positive correlation was found between central corneal thickness(CCT)and ARTh and SP-A1 of the two groups of patients at 3mo postoperatively(FS-LASIK group: r=0.727, 0.819, SMLIE group: r=0.683, 0.434, all P&#x003C;0.05), while a negative correlation was found between CCT and IR and ICR at 3mo postoperatively.(FS-LASIK group: r=-0.697, -0.622, SMLIE group: r=-0.447, -0.491, all P&#x003C;0.05).CONCLUSION:For patients with moderate myopia, both SMILE and FS-LASIK can reduce corneal biomechanical stability. Both surgeries showed no significant differences in the effect on biomechanical, and the biomechanical has been stabilized at 1mo postoperatively. A correlation was found between postoperative CCT and ARTh, SP-A1, IR and ICR.