Comparison of optical zone decentration and visual quality after SMILE surgery with different ablation centers

Abstract

AIM: To study the postoperative optical zone decentration and visual quality by taking visual axis corneal reflect point(VACRP)and corneal vertex(CV)as the ablation center, exploring the femtosecond laser small incision lenticule extraction(SMILE).METHODS: Prospective randomized controlled trial. Totally 70 myopic patients(140 eyes)who underwent SMILE surgery in our hospital from May to June 2020 were randomly divided into two groups, 68 eyes of 34 cases took the VACRP as the ablation center(VACRP group), and 72 eyes of 36 cases took the CV as the ablation center(CV group). The visual acuity, refractive diopter, offset from corneal ablation center, and high-order corneal aberrations were observed before and 3mo after surgery. RESULTS: Three months after operation, there was no difference in uncorrected visual acuity, best corrected visual acuity and refractive diopter between the two groups(P>0.05). The ablation center deviation in CV group(0.20±0.13mm)was less than that in VACRP group(0.27±0.14mm, P<0.01). The total corneal high-order aberration(totHOA), spherical aberration(totZ40), vertical coma(totZ3-1)and horizontal coma(totZ31)in CV group were lower than VACRP group(P<0.05). Three months after operation, the totHOA, total high-order aberration change(ΔtotHOA), totZ40, totZ3-1 in VACRP group were correlated with ablation center deviation(r=0.470, 0.486, 0.254, -0.366, P<0.001, =0.001, 0.037, 0.002), totZ31 in CV group was correlated with the ablation center deviation(r=-0.352, P=0.002).CONCLUSION: SMILE surgery can obtain satisfactory uncorrected visual acuity and the same level of refractive diopter with the VACRP and the CV as the ablation center, but taking the CV as the ablation center can reduce the postoperative decentration and high-order corneal aberrations and obtain better visual quality.

Keywords

• femtosecond laser small incision lenticule extraction
• ablation center
• visual axis corneal reflect point
• corneal vertex
• visual quality