Features of Femtosecond Correction of High Myopia through Small Access

Abstract

Aim. To modify the calculated parameters of the lenticle extraction refractive surgery through a small access (SMILE), evaluate its safety and clinical efficacy in correcting high myopia.Materials and methods. 34 patients (68 eyes) underwent surgery by a modified SMILE technology under local anesthesia. In all cases, the patients had a high degree of myopia, in 37 % in combination with astigmatism.Uncorrected visual acuity before surgery averaged 0.05 ± 0.11, best corrected visual acuity of 0.94 ± 0.1, the pre-operative spherical refraction component was –7.23 ± 0.75, the cylindrical component was –0.48 ± 0.59.During the operation, to obtain the maximum possible refraction result using the proposed method, the standard operation parameters were changed: the corneal flap thickness was reduced to 100 μm, the neural optical layer by 5 μm, the diameter of the optical zone depended on the residual cornea thickness, which should exceed 280–290 μm. Corneal access was increased by 15–20 degrees.Results. The next day after surgery, monocular uncorrected visual acuity in distance in 73 % of patients was 0.8 or higher, and in 41 % of cases it was equal to or exceeded 1.0. The spherical equivalent on the first day after surgery had a slight hypermetropic shift, which was completely leveled by the year of follow-up. During the surgical intervention and in the postoperative period, no complications were noted.Conclusion. Using the proposed algorithm for calculating the refractive effect of the operation SMILE with a high degree of myopia allows obtaining a high refractive effect and avoiding possible complications.

Keywords

• femtosecond surgery
• smile
• high myopia