Jiaxi Li,1,* Jing Zhen,2,* Ke Xie,2 Kaihua Yao,2 Ziyuan Liu,1 Xuemin Li1 

1Department of Ophthalmology, Peking University Third Hospital, Beijing, People’s Republic of China; 2Beijing Meiermu Hospital, Beijing, People’s Republic of China

*These authors contributed equally to this work

Correspondence: Ziyuan Liu; Xuemin Li, Department of Ophthalmology, Peking University Third Hospital, Number Forty-Nine North Garden Road Haidian District, Beijing, 100191, People’s Republic of China, Email ziyuanliu@126.com; lxmlxm66@sina.com

Background: To compare the postoperative visual quality of patients undergoing small-incision lenticule extraction (SMILE) with spherical trial lens intervals of 0.05D and 0.25D in preoperative manifest refraction.
Methods: The study included 196 eyes of 101 patients with 0.05D intervals to perform manifest refraction and 194 eyes of 98 patients with 0.25D intervals. Intraoperative lenticule thickness was compared in patients with different myopic grades. Postoperative examinations, including uncorrected distance visual acuity (UDVA) and manifest refraction results, were compared at 1-day, 1-week and 1-month follow-up.
Results: At the one-month follow-up, there was no significant difference in UDVA and spherical equivalent (SE) between the two groups (P=0.602 and 0.898, respectively). But the proportion of patients with a UDVA of more than 0.0 one month postoperatively was higher in the 0.05D intervals group (P=0.067). In patients with moderate myopia, the corneas with 0.05D interval manifest refraction had thinner maximum lenticule thickness compared with those in the control group (P=0.019).
Conclusion: Compared with the 0.25D interval group, patients performed manifest refraction with 0.05D spherical lens interval obtained equally good postoperative visual quality. The moderate myopia patients in the 0.05D interval group had thinner cornea cut during SMILE.

Keywords: small-incision lenticule extraction, manifest refraction, refractive surgery