Factors Affecting Changes In The Effective Optical Zone Following Hyperopic Small Incision Lenticule Extraction

To evaluate changes in the effective optical zone (EOZ) following hyperopic small incision lenticule extraction (SMILE) and investigate the factors affecting it.

Eye and ENT Hospital of Fudan University, Shanghai, China.

This study included 27 patients (31 eyes) who underwent hyperopic SMILE and were followed up for at least 6 months postoperatively. Changes in EOZ from the programmed optical (∆EOZ/POZ) and treatment (∆EOZ/PTZ) zones were assessed using a custom software program and compared between groups A (2.0-mm transition zone) and B (0.2-mm or without a transition zone) at both the early (within 1 month postoperatively) and late postoperative stages (after 6 months postoperatively). The effects of other related parameters were also explored.

The respective early and late EOZ diameters were 4.27 ± 0.20 and 4.04 ± 0.21 mm in group A and 3.48 ± 0.29 and 3.12 ± 0.49 mm in group B, respectively. ∆EOZ/POZ and ∆EOZ/PTZ were significantly larger at the late than the early postoperative stage in both groups (P < .001), with larger ∆EOZ/POZ values in group B than that in group A at both stages (P < .001). Similar ∆EOZ/PTZ values were observed in the two groups. After adjusting for the group effect, EOZ reduction was negatively associated with POZ at the late postoperative stage (∆EOZ/POZ: P = .043, β = –16.265; ∆EOZ/PTZ: P = .020, β = –16.589).

EOZ continues contracting after hyperopic SMILE. A larger transition zone and POZ would result in a larger EOZ.