Optical Zone Centration Accuracy After Lenticule Extraction With Correction Of Pupil Offset Using Atos And Comparison To Trans-Prk.

Conventional SMILE surgery relies on the subjective adjustment of the surgeon to center the laser irradiation, which can lead to off-centering. SMILE surgery using Schwind's ATOS has a pupil offset correction function and an eye tracking device linked to Sirius, which allows the laser irradiation center to be set in advance according to the patient's visual axis. This study aims to analyze the accuracy of the center of laser irradiation when SMILE surgery is performed by correcting the center axis based on the offset value determined by preoperative examination, compared to the surgical results of conventional excimer laser.

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50 eyes underwent Trans-PRK surgery and 50 eyes underwent SMILE surgery with ATOS, using Pentacam and Sirius to determine preoperative pupil offset values so that the laser was centered on the optic axis. 

The degree of de-centralization of the treatment area at 1 month after surgery was determined by measuring the distance between the corneal vertex (0, 0) and the center of the horizontal and vertical axis of the treatment area in x, y coordinates using the Sirius device, and the distribution of the preoperative offset value and the distribution of the center axis of the actual postoperative laser irradiation were analyzed using distribution plots.

The mean centration offset was 0.20±0.11 mm in the SMILE group and 0.17±0.10 mm in the Trans-PRK group, with no statistically significant difference between the two groups. All patients (100%) in both groups had centration offset within 0.30 mm.

Unlike previous SMILE surgeries, SMILE surgery using Atos reflects the patient's offset value determined by various methods, and since the offset value can be set before surgery or corrected during surgery, laser irradiation can be performed on the center axis accurately, preventing side effects such as de-centration and increased hyperopia. In addition, unlike the existing Amaris excimer laser, the offset value linked to Sirius can be corrected intraoperatively, which is expected to further minimize the central axis setting error when reflected using multiple offset value analysis devices.