Abstract
Purpose :
The purpose of this study is to evaluate the flap performance of a new femtosecond laser system (NFS) for corneal refractive surgeries. To achieve precision and minimal tissue adhesion, the NFS is designed with ultralow pulse energy, contiguous spots pattern, and a submicron Auto-Z depth calibration.
Methods :
50 ex-vivo porcine eyes were used for flap thickness measurements and 6 in-vivo rabbit eyes were used for flap side cut angle measurements. The NFS porcine flap was programmed with 90 µm thickness, 110° side cut angle, and 9.0 mm diameter. Post treatment, the flap was lifted, excised, transferred onto a glass slide and a cover glass slide was placed. A standard micrometer (Mitutoyo 406-350-30) and caliper (Mitutoyo) were used to measure flap thickness and diameter, respectively. Corrected flap thickness was calculated from the measured flap thickness and diameters. Programmed flap side cut angles ranging from 30° to 150° with 110 µm thickness were performed on in-vivo rabbit eyes and measured with RTVue XR Avanti OCT system (OptoVue Inc). Flap lift and surface quality were assessed by a subject matter expert (SME) on a scale of 1-4 (1: no lift, 2: some adhesions, 3: little adhesions, 4: no adhesions).
Results :
All flap cuts were completed successfully. The measured flap thickness on ex-vivo porcine eyes was 95.16 ± 3.32 µm (SD) and corrected was 96.74 ± 2.93 µm (SD); data range is acceptable. For the in-vivo rabbit eyes, OCT measurements of side cut angles and flap thickness are summarized in Table 1. The average thickness on rabbit eyes was 109 µm (range 100-113 μm) and all measured side cut angles were within ±8° of the programmed angles, demonstrating reliable performance. All the flaps received a SME score of 4 for side cut quality, and an average SME score of 3.67 for bed cut separation quality, with little to no adhesions.
Conclusions :
The new femtosecond laser system produced very consistent flap thicknesses (SD = 2.93 μm), allowing surgeons to make 90 μm thin flaps reliably. All side cut angles were within the design tolerance; NFS produced flap sidecut and bed surface of satisfactory quality.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.