Abstract
Purpose :
The purpose of this study is to evaluate the corneal tissue interface quality with various refractive surgical procedure variables to aim for an improvement on visual recovery time with the ELITA Smooth Incision Lenticule Keratomileusis (SILK) procedure. It is hypothesized that ELITA SILK will have a thin disturbed interface (DI) thickness due to its biconvex shape, ultralow pulse energy, and small spot spacing.
Methods :
Total of 55 ex-vivo porcine eyes at 504 locations were assessed. ELITA SILK procedures with biconvex shape cut were conducted with 40nJ, 50nJ, 60nJ, 70nJ, and 80nJ anterior and posterior pulse energies, 65nJ ring and entry energy, -4 diopter manifest sphere, -1 diopter manifest cylinder, 180° manifest cylinder, and anterior depth of 110µm. ELITA flaps were conducted with 9.0mm diameter, 62nJ bed and side cut energy, and 110µm depth; iFS flaps were conducted with 9.0mm diameter, 0.7µJ bed and side cut energy, and 120µm depth. An HRT3 RCM confocal microscope (Heidelberg Engineering) volume scan (400x400µm field of view lens, 1.3µm depth increment) was used to capture images near the treatment location. The DI thickness for each volume scan was measured by determining the starting and ending depth of brighter images created by excess light reflected from the corneal interface surface roughness. A vacuum-based eye holder was developed to hold the eyes orthogonal to the laser pathway and Siccaforte eye gel (Carbomer 0.2%) was used to create a gel bridge between the eye and the imaging surface.
Results :
The DI thickness for ELITA SILK at 40nJ is 25 ± 3µm (mean ± SD), ELITA flap at 62nJ is 24 ± 2µm (mean ± SD), and iFS flap at 0.7µJ is 32 ± 3µm (mean ± SD). As pulse energy increases, the final SILK DI thickness increases by 0.4µm/nJ (p = 0.001). Mechanical lenticular dissection increases lenticular surface DI thickness by 6µm or 37% (p < 0.001).
Conclusions :
Our study revealed a superior corneal interface quality with the ELITA SILK with its biconvex shape cut. The disturbed interface with ELITA SILK is very thin (25µm) and offers an opportunity for improvement.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.