Comparison Of The Outcomes Of Single-Step Transepithelial Photorefractive Keratectomy (Trans-Prk) Using The Streamlight Software With And Without Epithelial Thickness Personalization.

To compare the refractive, aberrometric, and densitometric results of single-step transepithelial photorefractive keratectomy performed with epithelial thickness adjustment (ADJ group) and without epithelial thickness adjustment (No-ADJ group) using the StreamLight software of WaveLight EX500 laser excimer (Alcon Laboratories, Inc., Fort Worth, TX).

Miranza Begitek. Donostia - San Sebastián, Spain.

This prospective, observational case series study comprised 108 eyes (52 eyes in the ADJ group and 56 eyes in the No-ADJ group) of 108 patients undergoing Trans-PRK with and without epithelial thickness personalization. Visual acuity, refraction, corneal higher-order aberrations (HOA) and corneal densitometry (CD) were measured at the pre-operative and 6 months postoperative visit. Pentacam AXL was used to obtain the corneal measurements. CD was measured in various ring-shaped zones (0-2mm; 2-6mm; 6-10mm;10-12mm) for different corneal depths (first anterior 120µm, center, posterior 60 µm and total corneal thickness). HOA were measured for corneal front surface and total cornea at 6 mm area of analysis.

The mean ablation of epithelial thickness in ADJ group was 54.81 ± 3.56 µm vs. 55 µm in the No-ADJ group (p=0.470). There were no statistical differences in the preoperative sphere, spherical equivalent (SE), and high order aberrations (HOA) values between the two groups (ADJ vs. No-ADJ). At 6 months postoperatively, there were no statistical differences (p>0.05) in CF-HOA and Cornea-HOA when comparing between ADJ group and No-ADJ group. At 6 months postoperatively, CD was reduced statistically significantly in the anterior depth in ADJ group in 0-2, 2-6, and 6-10 mm rings. However, in group No-ADJ group 6–10 mm ring in the anterior and posterior depth were reduced in a statistically significant way (p<0.05).

Both techniques seemed to be safe and effective in refractive surgery and demonstrated comparable visual, refractive outcomes and aberrometric outcomes. Adjusting the laser ablation depth according to the corneal epithelium thickness didn´t improve the refractive results over using an standard average epithelium depth