Einfluss unterschiedlicher Ablationsfrequenzen auf die klinischen Ergebnisse bei photorefraktiver Keratektomie unter Verwendung derselben Excimer-Laser-Plattform: Ein kontralateraler Vergleich

Abstract

The objective of this study was to evaluate postoperative clinical outcomes of photorefractive keratectomy (PRK) using different ablation frequencies. In this prospective, contralateral eye study, 56 eyes of 28 patients with myopia or myopic astigmatism were included. PRK was performed using the MEL90 excimer laser system (Carl Zeiss Meditec, Germany). One eye of each patient was treated with a repetition rate of 250 Hz, while the other one was treated with a repetition rate of 500 Hz. The treatment pattern in the 250 Hz and 500 Hz group only differed in terms of ablation frequency; there was no difference in laser pulse energy, spot size or ablation profile. Postoperative follow-ups were at 3 and 7 days and 1, 3 and 6 months. The following parameters were assessed: Uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), higher-order aberrations (HOAs), corneal re-epithelisation time and corneal haze. Ablation depth was proportional to laser pulse counts at both frequencies. At 6 months, 100.0% of the eyes in the 250 Hz group and 96.4% in the 500 Hz group had a UDVA of 0.00 logMAR or better; 100% of the eyes in both groups were within ± 1.00D of the attempted correction. All eyes had a postoperative CDVA of 0.00 logMAR or better. There was no difference between the groups in postoperative HOAs, corneal re-epithelisation time or corneal haze. Photorefractive keratectomy with a repetition rate of 250 Hz and 500 Hz showed comparable efficacy, safety and predictability in the correction of myopia. There were no significant complications due to the high repetition rate, such as postsurgical corneal haze.

Comparison of refractive outcomes after photorefractive keratectomy with different optical zones using Mel 90 excimer laser

“…In this study, we performed PRK using the Mel 90 excimer laser with the Triple-A profile which is improved from previous ASA and TSA profiles in that it has better error compensation function and target asphericity control, which minimizes ablation depth, adjusts for spherical aberration and prevents myopic regression [ 39 ]. The surgeon can also choose a frequency up to 500 Hz across the surgery in Mel 90 excimer laser, which enables faster ablation time for correction [ 39 , 40 ]. Thus, clinical outcomes after PRK with the same optical zone size can differ according to which excimer laser used, and it therefore seems inappropriate to compare this study with clinical data from studies that used the previous version of the excimer laser for PRK in the same way.…”

Clinical Evaluation of LASEK for High Myopia Correction between the Triple-A Profile and the Zyoptix Tissue Saving Profile

“…Chen et al found that the Triple-A profile with a frequency setting of 500 Hz was safe, efficient, and predictable for the correction of mild-to-moderate myopia [6]. Tandogan et al also found that ablation frequency was not a risk factor of haze after surgery [7]. However, the effect of Triple-A profile with a frequency setting of 500 Hz for the correction of high myopia remains unknown.…”

Flap Thickness and the Risk of Complications in Mechanical Microkeratome and Femtosecond Laser In Situ Keratomileusis: A Literature Review and Statistical Analysis

“…Since introducing excimer lasers for refractive surgery, several million people have been successfully treated to decrease or eliminate their dependency on glasses or contact lenses to correct their ametropia [ 1 ]. Surface ablation procedures, such as photorefractive keratectomy (PRK) or laser epithelial keratomileusis (LASEK) and epi-LASIK, can be used very effectively to correct ametropia [ 2 ], and the risk for the development of keratectasia in uncompromised corneas is low [ 3 ]. However, patients’ visual acuity recovery is rather slow, and patients suffer from quite severe pain in the postoperative period.…”