A pilot study: LASEK with the Triple-A profile of a MEL 90 for mild and moderate myopia

Abstract

Background: To investigate the visual and refractive outcomes in patients with mild to moderate myopia after laser-assisted subepithelial keratectomy (LASEK) using the 500 Hz pulse rate of the Triple-A profile.

Methods: Thirty-six eyes of 20 patients (mean age, 27.5 ± 4.6 years) were included in this prospective, consecutive study. Uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), corneal topography, and corneal aberrations were measured preoperatively and 1 day, 1 week, 1, 3 and 6 months post-operation.

Results: At 1 week after surgery, UDVA was better than or equal to 20/25 in all eyes. At postoperative 6 months, the efficacy and safety index was 1.05 ± 0.13 and 1.12 ± 0.15, respectively; all eyes had a UDVA of 20/20 or better, and no eyes showed a loss in CDVA; 100% of the eyes were within ±1.00 D of the attempted spherical equivalent (SE) correction.

Conclusion: The postoperative results indicate that using the Triple-A ablation profile of the MEL 90 excimer laser with a 500 Hz pulse rate is a safe, efficient, and predictable method to correct mild to moderate myopia.

Keywords: LASEK; MEL 90; Myopia; Triple-A.

Fig. 1

The represented images showed the laser-assisted subepithelial keratectomy (LASEK) surgical procedures. The ablation center adjustment (a); the corneal epithelium was immersed in 20% alcohol (b); the epithelial flap was removed following immersion (c); the Corneal Bowman’s membrane and stroma were ablated with the MEL 90 excimer laser (d); the epithelial flap was repositioned after laser ablation (e); a bandage soft contact lens was applied (f)

Fig. 2

Visual outcomes after the MEL 90 and MEL 80 at 6 months: Cumulative percentage of eyes with preoperative corrected distance visual acuity (CDVA) and postoperative uncorrected distance visual acuity (UDVA) results (a&b), percentage of eyes with various changes in postoperative UDVA and preoperative CDVA (c), and percentage of eyes with various changes in CDVA (d)

Fig. 3

Scatterplot of the attempted versus achieved manifest spherical equivalent (SE) correction at 6 months after LASEK surgeries in both groups (a&b). Refractive outcomes at 6 months: Percentages of eyes within different diopter ranges of the intended correction in SE (c)

Fig. 4

Vector analysis for LASEK at 6 months after surgery in both groups. Percentages of eyes that achieved definite levels of astigmatism (a&b), and distribution of the angle of error (c)

Fig. 5

Changes in corneal aberrations pre-operation and at 6 months after surgery using the MEL 90 excimer laser. a Changes in anterior corneal aberrations (μm). b Changes in posterior corneal aberrations (μm). c Changes in total corneal aberrations (μm). ^* Less than 0.05, ^** less than 0.01