Pain, wound healing and refractive comparison of mechanical and transepithelial debridement in photorefractive keratectomy for myopia: Results of 1 year follow-up

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Abstract

Purpose

To compare the efficacy, safety and postoperative pain of mechanical versus transepithelial photorefractive keratectomy (PRK) techniques.

Setting

Cornea and refractive surgery subspecialty.

Design

Prospective clinical trial.

Methods

This prospective comparative study included 84 eyes of 42 patients with myopia who received mechanical PRK (m-PRK) in 1 eye and transepithelial PRK (t-PRK) in the contralateral eye. The mean patient age was 28.5 ± 6.3 years (range 20–46 years). Postoperative uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), manifest refractions, postoperative epithelial healing time, surgical time, postoperative pain rating and corneal haze were recorded.

Results

At week 1, statistically the UDVA was significantly better in the t-PRK eyes; however, at 3 months, similar refractive stability was achieved in both groups. The mean spherical equivalent (SE) decreased from −2.44 ± 1.00 D (m-PRK eyes) and −2.88 ± 1.24 D (t-PRK eyes) at baseline to −0.19 ± 0.38 D and −0.30 ± 0.40 D, respectively, after 1 year. Surgical time was 98.6 ± 9.8 s in m-PRK eyes and 58.0 ± 6.4 s in t-PRK eyes. On postoperative days 1 and 3, using the global assessment rating, 81% of mPRK eyes that had pain, reported more pain than that reported for the tPRK eyes. In addition, m-PRK treated eyes demonstrated higher mean pain scores based on the 11-point numerical rating scale and Visual Analogue Scale (VAS). The mean time to complete epithelial healing was 2.19 ± 0.39 days (t-PRK) and 3.76 ± 0.43 days (m-PRK).

Conclusion

t-PRK for mild-to-moderate myopia was more comfortable than conventional m-PRK; patients had less pain, and faster healing time.

Introduction

The advents of excimer LASER refractive surgery heralded a new era in ophthalmic practice [1], [2]. Evolution of both LASERs and surgical techniques has resulted in millions of patients having undergone LASER-based procedures [3]. Although LASER in situ keratomileusis (LASIK) is the most commonly performed LASER refractive corneal surgery in the world, surface ablation with photorefractive keratectomy (PRK) may be a safer option [4], [5], [6], [7], [8], [9], [10], [11]. Flap complications and a higher risk of iatrogenic keratectasia in association with LASIK have driven the increased popularity of PRK [12], [13], [14], [15], [16], [17], [18], [19], [20], [21], [22]. In PRK, refractive surgical ablation is performed on the corneal surface after epithelial debridement. Postoperative pain and the potentially higher grade of corneal haze after PRK limits its usefulness and acceptance [23]. Several techniques of epithelial debridement have been attempted with PRK surgery, including mechanical debridement, LASER transepithelial ablation, a rotating brush and alcohol debridement [23]. Previous studies document that all of the epithelial debridement methods with PRK are effective procedures for the surgical correction of myopia [24], [25], [26]. In transepithelial PRK, the excimer LASER is used to ablate the epithelium, followed by ablating the underlying stroma [27]. For this purpose, several excimer LASER devices provide surgeons with the option of performing both surface ablation and LASER treatment in eyes.

In this study we evaluated and compared the efficacy, safety and postoperative pain evaluation of mechanical and LASER-assisted epithelial debridement techniques of PRK for low-to-moderate myopia.

Section snippets

Materials and methods

This prospective comparative study included 84 eyes of 42 patients with myopia who had mechanical PRK (m-PRK) in 1 eye and transepithelial PRK (t-PRK) in the contralateral eye performed by two surgeons (OFY, AD). One eye in each patient was randomly chosen to have m-PRK, and the other eye had t-PRK. Patients were told that each eye would have a different epithelial debridement procedure but did not know which eye had m-PRK and which had t-PRK. Written informed consent was obtained from all

Results

The mean age of the 24 men and 18 women was 28.5 ± 6.2 years (range 20–46 years). The preoperative mean SE was −2.44 ± 1.00 D (range −1.00 to −6.00 D) for m-PRK and −2.88 ± 1.24 D (range −1.00 to −6.00 D) for t-PRK. All eyes had refractive astigmatism less than −1.00 D. The mean refractive cylindrical value was −0.43 ± 0.34 D for the m-PRK and −0.33 ± 0.35 D for the t-PRK.

The mean preoperative keratometry, UDVA and CDVA were 43.59 ± 1.67 D (range 38.9–47.35 D), 0.85 ± 0.37 (range 0.30–1.70 D, LogMAR) and −0.01 ± 0.03

Discussion

The t-PRK was previously defined as a complementary treatment modality after keratoplasty, radial keratotomy (RK), and post LASIK surgery [32], [33], [34]. The idea of considering t-PRK as a main treatment option was proposed in 1998 [35]. However, the idea was not proven until 2007 [36], [37]. In 2007, t-PRK treatment provided better results than LASIK, LASEK, and epi-LASIK surgeries, phototherapeutic keratectomy mode for epithelial debridement and stromal ablation mode were used for the

What was known

  • LASIK is the most commonly performed LASER refractive corneal surgery in the world; surface ablation with PRK may be a safer option.

  • In PRK, refractive surgical ablation is performed on the corneal surface after epithelial debridement; several techniques have been tried with PRK, including mechanical debridement, LASER transepithelial ablation, a rotating brush and alcohol debridement.

What this paper adds

  • In the early postoperative days after PRK surgery, there were significant differences in terms of pain, epithelial healing time and postoperative haze in the transepithelial PRK debridement group. The pain scores were lower, and the epithelial healing time was shorter, the debridement phase causes less haze formation which provided higher patient comfort after the surgery.

Funding

This prospective study was not supported by any of the company. None of the authors has financial or proprietary interests in any material or method mentioned. This data has not been previously published.

Authors contribution

Involved in design and conduct of the study (OFY, AD, UC); preparation and review of the study (UC); data collection (UC, BC); and statistical analysis (UC).

Conflicts of interest

The authors declare that there are no conflicts of interest.

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