The goal of this interventional comparative study is to assess the efficacy and safety of a novel regimen of preservative-free unit-dose topical anesthetics for controlling early postoperative pain following single-step transepithelial PRK surgery.

The main research questions to answer are:

• Question 1: Are topical anesthetics effective in reducing post-PRK pain?
• Question 2: Are short-term topical anesthetics toxic to the cornea?
• Question 3: How to prevent abuse of topical anesthetics by patients at home?

Participants were planned to undergo a bilateral single-step transepithelial PRK surgery to correct their refractive errors and received a standard post-PRK treatment regimen for both eyes. Additionally, one eye was offered a preservative-free topical anesthetic as an experimental group and the other eye was offered a preservative-free artificial tear as a control group.

Photorefractive keratectomy (PRK) is a well-established surface ablation procedure for correction of refractive errors which involves the removal of corneal epithelium in a large diameter usually more than 6 mm followed by stromal ablation.

Early postoperative pain within the first few days after surgery is one of the commonest complications reported after PRK. The classic postoperative treatment includes the prescription of topical antibiotics and frequent preservative-free lubricants to accelerate epithelial healing.

The current treatment regimens also includes topical steroids, topical non-steroidal anti-inflammatory drugs (NSAID) and oral NSAID to reduce inflammation and post-PRK pain.

Earlier studies suggested that topical anesthetics in diluted concentrations and fractional doses didn't delay corneal epithelial regeneration after PRK but their use didn't gain popularity because of problems with topical formulation, stability and preservation.

Inclusion Criteria:

Patients who are candidate for PRK surgery with

1. Myopia up to - 6 diopters or myopic astigmatism up to - 4 diopters.
2. Corneal thinnest pachymetry of 500 µm
3. Residual stromal bed more than 350 µm after epithelial ablation.

Exclusion Criteria:

Patients with

1. Corneal scars or dry eye disease,
2. Past ocular surgery,
3. History of contact lens wear,
4. Systemic diseases such as diabetes mellitus and autoimmune diseases,
5. History of oral analgesics abuse.