Visual and Refractive Outcomes Following Stream Light Photorefractive Keratectomy (55μm Epithelial Removal) Versus Conventional Photorefractive Keratectomy

Visual and Refractive Outcomes Following Stream Light Photorefractive Keratectomy (55μm Epithelial Removal) Versus Conventional Photorefractive Keratectomy

Photorefractive keratectomy (PRK) is a well-established corneal refractive surgery that involves epithelial removal followed by stromal ablation to correct myopia, hyperopia, and astigmatism. The method of epithelial removal in PRK significantly impacts healing, pain levels, and visual outcomes.

Trans-epithelial PRK (StreamLight) performed on the EX500 excimer laser platform removes the epithelium and reshapes the corneal stroma in a single laser-guided step, potentially reducing tissue manipulation and enhancing epithelial healing. In contrast, manual epithelial removal PRK involves mechanical debridement, with epithelial removal depth being manually controlled. The variability of epithelial thickness in StreamLight PRK may influence visual outcomes, whereas in manual PRK, a fixed epithelial removal depth of 55 microns provides a standardized approach.

This study aimed to compare the visual and refractive outcomes of StreamLight PRK versus manual PRK with fixed epithelial removal.

Type of the study: Retrospective cross-sectional study

• Study Setting: Alforsan Eye Centre

• Study subjects:

  a. Inclusion criteria:

  • Patients aged 18-40 years.
  • Myopia up to -6.00 D and astigmatism up to -3.00 D.
  • Stable refraction for at least one year.
  • No history of ocular surgery or corneal pathology. b. Exclusion criteria:
  • Presence of keratoconus or suspected corneal ectasia.
  • Severe dry eye disease or significant ocular surface disease.
  • History of autoimmune disease or systemic conditions affecting wound healing.
  • Prior herpetic eye disease. c. Sample Size Calculation: A sample size calculation will be performed to ensure adequate statistical power. Anticipated enrollment: [e.g., 50 eyes per group] based on previous PRK outcome studies (Marshall et al., 2018).

• Study tools (in detail, e.g., lab methods, instruments,steps, chemicals, …):

  • Alcon Wavelight EX500 excimer laser (Alcon Laboratories, Fort Worth, TX, USA)
  • Wavelight Oculyzer II Am Wolfsmantel 5, Erlangen, Germany
  • Autorefractor KR-8900 (Topcon, Tokyo, Japan)

Inclusion Criteria:

• Patients aged 18-40 years.
• Myopia up to -6.00 D and astigmatism up to -3.00 D.
• Stable refraction for at least one year.
• No history of ocular surgery or corneal pathology.

Exclusion Criteria:

• Presence of keratoconus or suspected corneal ectasia.
• Severe dry eye disease or significant ocular surface disease.
• History of autoimmune disease or systemic conditions affecting wound healing.
• Prior herpetic eye disease.