Outcomes of a New Trans-epithelial Photorefractive Keratectomy (Streamlight PRK) Compared to Conventional PRK Procedures

Not Applicable

Completed

• Conditions: Myopia ≤ -6 Diopters or Myopic Astigmatism ≤ -4 Diopters
• Interventions: Procedure: Photorefractive keratectomy (PRK)

• Registration Number: NCT04710082
• Lead Sponsor: Assiut University

Brief Summary

Photorefractive keratectomy (PRK) involves mechanical or alcohol assisted debridement of the epithelium that leads to potential basement membrane (BM) injury ,with resultant more significant haze and pain compared to laser assisted epithelial removal known as 2 step trans-epithelial PRK (PTK-PRK). Our study is focusing on comparing the outcomes of the conventional 2 step trans-epithelial PTK-PRK to the new single step trans-epithelial PRK (StreamLight PRK, Alcon lab, TX, USA).

Detailed Description

Photorefractive keratectomy (PRK) is nowadays one of the commonest refractive procedures in laser vision correction (LVC). PRK differs from laser in situ keratomileusis (LASIK) in that it's a flapless procedure involving the removal of corneal epithelium with different techniques including manual removal , alcohol assisted removal or excimer laser assisted removal with phototherapeutic keratectomy (PTK). Mechanical or alcohol assisted debridement of the epithelium may lead to potential basement membrane (BM) injury ,with resultant more significant haze and pain compared to laser assisted epithelial removal known as 2 step trans-epithelial PRK (PTK-PRK).

Single step trans-epithelial PRK allows removing the epithelium and stroma in a single step with a single ablation profile.

Previous studies paid particular attention for comparing the 2 step PTK-PRK procedure or the new single step PRK procedure to the conventional PRK procedures involving epithelial removal whether manual or alcohol assisted.

The aim of this study is to focus on comparing the different outcomes of the new single step Trans-epithelial PRK (StreamLight Technology) versus the routine 2 step PTK-PRK in terms of postoperative vision, epithelial healing, pain scoring and haze evaluation.

Study Timeline

• Study Start: 2020-06-01
• Study First Submitted: 2021-01-08
• Study First Submitted QC: 2021-01-12
• Study First Posted: 2021-01-14
• Primary Completion: 2021-06-30
• Study Completion: 2021-06-30
• Status Verified: 2021-07
• Last Update Submitted: 2021-07-19
• Last Update Posted: 2021-07-20

Recruitment & Eligibility

• Status: COMPLETED
• Sex: All
• Target Recruitment: 50

Inclusion Criteria

Candidates for Laser vision correction (LVC) with

1. Myopia up to -6 diopters
2. Myopic astigmatism up to -4 diopters
3. Corneal thinnest location ≥ 500 um and a residual stromal bed ≥ 300um.

• Exclusion criteria

  1. Patients not candidates for LVC.
  2. Hyperopic patients.
  3. Systemic disease that contraindicates LVC.
  4. Intra- or post-operative complications.

Exclusion Criteria

Not provided

Study & Design

• Study Type: INTERVENTIONAL
• Study Design: PARALLEL

Arm && Interventions

Group	Intervention	Description
Patients planned to undergo the new single step trans-epithelial (StreamLight) PRK.	Photorefractive keratectomy (PRK)	Patients planned to undergo: Epithelial removal and Excimer wavefront optimized Laser Vision Correction in a single step using the new StreamLight Technology.
Patients planned to undergo conventional 2 step trans-epithelial PTK-PRK	Photorefractive keratectomy (PRK)	Patients planned to undergo: 1. Epithelial removal using Phototherapeutic Keratectomy PTK as a separate step. 2. Laser Vision Correction using Excimer laser wavefront optimized technology.

Primary Outcome Measures

Name	Time	Method
Uncorrected distant visual acuity (UDVA)	6 months	Visual acuity measurement using Snellen's Acuity Chart and will be expressed as decimal notation
Postoperative Refraction (Spherical equivalent)	6 months	Measured by Topcon Auto-Keratorefractometer

Secondary Outcome Measures

Name	Time	Method
Postoperative Haze	3 months	Corneal Haze scoring using slit lamp bio-microscopy according to Fantes scoring system: 0: No haze, completely clear cornea; 0.5: Trace haze seen with careful oblique illumination; 1. Haze not interfering with visibility of fine iris details; 2. Mild obscuration of iris details; 3. Moderate obscuration of the iris and lens; 4. Complete opacification of the stroma in the area of the scar, anterior chamber is totally obscured
Epithelial healing duration	2 weeks	Time for the epithelium to heal reported in days after PRK procudre
Postoperative pain	1 week	Verbal Rating Scale(a series of words commonly used to describe pain (0: no pain, 1: mild pain, 2: moderate pain, 3: severe pain, 4: disabling pain)

Trial Locations

Locations (1)

TIBA eye center; 🇪🇬 Assiut, Egypt