COVID-19 is an emerging, rapidly evolving situation.
Get the latest public health information from CDC:

Get the latest research information from NIH: Menu

Visual Outcomes of Topography Guided Photorefractive Keratectomy (PRK) for Treatment of Patients With Irregular Cornea

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details. Identifier: NCT03140046
Recruitment Status : Completed
First Posted : May 4, 2017
Last Update Posted : May 11, 2020
Information provided by (Responsible Party):
Ahmed Abdelsamee Mohammed, Assiut University

Brief Summary:

Irregular astigmatism is one of the most serious and frequent complications of corneal refractive surgery and one of the worst sequelae of other forms of corneal surgery . It is also considered as one of common, serious complications of corneal injuries .

Spectacle correction is usually not useful in the correction of corneal irregular astigmatism. Contact lenses represent a good alternative, but their adaptation and stability are limited by the irregular corneal surface and patient discomfort.

In recent years, advancements in laser technology have offered better tools for dealing with irregular astigmatism with finding new surgical methods to improve corneal regularity for the correction of irregular astigmatism.

Topography-linked excimer laser is a potentially effective technique in the treatment of irregular astigmatism after keratoplasty . In fact, customized ablation was shown to be an effective means of treatment of irregular astigmatism due to different etiologies Such as corneal Injuries , scar , or postoperative.

Some of the theoretical advantages of topography-driven photorefractive keratectomy (PRK) are a better astigmatic correction, the possibility of correcting irregular astigmatism, and a smaller ablation volume compared with standard treatments, resulting in better visual performance.

Aim of the work To evaluate the efficacy, safety, and predictability of topography-guided photorefractive keratectomy (PRK) to improve refractive status of patient with irregular Cornea.

Condition or disease Intervention/treatment Phase
Irregular Astigmatism Procedure: photorefractive keratectomy (PRK) Not Applicable

Layout table for study information
Study Type : Interventional  (Clinical Trial)
Actual Enrollment : 20 participants
Allocation: N/A
Intervention Model: Single Group Assignment
Masking: None (Open Label)
Primary Purpose: Treatment
Official Title: Visual Outcomes of Topography Guided Photorefractive Keratectomy (PRK) for Treatment of Patients With Irregular Cornea
Actual Study Start Date : March 1, 2017
Actual Primary Completion Date : March 1, 2018
Actual Study Completion Date : March 1, 2018

Resource links provided by the National Library of Medicine

Arm Intervention/treatment
Experimental: Corneal Topography
we will do Corneal Topography for every patient before doing photorefractive keratectomy (PRK) and also after it , to measure the change in the quality of vision and measure the change in the quality of vision
Procedure: photorefractive keratectomy (PRK)
The cornea will be ablated while the patient fixating on target light under constant eye-tracking control. The ablations will be made using the "ALLEGRETTO X 500WAVE excimer laser" (WaveLight Laser Technologie AG).
Other Name: PRK

Primary Outcome Measures :
  1. Visual Acuity [ Time Frame: follow up after 1 day, 1 week, 1 month and 3 months ]
    The measure of the Visual Acuity and Best Corrected Visual acuity Using the Snellen Chart which give use an idea about visual acuity in Metric scale (e.g. 6\6 , 6\12)

Secondary Outcome Measures :
  1. Refractive State [ Time Frame: follow up after 1 day, 1 week, 1 month and 3 months ]
    We will measure the Refractive state of the eye by using the Auto refractor which give us an idea about the refractive state in a Diopteric scale ( e.g. -2D , +4 D) .

Information from the National Library of Medicine

Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the contacts provided below. For general information, Learn About Clinical Studies.

Layout table for eligibility information
Ages Eligible for Study:   Child, Adult, Older Adult
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No

Inclusion Criteria:

  • Patients with irregular corneal astigmatism caused by:

    • Trauma.
    • Non - Central Corneal Scars.
    • Previous corneal surgery.
  • With No other abnormalities in the eye.
  • Patient is willing to enter the study and sign a consent.

Exclusion Criteria:

  • Patients with central corneal scars.
  • Patients with central haze interfering with visual acuity.
  • Patients with ectasia at corneal graft margins.
  • Patients with irregular astigmatism caused by corneal ectasia or keratoconus.
  • Patients had refractive surgery with ablations leaving a residual corneal thickness less than 250 μm.

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its identifier (NCT number): NCT03140046

Layout table for location information
Assiut University
Assiut, Egypt
Sponsors and Collaborators
Assiut University
Layout table for additonal information
Responsible Party: Ahmed Abdelsamee Mohammed, Dr, Assiut University Identifier: NCT03140046    
Other Study ID Numbers: PRK
First Posted: May 4, 2017    Key Record Dates
Last Update Posted: May 11, 2020
Last Verified: May 2020
Individual Participant Data (IPD) Sharing Statement:
Plan to Share IPD: No

Layout table for additional information
Studies a U.S. FDA-regulated Drug Product: No
Studies a U.S. FDA-regulated Device Product: No
Additional relevant MeSH terms:
Layout table for MeSH terms
Refractive Errors
Eye Diseases