T-Cat Laser & Cross-linking for Keratoconus (T-Cat)

Pilot Study of Excimer Laser Topography-Computer Assisted Treatment (T-Cat) Combined With Corneal Collagen Cross-linking With Riboflavin and UV Light

The purpose of this study is to determine whether excimer laser corneal surface ablation (T-Cat) can be safely combined with simultaneous corneal collagen cross-linking treatment to produce an improved and stable corneal profile in the treatment of keratoconus.

Study Overview

Detailed Description

Theoretical framework:

Corneal ectasia is a relative weakness in the structure of the cornea, which produces a progressive change in its shape with resultant visual distortion.

Excimer laser surface ablation can be used to re-shape the corneal profile. When the corneal shape is very irregular, corneal topography data gives the best information as to how to re-shape the cornea into a normal profile, and this Topography-Computer Assisted Treatment (T-Cat) will be used to modulate the surface corneal shape.

It is known that collagen cross-linking in the cornea occurs naturally with age, and in diabetes, both of which seem to prevent progressive ectasia. Corneal collagen cross-linking with riboflavin has been shown to stabilize the cornea in keratoconus, and prevents progression of the disease. If cross-linking is performed at that moment that the cornea has been re-shaped by T-Cat treatment, it should help prevent the corneal thinning resultant from the laser treatment from destabilising the cornea and causing progressive ectasia.

Purpose:

To determine whether excimer laser corneal surface ablation (T-Cat) can be safely combined with simultaneous corneal collagen cross-linking treatment to produce an improved and stable corneal profile.

Design:

Prospective, interventional trial.

Study Type

Interventional

Enrollment (Actual)

15

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

      • London, United Kingdom, SW17 0QT
        • Moorfields Eye Department at St George's Hospital

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

18 years to 50 years (Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

All

Description

Inclusion Criteria:

  • Patients with known keratoconus or pellucid marginal degeneration.

Exclusion Criteria:

  • Age < 18 years > 50 years.
  • Minimal corneal pachymetry in eye to be treated of < 400μ.
  • Evidence of other corneal disease in the eye to be treated (e.g. Herpes simplex keratitis).
  • Women who are pregnant or nursing at the time of the initial treatment.
  • Presence of significant central corneal opacity.
  • Patients unwilling to not wear rigid contact lenses in the eye to be operated on for at least one month before baseline examination, and for the first six months post-operatively.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Non-Randomized
  • Interventional Model: Single Group Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Interventional study
Patients with known keratoconus or pellucid marginal degeneration will be invited to join the study. The study is partly a continuation in the management of patients who have had previous keratophakia, who will have near-normal or supra-physiological levels of corneal thickness. It is also intended for patients with relatively mild keratoconus who have sufficient corneal thickness to allow a limited laser ablation whilst still leaving a residual stromal bed of at least 350μ.
Surgery is performed with topical anaesthesia. The central corneal epithelium is removed. Excimer laser ablation is applied (typically 15-30 seconds). Residual bed thickness is checked with an ultrasonic pachymeter. Topical application of riboflavin 0.1% in dextran is commenced at 5 minute intervals. When an adequate saturation of the anterior chamber with riboflavin has been achieved, cross-linking treatment will proceed. Output from the UV light generating equipment is measured with a UV light meter and set at 3mW/cm². Thirty minutes of treatment is given, interrupted at five minute intervals by the application of more topical riboflavin drops. Finally the eye has a bandage soft contact lens placed, with preservative free topical antibiotic, steroid, and cycloplegic drop application.
Other Names:
  • Ricrolin (riboflavin 0.1% in dextran)
  • Pecshke UV-X illumination system

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Time Frame
The difference in the pre- and post-operative unaided visual acuity, best corrected visual acuity, and refraction.
Time Frame: At six months
At six months

Secondary Outcome Measures

Outcome Measure
Time Frame
Corneal topographic profile.
Time Frame: At six months
At six months

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Investigators

  • Principal Investigator: Chad K Rostron, MB BS, Moorfields Eye Hospital NHS Foundation Trust

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start

October 1, 2008

Primary Completion (Actual)

October 1, 2010

Study Completion (Actual)

October 1, 2010

Study Registration Dates

First Submitted

October 21, 2008

First Submitted That Met QC Criteria

October 21, 2008

First Posted (Estimate)

October 22, 2008

Study Record Updates

Last Update Posted (Estimate)

July 21, 2011

Last Update Submitted That Met QC Criteria

July 20, 2011

Last Verified

April 1, 2009

More Information

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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