T-Cat Laser & Cross-linking for Keratoconus

Not Applicable

Completed

• Conditions: Keratoconus; Pellucid Marginal Degeneration
• Interventions: Procedure: Excimer laser ablation, and collagen cross-linking

• Registration Number: NCT00777322
• Lead Sponsor: Moorfields Eye Hospital NHS Foundation Trust

Brief Summary

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.

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 Timeline

• Study Start: 2008-10
• Study First Submitted: 2008-10-21
• Study First Submitted QC: 2008-10-21
• Study First Posted: 2008-10-22
• Status Verified: 2009-04
• Primary Completion: 2010-10
• Study Completion: 2010-10
• Last Update Submitted: 2011-07-20
• Last Update Posted: 2011-07-21

Recruitment & Eligibility

• Status: COMPLETED
• Sex: All
• Target Recruitment: 15

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 & Design

• Study Type: INTERVENTIONAL
• Study Design: SINGLE_GROUP

Arm && Interventions

Group	Intervention	Description
Interventional study	Excimer laser ablation, and collagen cross-linking	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.

Primary Outcome Measures

Name	Time	Method
The difference in the pre- and post-operative unaided visual acuity, best corrected visual acuity, and refraction.	At six months

Secondary Outcome Measures

Name	Time	Method
Corneal topographic profile.	At six months

Trial Locations

Locations (1)

Moorfields Eye Department at St George's Hospital; 🇬🇧 London, United Kingdom