T-Cat Laser & Cross-linking for Keratoconus

NCT ID: NCT00777322

Last Updated: 2011-07-21

Basic Information

• Recruitment Status: COMPLETED
• Clinical Phase: NA
• Total Enrollment: 15 participants
• Study Classification: INTERVENTIONAL
• Study Start Date: 2008-10-31
• Study Completion Date: 2010-10-31

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.

Conditions

Keratoconus; Pellucid Marginal Degeneration

Study Design

• Allocation Method: NON_RANDOMIZED
• Intervention Model: SINGLE_GROUP
• Primary Study Purpose: TREATMENT
• Blinding Strategy: NONE

Study Groups

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.

Group Type: EXPERIMENTAL

Excimer laser ablation, and collagen cross-linking

Intervention Type: PROCEDURE

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.

Interventions

Excimer laser ablation, and collagen cross-linking

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.

Intervention Type: PROCEDURE

Other Intervention Names

Ricrolin (riboflavin 0.1% in dextran); Pecshke UV-X illumination system

Eligibility Criteria

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.

• Minimum Eligible Age: 18 Years
• Maximum Eligible Age: 50 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: No

Sponsors

Accuvision Laser Eye Clinics

OTHER

Sponsor Role: collaborator

Carleton Optical Equipment Ltd.

INDUSTRY

Sponsor Role: collaborator

Bon Optics

OTHER

Sponsor Role: collaborator

Sooft Italia

INDUSTRY

Sponsor Role: collaborator

Moorfields Eye Hospital NHS Foundation Trust

OTHER

Sponsor Role: lead

Responsible Party

Moorfields Eye Hospital

Principal Investigators

Chad K Rostron, MB BS

Role: PRINCIPAL_INVESTIGATOR

Moorfields Eye Hospital NHS Foundation Trust

Locations

Moorfields Eye Department at St George's Hospital

London, London, United Kingdom

Countries

United Kingdom

Other Identifiers

REC Ref: 07/H0721/94

Identifier Type: -

Identifier Source: org_study_id