Corneal Cross-linking and Refractive Surface Ablation in Patients With Asymmetric Corneas

Not Applicable

Completed

• Conditions: Surgical Procedure, Unspecified

• Registration Number: NCT02943967
• Lead Sponsor: Federal University of São Paulo

Brief Summary

The purpose of this study is to evaluate safety and efficacy of corneal cross-linking and photorefractive keratectomy for refractive correction in patients with bilateral asymmetric topography.

Detailed Description

Corneal cross-linking (CXL) by the photosensitizer, riboflavin (vitamin B2), and ultraviolet A (UVA) light increases corneal rigidity and has been described as an effective method for stabilizing the cornea in patients with progressive keratoconus. The photochemical reaction in this procedure causes the collagen to form additional covalent connections between its fibers, which stabilizes the stromal collagen fibers, improving the collagen's structure and the cornea rigidity. It is a relatively safe procedure with low rates of complications Photorefractive keratectomy (PRK) it is a traditional technique for refractive surgery. In cases of irregular corneas or re-operation normally the favorite ablation profile chosen is the guided surgery, topography guided or wavefront guided, showing better results. This technique is also relatively safe procedure with low rates of complications. One of the most unwanted complications of this surgery and also rare is corneal ectasia.

Combining PRK and CXL is already done in patients with keratoconus and suspected keratoconus.

This combined procedure uses the principle that CXL stiffen the cornea making it possible to reduce corneal thickness with PRK without weakening corneal strength. Literature show better results, in keratoconus, with simultaneous procedures. Guedj et al performed PRK in keratoconus suspects and within 5 years he did not found any corneal ectasia.

Study Timeline

• Study Start: 2010-01
• Primary Completion: 2014-01
• Study Completion: 2014-01
• Status Verified: 2016-10
• Study First Submitted: 2016-10-21
• Study First Submitted QC: 2016-10-21
• Last Update Submitted: 2016-10-24
• Study First Posted: 2016-10-25
• Last Update Posted: 2016-10-26

Recruitment & Eligibility

• Status: COMPLETED
• Sex: All
• Target Recruitment: 44

Inclusion Criteria

• bilateral asymmetric topography with inferior steepening
• corneal thickness of 440 micra at the thinnest point
• inferior-to-superior index (I-S) between 1.0D and 1.4D
• maximum keratometric steepness < 47.00D
• stable refraction more than 1 year.

Exclusion Criteria

• forme fruste keratoconus and keratoconus
• previous eye surgery
• previous eye trauma
• confirmed pregnancy

Study & Design

• Study Type: INTERVENTIONAL
• Study Design: PARALLEL

Primary Outcome Measures

Name	Time	Method
Refractive results - spherical equivalent in diopters	30 months

Secondary Outcome Measures

Name	Time	Method
Biomicroscopy findings with the slit lamp	30 months
Aberrometric Results in root mean square	18 months	Only coma and spherical aberration
Topographic results in diopters	30 months	we will measure the increase in diopters with time
Pachymetric results in micra	30 months
Visual acuity in logMar	30 months

Trial Locations

Locations (1)

Federal University of São Paulo; 🇧🇷 Sao Paulo, Brazil