Corneal Cross-linking and Refractive Surface Ablation in Patients With Asymmetric Corneas
- Conditions
- Surgical Procedure, Unspecified
- Interventions
- Procedure: PRK groupProcedure: CXL + PRK group
- 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.
Recruitment & Eligibility
- Status
- COMPLETED
- Sex
- All
- Target Recruitment
- 44
- 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.
- forme fruste keratoconus and keratoconus
- previous eye surgery
- previous eye trauma
- confirmed pregnancy
Study & Design
- Study Type
- INTERVENTIONAL
- Study Design
- PARALLEL
- Arm && Interventions
Group Intervention Description PRK group PRK group Photorefractive keratotomy will be perfomed in the fellow eye using excimer laser Ladarvision (Alcon - USA) with 0,02 % mitomicin for 30 seconds (Ophthalmos - Brasil) simultaneously with the other eye. Both procedures will have the same post operative treatment : gatifloxacin 0,3% 6/6h for 10 days prednisolone acetate 0,12% 6/6h por 14 days CXL + PRK group CXL + PRK group Corneal cross-linking surgery is perfomed in one eye : deepithelization of the cornea and instillation of 0,1% riboflavin (ophthalmos - Brazil) for 30 minutes and UVA for irradiated for 30 minutes with ultraviolet-A of 365nm light with an irradiance of 3 mW/cm2 using Xlink (Opto - São Carlos) Photorefractive keratotomy will be perfomed in the same eye using excimer laser Ladarvision (Alcon - USA) with 0,02 % mitomicin for 30 seconds (Ophthalmos - Brasil) simultaneously with the other eye. Both procedures will have the same post operative treatment : gatifloxacin 0,3% 6/6h for 10 days prednisolone acetate 0,12% 6/6h por 14 days
- Primary Outcome Measures
Name Time Method Refractive results - spherical equivalent in diopters 30 months
- Secondary Outcome Measures
Name Time Method Visual acuity in logMar 30 months 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
Trial Locations
- Locations (1)
Federal University of São Paulo
🇧🇷Sao Paulo, Brazil