Surgical Procedure, Unspecified
Conditions
Keywords
Refractive Surgical Procedures, Photorefractive Keratectomy, Aberrometry
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.
Interventions
PROCEDURECXL + PRK group
Corneal cross-linking with subsequent photorefractive keratotomy after 6 months was performed in one eye
PROCEDUREPRK group
Photorefractive keratotomy alone was performed in contra lateral eyes
Sponsors
Federal University of São Paulo
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
NONE
Eligibility
Sex/Gender
ALL
Age
23 Years to 51 Years
Healthy volunteers
Yes
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
Design outcomes
Primary
| Measure | Time frame |
|---|---|
| Refractive results - spherical equivalent in diopters | 30 months |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Biomicroscopy findings with the slit lamp | 30 months | — |
| Visual acuity in logMar | 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 | — |
Countries
Brazil
Outcome results
None listed