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

Federal University of São Paulo

Status: Completed

Conditions: Surgical Procedure, Unspecified

Treatments: Procedure: PRK group; Procedure: CXL + PRK group

Study type: Interventional

Funder types: Other

Identifiers

NCT02943967

2088/88

Details and patient eligibility

About

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.

Full 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.

Enrollment: 44 patients

Sex: All

Ages: 23 to 51 years old

Volunteers: Accepts Healthy Volunteers

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

Trial design

Primary purpose: Treatment

Allocation: Randomized

Interventional model: Parallel Assignment

Masking: None (Open label)

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44 participants in 2 patient groups

CXL + PRK group

Active Comparator group

Description:

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

Treatment:

Procedure: CXL + PRK group

PRK group

Active Comparator group

Description:

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

Treatment:

Procedure: PRK group