Comparison of Cross-cylinder and Conventional Photorefractive Keratectomy(PRK) in Correcting Medium-high Astigmatism

NCT ID: NCT00663923

Last Updated: 2012-03-13

Basic Information

• Recruitment Status: COMPLETED
• Clinical Phase: PHASE3
• Total Enrollment: 50 participants
• Study Classification: INTERVENTIONAL
• Study Start Date: 2007-11-30
• Study Completion Date: 2009-12-31

Brief Summary

The purpose of this study is to determine whether cross-cylinder approach is more effective than routine method in laser correction of astigmatism.

Detailed Description

Both eyes of 50 patients(100 eyes) with medium-high compound myopic astigmatism and inclusion criteria,will be treated by photorefractive keratectomy (PRK) using excimer laser.It breaks chemical bonds within corneal stroma.It's wavelength is 193 nm that is in the ultraviolets range with high energy and very low tissue penetrance. The right or left eye of every patient would be allocated randomly to one of the study groups using RandList 1.1. In spite of recent advances in excimer laser machines and surgical techniques,correction of astigmatism is not more successful compared to myopia. In this study we will compare two methods of laser correction of astigmatism regarding to visual acuity,residual error and aberrations.

Conditions

Astigmatism

Study Design

• Allocation Method: RANDOMIZED
• Intervention Model: PARALLEL
• Primary Study Purpose: TREATMENT
• Blinding Strategy: SINGLE

Study Groups

cross-cylinder

In this technique the laser is programmed with the axis and amount of cylinder,so that the steepest meridian is flattened with central cylindrical ablation and the flattest meridian steepens with paracentral ablation

Group Type: EXPERIMENTAL

photorefractive keratectomy (PRK)

Intervention Type: PROCEDURE

comparison of PRK by cross-cylinder approach in one eye and conventional (single) method in the other eye for laser correction of astigmatism

single

In this technique ,cylinder is treated only on one meridian by performing an elliptical ablation to to flatten the steeper meridian to match the flatter meridian.

Group Type: ACTIVE_COMPARATOR

photorefractive keratectomy (PRK)

Intervention Type: PROCEDURE

comparison of PRK by cross-cylinder approach in one eye and conventional (single) method in the other eye for laser correction of astigmatism

Interventions

photorefractive keratectomy (PRK)

comparison of PRK by cross-cylinder approach in one eye and conventional (single) method in the other eye for laser correction of astigmatism

Intervention Type: PROCEDURE

Other Intervention Names

photoastigmatic keratectomy

Eligibility Criteria

Inclusion Criteria

• >20 years of age
• refractive stability for at least one year
• regular and symmetric astigmatism of >1.5 diopters

Exclusion Criteria

• corneal thickness<470 microns
• keratoconus or suspected keratoconus
• active ocular disease and systemic collagen disease

• Minimum Eligible Age: 20 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: Yes

Sponsors

Tabriz University

OTHER

Sponsor Role: lead

Responsible Party

Responsibility Role: SPONSOR

Principal Investigators

Mohammad R Sedghipoor, MD

Role: STUDY_DIRECTOR

Ophthalmology Department, Tabriz University of medical Sciences

Locations

Nikookari eye hospital

Tabriz, East Azerbaijan Province, Iran

Countries

Iran

Other Identifiers

86-43

Identifier Type: -

Identifier Source: org_study_id