Efficacy of the Wavefront Optimized (WFO) Profile in Non-anterior Astigmatisms

Not Applicable

Completed

• Conditions: Astigmatism
• Interventions: Other: Laser in situ keratomileusis (LASIK); Other: Photorefractive keratectomy (PRK)

• Registration Number: NCT01432834
• Lead Sponsor: Democritus University of Thrace

Brief Summary

The purpose of the study was to assess the efficacy of the Allegretto Wave excimer laser and the wavefront optimized ablation profile in correcting primarily non-anterior astigmatism faults, following laser in-situ keratomileusis (LASIK) and photorefractive keratectomy (PRK).

Detailed Description

Different optical components of the eye contribute to the total astigmatism error.In specific, the anterior corneal surface is responsible for the anterior component of astigmatism fault (anterior astigmatism), while the posterior corneal surface and the lens are responsible for the posterior one (posterior astigmatism).

Regarding our study, 74 refractive surgery candidates were recruited. Only one eye from each candidate was randomly enrolled in the study. Of them, 40 eyes underwent LASIK treatment (LG group), while 34 eyes underwent PRK treatment (PG group). The Allegretto Wave excimer laser (software version: 2.020 / WaveLight AG, Erlangen, Germany) was used for the ablation in all groups. Preoperatively, the ocular residual astigmatism (ORA) was calculated for each eye, according to which each astigmatism fault was characterized as primarily anterior or non-anterior.ORA is the vectorial value of astigmatism arising from non-anterior sources. Its amount on total astigmatism (R) is determined by the magnitude ratio ORA/R. Ratios below 1 indicate primarily anterior astigmatism, while ratios above 1 indicate primarily non-anterior astigmatism. 20 LG eyes and 16 PG eyes presented primarily anterior astigmatism (LG-A and PG-A subgroups, respectively), while 20 LG eyes and 18 PG eyes demonstrated primarily non-anterior astigmatism (LG-NA and PG-NA subgroups, respectively). Postoperatively, vector analysis of astigmatism correction was conducted; The following indexes were calculated: a) Correction index (CI), b) Difference vector (DV) and c) Index of Success (IOS).

Study Timeline

• Study Start: 2010-04
• Primary Completion: 2010-12
• Study Completion: 2011-04
• Study First Submitted: 2011-09-12
• Study First Submitted QC: 2011-09-12
• Study First Posted: 2011-09-13
• Status Verified: 2017-01
• Last Update Submitted: 2017-01-14
• Last Update Posted: 2017-01-18

Recruitment & Eligibility

• Status: COMPLETED
• Sex: All
• Target Recruitment: 74

Inclusion Criteria

• astigmatism fault

Exclusion Criteria

• previous incisional eye surgery
• evidence of any type of corneal pathology
• evidence of any type of optic neuropathy
• history of optic neuropathy
• diabetes mellitus

Study & Design

• Study Type: INTERVENTIONAL
• Study Design: PARALLEL

Arm && Interventions

Group	Intervention	Description
LASIK group (LG group)	Laser in situ keratomileusis (LASIK)	Volunteers of this group received LASIK treatment.
PRK group (PG group)	Photorefractive keratectomy (PRK)	Volunteers of this group received PRK treatment

Primary Outcome Measures

Name	Time	Method
vector analysis of astigmatism correction, following laser in-situ keratomileusis (LASIK) & photorefractive keratectomy (PRK) treatments.	6 months postoperatively	Vector analysis of astigmatism correction was conducted using preoperative and 6-month postoperative data. The following indexes were calculated: a) Correction index (CI) which is determined by the ratio of the surgically induced astigmatism (SIA) to the target induced astigmatism (TIA), b) Difference vector (DV) as an absolute measure of success, and, c) Index of Success (IOS) which is determined by the relationship of the DV to the TIA, as a relative measure of success.

Trial Locations

Locations (1)

Eye Institute of Thrace (EIT); 🇬🇷 Alexandroupolis, Greece