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

Democritus University of Thrace

Status: Completed

Conditions: Astigmatism

Treatments: Other: Photorefractive keratectomy (PRK); Other: Laser in situ keratomileusis (LASIK)

Study type: Interventional

Funder types: Other

Identifiers

NCT01432834

23/29-07-11

Details and patient eligibility

About

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).

Full 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).

Enrollment: 74 patients

Sex: All

Ages: 18+ years old

Volunteers: No Healthy Volunteers

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

Trial design

Primary purpose: Treatment

Allocation: Non-Randomized

Interventional model: Parallel Assignment

Masking: None (Open label)

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74 participants in 2 patient groups

LASIK group (LG group)

Other group

Description:

Volunteers of this group received LASIK treatment.

Treatment:

Other: Laser in situ keratomileusis (LASIK)

PRK group (PG group)

Other group

Description:

Volunteers of this group received PRK treatment

Treatment:

Other: Photorefractive keratectomy (PRK)