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

This study has been completed.
Sponsor:
Information provided by (Responsible Party):
Georgios Labiris, Democritus University of Thrace
ClinicalTrials.gov Identifier:
NCT01432834
First received: September 12, 2011
Last updated: NA
Last verified: September 2011
History: No changes posted
  Purpose

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).


Condition Intervention
Astigmatism
 Other: Laser in situ keratomileusis (LASIK)
Other: Photorefractive keratectomy (PRK)

Study Type: Interventional
Study Design: Allocation: Non-Randomized
Endpoint Classification: Efficacy Study
Intervention Model: Parallel Assignment
Masking: Open Label
Primary Purpose: Treatment
Official Title: Evaluation of the Efficacy of the Allegretto Wave and the Wavefront Optimized Ablation Profile in Non-anterior Astigmatisms

Further study details as provided by Democritus University of Thrace:

Primary Outcome Measures:
  • vector analysis of astigmatism correction, following laser in-situ keratomileusis (LASIK) & photorefractive keratectomy (PRK) treatments. [ Time Frame: 6 months postoperatively ] [ Designated as safety issue: No ]
    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.


Enrollment: 74
Study Start Date: April 2010
Study Completion Date: April 2011
Primary Completion Date: December 2010 (Final data collection date for primary outcome measure)
Arms Assigned Interventions
LASIK group (LG group)
Volunteers of this group received LASIK treatment.
 Other: Laser in situ keratomileusis (LASIK)
During LASIK treatments the Carriazo-Pendular microkeratome (SCHWIND eye-tech-solutions GmbH & Co.KG, Kleinostheim, Germany) with 130μm cutting head was used for the creation of the flap. The normal value of the negative pressure of the suction ring was between 600-620 mmHg and the velocity of the head movement was constant (3mm/sec). The hinge was created at the 12 o'clock position. The Allegretto Wave excimer laser (software version: 2.020 / WaveLight AG, Erlangen, Germany) was used for all ablations. Attempted ablations were modified according to the "S001 Wellington" nomogram for the "wavefront optimised" protocol.
Other Names:
  • Allegretto Wave excimer laser (software version: 2.020 / WaveLight AG, Erlangen, Germany)
  • Carriazo-Pendular microkeratome (SCHWIND eye-tech-solutions GmbH & Co.KG, Kleinostheim, Germany)
PRK group (PG group)
Volunteers of this group received PRK treatment
 Other: Photorefractive keratectomy (PRK)
The same surgical procedure was applied to all PG participants that included: Instillation of proparacaine hydrochloride 0.5% drops for topical anaesthesia, application of a sponge saturated with 10% alcohol to the central cornea for 20-30 seconds and subsequent de-epithelialization by means of a hockey knife.The Allegretto Wave excimer laser (software version: 2.020 / WaveLight AG, Erlangen, Germany) was used for all ablations. Attempted ablations were modified according to the "S001 Wellington" nomogram for the "wavefront optimised" protocol. A soft therapeutic lens was applied until complete re-epithelialization of the cornea was detected.
Other Name: Allegretto Wave excimer laser (software version: 2.020 / WaveLight AG, Erlangen, Germany)

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).

  Eligibility

Ages Eligible for Study:   18 Years and older
Genders Eligible for Study:   Both
Accepts Healthy Volunteers:   No
Criteria

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
  Contacts and Locations
Please refer to this study by its ClinicalTrials.gov identifier: NCT01432834

Locations
Greece
Eye Institute of Thrace (EIT)
Alexandroupolis, Greece, 68100
Sponsors and Collaborators
Democritus University of Thrace
  More Information

No publications provided

Responsible Party: Georgios Labiris, Senior Lecturer of Ophthalmology, Democritus University of Thrace
ClinicalTrials.gov Identifier: NCT01432834     History of Changes
Other Study ID Numbers: 23/29-07-11
Study First Received: September 12, 2011
Last Updated: September 12, 2011
Health Authority: Greece: Ethics Committee

Keywords provided by Democritus University of Thrace:
non-anterior astigmatism correction
Allegretto Wave excimer laser
wavefront optimized ablation profile (WFO)
LASIK
PRK

Additional relevant MeSH terms:
Astigmatism
Refractive Errors
Eye Diseases

ClinicalTrials.gov processed this record on May 21, 2013