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Completed

NCT Number: NCT04426175

Z8 OCT-controlled 2D vs 3D LASIK

The aim of this study was to test the hypothesis that OCT-guided 110 µm targeted flaps will result in accurate, predictable, and precise thickness flaps, with low complication rates when performed and compared using both 2D and 3D flap geometry applications and how it correlated to visual experience and quality of life responses during the early postoperative period.

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Key information

Conditions

Myopia Astigmatism Eye Diseases Refractive Errors

Age range

18 year and older

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Zentrumsehstärke

Hamburg, 20251, Germany

About this study

It has been postulated that it is possible with the Ziemer Femtosecond LDV laser system to create reproducible flaps in terms of thickness and predictability. The aim of this study was to test the hypothesis that OCT-guided 110 µm targeted flaps will result in accurate, predictable, and precise thickness flaps, with low complication rates when performed and compared using both 2D and 3D flap geometry applications. Patient-reported outcomes are increasingly incorporated into clinical trials as they provide access to valuable information on the physical experience of the patient during and after the treatment. A questionnaire will therefore also be introduced in this study to evaluate how well self-reported pain, visual experience, and quality of life responses are correlated with flap geometries in both groups during the early postoperative period. The study holds direct medical benefit to the patient in this that they received an immediate improvement in his/her unaided vision. Moreover, the patient's participation contributes to the medical knowledge about the use of femtosecond lasers for refractive surgery, in particular in view of the use of intraoperative OCT visualization tools. The patients will gain access to the newest technology available for refractive surgery namely a low pulse energy high-frequency femtosecond laser.

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

Key inclusion criteria as described by the German Commission for Refractive Surgery (KRC) are:

  • The recommended range of application for the correction of myopia is up to -8.00 D and for the correction of astigmatism up to 5.00 D.
  • The limited for LASIK correction of myopia is up to -10.00 D and correction of astigmatism up to 6.00 D. If myopic astigmatism is to be corrected, the values for myopia and astigmatism must be added together.
  • The recommended range for correction of hyperopia is up to 3.00 D. Up to 4.00 D is the range of limited application for hyperopia.
  • Age ≥18 years with stable eyesight for over 12 months.

Exclusion criteria

Key exclusion criteria as described by the German Commission for Refractive Surgery (KRC):

  • preoperative corneal thickness less than 480 μm
  • predicted stromal thickness under the flap after ablation of less than 250 μm
  • chronic progressive corneal disease and forme fruste keratoconus
  • surgery before the age of 18 years
  • symptomatic cataract
  • Glaucoma with a marked loss of visual field
  • Exudative macular degeneration.
  • Concurrent participation in another ophthalmological clinical study

Exclusion criteria

irrespective of the KRC criteria:

  • Undergone former eye surgery
  • Contact lens wear within the two weeks prior to commencement of preoperative measurements

Treatment and study plan

2D and 3D cutting method using a low energy Femtosecond laser LDV Z8 for LASIK flap cutting

Device

2D and 3D cutting methods were randomly used in same subjects

Primary outcomes

  1. Predictability of central flap thickness in OCT-controlled 110 µm LASIK

    Time frame: 1 month postoperatively

    Analyze central flap thickness in OCT-controlled 110 µm LASIK and to report on intended versus achieved flap thickness of one group with a 2D flap geometry in one eye and another group with a 3D flap geometry in the contralateral eye. All OCT measurements will be done in micron metres (µm).

Secondary outcomes

  1. Comparison of intraoperative flap thickness with pre- and postoperative results

    Time frame: 1 week, 1 month

    Measurement of corneal thickness pre flap creation (Corneal Pachymetry measurements expressed in µm indicate the thickness of the cornea before flap was created. This measurement will serve as the baseline measurement. Pachymetry measured again after the flap was created and lifted by means of optical and ultrasonic pachymetry(µm) for both groups and to be compare with postoperative AS-OCT measurements also measured in µm.This will indicate how accurate the intraoperative flap thickness compare to the 1 week and 1 month thickness measurements as swelling and inflammatory processes could influence postoperative measurements.

  2. Postoperative planarity

    Time frame: 1 week, 1 month

    Assessment of several measurements taken along the corneal cut on superior, nasal, inferior and temporal points in order to compare the uniformity of the cut between 2D vs 3D geometries. Measurments will be done by means of AS-OCT,measured in µm units.Measurements at two different follow up periods will be analyzed and compared in order to rule out the role that inflammation could possibly play.

  3. Intraoperative flap morphology

    Time frame: During surgery

    Observations that are defined by different scales in order to report on important features pertaining to 2D and 3D intraoperative flap geometries eg. the presence and extent of opaque bubble layer (OBL), ease of flap lifting and stromal bed quality in both groups . Intraoperative flap morphology assessment to be done as soon as the flap was created in terms of presence of an opaque bubble layer (no OBL, 30-40% of flap surface, >40% of flap surface). Once the flap was lifted to report on ease of flap lifting (easy/sticky/can not lift) and to describe the stromal bed quality (smooth,tissue bridges, rastered, lines).

  4. Postoperative flap properties

    Time frame: 1 week, 1 month

    Evaluate flap properties by means of slit lamp biomicroscopy examination. The flap's visual appearance seen with the slit lamp to be described and documented as per the suggested scales during 2 specified follow up visits in terms of edge quality and visibility ('yes/no' If yes= extreme fine line, distinct line or irregular edge), border shape (round, irregular) and interface quality (smooth, lines, cobblestones, grids, microstriae) and be compared between flap geometries (2D and 3D flaps).

  5. Visual outcomes

    Time frame: 1 day, 1 week, 1 month

    Compare pre- and postoperative visual acuity (UDVA, CDVA) measurements by means of a Snellen Visual Acuity chart and be expressed in decimal that will be converted to logMar units for the purpose of statistical analysis.

  6. Patient reported Outcomes: early recovery period

    Time frame: 1 day, 2Day, 1 week follow up

    Conduct a non validated Patient Reported Outcome (PRO) questionnaire adopted and based on the 'Brief Pain Inventory' questionnaire [Porela-Tiihonen] to assess patient's early visual perceptions and pain experience related to their own functional status and wellbeing and to compare between the two eyes since each undergone different cutting geometry (2D vs 3D) methods.

  7. Complications

    Time frame: Intra- and postoperatively up to 1 month follow up

    Report and document any intra- and postoperative complications that may occur during the time of the procedure or at the 1 month follow up visit.

Sponsors and collaborators

Lead sponsor

Zentrumsehstarke Hamburg

Industry

Registry information

Official study title

Precision of 2D vs 3D Low Energy Femto-LASIK: Intraoperative and Postoperative OCT-based Study

Important dates

Study start
2019
Primary completion
2020
Study completion
2020
First posted
Jun 11, 2020
Registry last updated
Jun 11, 2020

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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