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NCT Number: NCT02550353

Changes Between Lenticule Extraction and Femtosecond Laser-assisted Laser in Situ Keratomileusis

The aim is to evaluate the short-term changes in ocular surface measures and tear inflammatory mediators after lenticule extraction (FLEx) and femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK) procedures.

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Key information

Conditions

Myopia Astigmatism Eye Diseases Lacerations Refractive Errors Wounds and Injuries

Age range

18 year–30 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Hainan Eye Hospital, Zhongshan Ophthalmic Center of Sun Yat-sen University

Haikou, Hainan, 570311, China

About this study

Over the past few years, laser in situ keratomileusis with a femtosecond laser-created flap (FS-LASIK)has been a popular ophthalmic procedure for the correction of refractive error. This first all-in-one FS-laser system was designed to perform the refractive lenticule extraction (ReLEx) procedures, femtosecond lenticule extraction (FLEx).They have the same feature: corneal flap.

Ocular surface disruption during corneal refractive surgery is commonly considered to be closely related to the development of dry eye. Multiple etiologies contribute to this ocular surface disruption, including the flap creation and stromal ablation involved in previous refractive surgery techniques. Corneal nerve damage has been considered the main cause of dry eye, due to disrupted afferent sensory nerves, reduced blink reflex, and increased tear evaporation leading to tear film instability. In addition, postoperative inflammatory mediator fluctuations are also a key factor related to ocular surface damage. Extensive research has described the effects of cytokines, chemokines and growth factors in modulating corneal wound healing, cell migration, and apoptosis on the ocular surface after refractive surgery.

This prospective clinical study is going to assess the short-term changes in ocular surface measures and tear inflammatory mediators after lenticule extraction (FLEx) and femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK) procedures.

Who can participate

Healthy volunteers accepted: Yes

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

Inclusion criteria

  • minimum age of 18 years(range from 18 year to 25 years)
  • corneal thickness 500 μm with calculated residual stromal bed after treatment greater than 300 μm
  • preoperative spherical equivalent refraction between- 2.00 diopter (D) and -6.50 D.preoperative cylindrical equivalent refraction between -0.25 D and -1.50 D.
  • preoperative corneal curvature from 41.0 D to 46.0 D with a regular topographic pattern monocular best corrected visual acuity of 20/20 or better and stable refractive error (less than 0.5 D change) for 24 months before surgery。

Exclusion criteria

  • systemic disease that contraindicated the surgery (such as diabetes, glaucoma and systemic collagen vascular disease)
  • corneal abnormality or disease.
  • a history of tear supplement usage or contact lens wear during the past year.

Treatment and study plan

lenticule extraction

Procedure

Four femtosecond incisions were created in succession: the posterior surface of the refractive lenticule (spiral in), the lenticule border, the anterior surface of the refractive lenticule (spiral out), and the corneal flap in the superior region. After the suction was released, the flap was opened using a thin, blunt spatula and the free refractive lenticule was subsequently grasped with a forceps and extracted, after which the flap was repositioned carefully.

femtosecond laser-assisted laser in situ keratomileusis

Procedure

track distance and spot distance were 3.0 μm during flap creation and 1.5 μm during flap side-cutting. The flap diameter was 8.0 mm, and flap thickness was set to 105 μm. Side-cut angle and hinge angle were 90°and 50° respectively. The flaps were created by laser scanning in spirals from the periphery to the center of the pupil. An excimer laser system was used in the subsequent ablation of the stromal bed with a 6.0 mm optical zone. Once the excimer ablation was completed, the flap was repositioned in a similar fashion as in routine LASIK.

Primary outcomes

  1. Schirmer I test

    Time frame: up to 1month after surgery

  2. corneal fluorescein staining

    Time frame: up to 1month after surgery

  3. noninvasive tear breakup time

    Time frame: up to 1month after surgery

  4. ocular surface disease index

    Time frame: up to 1month after surgery

  5. central corneal sensitivity

    Time frame: up to 1month after surgery

  6. tear meniscus height

    Time frame: up to 1month after surgery

  7. Interleukin-1α

    Time frame: up to 1month after surgery

  8. tumor necrosis factor-α

    Time frame: up to 1month after surgery

  9. nerve growth factor

    Time frame: up to 1month after surgery

  10. interferon-γ

    Time frame: up to 1month after surgery

  11. transforming growth factor-β1

    Time frame: up to 1month after surgery

  12. matrix metalloproteinase-9

    Time frame: up to 1month after surgery

Secondary outcomes

  1. Correlation Between Inflammatory Mediators and Ocular Surface Changes

    Time frame: up to 1month after surgery

Sponsors and collaborators

Lead sponsor

Sun Yat-sen University

Other

Registry information

Official study title

Comparison of Early Changes in Ocular Surface and Inflammatory Mediators Between Lenticule Extraction and Femtosecond Laser-assisted Laser in Situ Keratomileusis

Important dates

Study start
2015
Primary completion
2016
Study completion
2016
First posted
Sep 15, 2015
Registry last updated
Jun 14, 2016

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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