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

Comparison of Early Changes in Ocular Surface and Inflammatory Mediators 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.

Study Overview

• Status: Completed
• Conditions: Astigmatism; Myopia
• Intervention / Treatment: Procedure: lenticule extraction; Procedure: femtosecond laser-assisted laser in situ keratomileusis

Detailed Description

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.

• Study Type: Interventional
• Enrollment (Actual): 75
• Phase: Not Applicable

Contacts and Locations

Study Locations

• China
  • Hainan
    • Haikou, Hainan, China, 570311
      • Hainan Eye Hospital, Zhongshan Ophthalmic Center of Sun Yat-sen University

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 30 years (Adult)
• Accepts Healthy Volunteers: Yes
• Genders Eligible for Study: All

Description

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.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Non-Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: lenticule extraction; The patients in this group chose to receive the lenticule extraction surgery	Procedure: lenticule extraction; 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.
Experimental: FS assisted laser in situ keratomileusis; The patients in this group chose to receive the femtosecond laser-assisted laser in situ keratomileusis surgery.	Procedure: femtosecond laser-assisted laser in situ keratomileusis; 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.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Time Frame
Schirmer I test	up to 1month after surgery
corneal fluorescein staining	up to 1month after surgery
noninvasive tear breakup time	up to 1month after surgery
ocular surface disease index	up to 1month after surgery
central corneal sensitivity	up to 1month after surgery
tear meniscus height	up to 1month after surgery
Interleukin-1α	up to 1month after surgery
tumor necrosis factor-α	up to 1month after surgery
nerve growth factor	up to 1month after surgery
interferon-γ	up to 1month after surgery
transforming growth factor-β1	up to 1month after surgery
matrix metalloproteinase-9	up to 1month after surgery

Secondary Outcome Measures

Outcome Measure	Time Frame
Correlation Between Inflammatory Mediators and Ocular Surface Changes	up to 1month after surgery

Collaborators and Investigators

• Sponsor: Sun Yat-sen University
• Investigators: Principal Investigator: Xingwu Zhong, MD,PhD, Hainan Eye Hospital, Zhongshan Ophthalmic Center of Sun Yat-sen University

Study record dates

Study Major Dates

• Study Start: September 1, 2015
• Primary Completion (Actual): March 1, 2016
• Study Completion (Actual): May 1, 2016

Study Registration Dates

• First Submitted: September 13, 2015
• First Submitted That Met QC Criteria: September 14, 2015
• First Posted (Estimate): September 15, 2015

Study Record Updates

• Last Update Posted (Estimate): June 14, 2016
• Last Update Submitted That Met QC Criteria: June 13, 2016
• Last Verified: June 1, 2016

More Information

Terms related to this study

• Keywords: inflammatory mediators; tear; lenticule extraction; femtosecond laser-assisted laser in situ keratomileusis
• Additional Relevant MeSH Terms: Eye Diseases; Refractive Errors; Astigmatism
• Other Study ID Numbers: 2015-002