Early Changes Between Lenticule Extraction and Small-Incision Lenticule Extraction

Myopia Clinical Trial

Official title:

Comparison of Early Changes in Ocular Surface and Inflammatory Mediators Between Lenticule Extraction and Small-Incision Lenticule Extraction

Clinical Trial Details — Status: Completed

Administrative data

• NCT number: NCT02540785
• Other study ID #: 2014-005
• Status: Completed
• Phase: N/A
• First received: August 31, 2015
• Last updated: November 24, 2016
• Start date: April 2014
• Est. completion date: December 2014

Study information

• Verified date: November 2016
• Source: Sun Yat-sen University
• Contact: n/a
• Is FDA regulated: No
• Health authority: China: National Health and Family Planning Commission
• Study type: Interventional

Clinical Trial Summary

The aim is to evaluate the short-term changes in ocular surface measures and tear inflammatory mediators after lenticule extraction (FLEx) and small-incision lenticule extraction (SMILE) procedures.

Description:

The use of femtosecond (FS) laser has become one of the most significant technological advancements in refractive surgery. A breakthrough FS laser-assisted myopic and myopic astigmatic correction procedure can now be performed using a prototype femtosecond system. This first all-in-one FS-laser system was designed to perform the refractive lenticule extraction (ReLEx) procedures, femtosecond lenticule extraction (FLEx) and small-incision lenticule extraction (SMILE). In FLEx, a corneal flap is created by the FS laser (similar to LASIK) and lifted, allowing lenticule removal. For SMILE, a truly without flap procedure, only a small—2-4mm— incision is made, through which the lenticule is removed.

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.

For both FLEx and SMILE, stromal ablation has been replaced by refractive lenticule removal. In terms of corneal flap formation, FLEx still requires an epithelial-stromal flap, while SMILE employs only a small incision to extract the lenticule. Hence, the investigators hypothesize that SMILE will have less effect on patients' ocular surface markers and inflammatory mediators, compared to FLEx. In support of this hypothesis, previous studies have reported that more damage to the sub-basal nerve plexus of the cornea and more changes in ocular surface evaluations were found after FLEx than after SMILE. In this study, the investigators have focused on postoperative changes to tear inflammatory mediators and the relationship of FLEx and SMILE to dry eye.

Recruitment information / eligibility

• Status: Completed
• Enrollment: 41
• Est. completion date: December 2014
• Est. primary completion date: December 2014
• Accepts healthy volunteers: Accepts Healthy Volunteers
• Gender: Both
• Age group: 18 Years to 25 Years

Eligibility

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, verified with an Atlas topographer; 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 Design

Allocation: Non-Randomized, Intervention Model: Parallel Assignment, Masking: Open Label, Primary Purpose: Treatment

Related Conditions & MeSH terms

• Astigmatism
• Myopia

Intervention

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
• small-incision 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), make a small incision

Locations

Country	Name	City	State
n/a

Sponsors (1)

Lead Sponsor	Collaborator
Sun Yat-sen University

Outcome

Type	Measure	Description	Time frame	Safety issue
Primary	scale of Schirmer I test		up to 1month after surgery	No
Primary	scale of corneal fluorescein staining		up to 1month after surgery	No
Primary	scale of noninvasive tear breakup time		up to 1month after surgery	No
Primary	questionnaire of ocular surface disease index		up to 1month after surgery	No
Primary	scale of central corneal sensitivity		up to 1month after surgery	No
Primary	scale of tear meniscus height		up to 1month after surgery	No
Primary	concentration of Interleukin-1a		up to 1month after surgery	No
Primary	concentration of tumor necrosis factor-a		up to 1month after surgery	No
Primary	concentration of nerve growth factor		up to 1month after surgery	No
Primary	concentration of interferon-?		up to 1month after surgery	No
Primary	concentration of transforming growth factor-ß1		up to 1month after surgery	No
Primary	concentration of matrix metalloproteinase-9		up to 1month after surgery	No
Secondary	Correlation Between Inflammatory Mediators and Ocular Surface Changes		up to 1month after surgery	No