Early Changes Between Lenticule Extraction and Small-Incision Lenticule Extraction

NCT ID: NCT02540785

Last Updated: 2016-11-28

Basic Information

• Recruitment Status: COMPLETED
• Clinical Phase: NA
• Total Enrollment: 41 participants
• Study Classification: INTERVENTIONAL
• Study Start Date: 2014-04-30
• Study Completion Date: 2014-12-31

Brief 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.

Detailed 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For both FLEx and SMILE, stromal ablation has been replaced by refractive lenticule removal.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.

Conditions

Myopia; Astigmatism

Keywords

Refractive Surgical Procedures; small-incision lenticule extraction; lenticule extraction; inflammatory mediators

Study Design

• Allocation Method: NON_RANDOMIZED
• Intervention Model: PARALLEL
• Primary Study Purpose: TREATMENT
• Blinding Strategy: NONE

Study Groups

lenticule extraction

The patients in this group chose to receive the lenticule extraction surgery.

Group Type: EXPERIMENTAL

lenticule extraction

Intervention Type: 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

small-incision lenticule extraction

The patients in this group chose to receive the small-incision lenticule extraction surgery.

Group Type: EXPERIMENTAL

small-incision lenticule extraction

Intervention Type: 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), make a small incision

Interventions

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

Intervention Type: PROCEDURE

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

Intervention Type: PROCEDURE

Other Intervention Names

0.3% tobramycin/dexamethasone (TobraDex, Alcon); 0.5% levofloxacin (Cravit, Santen); sodium hyaluronate (HYCOSAN,URSAPHARM Arzneimittel GmbH); 0.3% tobramycin/dexamethasone (TobraDex, Alcon); 0.5% levofloxacin (Cravit, Santen); sodium hyaluronate (HYCOSAN,URSAPHARM Arzneimittel GmbH)

Eligibility Criteria

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

• Minimum Eligible Age: 18 Years
• Maximum Eligible Age: 25 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: Yes

Sponsors

Sun Yat-sen University

OTHER

Sponsor Role: lead

Responsible Party

Xingwu Zhong, MD PhD

Professor

Responsibility Role: PRINCIPAL_INVESTIGATOR

Principal Investigators

Xingwu Zhong, MD PhD

Role: PRINCIPAL_INVESTIGATOR

Zhongshan Ophthalmic Center, Sun Yat-sen University

References

Zhang C, Ding H, He M, Liu L, Liu L, Li G, Niu B, Zhong X. Comparison of Early Changes in Ocular Surface and Inflammatory Mediators between Femtosecond Lenticule Extraction and Small-Incision Lenticule Extraction. PLoS One. 2016 Mar 3;11(3):e0149503. doi: 10.1371/journal.pone.0149503. eCollection 2016.

Reference Type: DERIVED

PMID: 26937680 (View on PubMed)

Other Identifiers

2014-005

Identifier Type: -

Identifier Source: org_study_id