Clinical trial NCT02540785: Early Changes Between Lenticule Extraction and Small-Incision Lenticule Extraction
Official title: Comparison of Early Changes in Ocular Surface and Inflammatory Mediators Between Lenticule Extraction and Small-Incision Lenticule Extraction
Study type: INTERVENTIONAL
Overall status: COMPLETED
Phase: NA
Conditions: Myopia
Astigmatism
Keywords: Refractive Surgical Procedures
small-incision lenticule extraction
lenticule extraction
inflammatory mediators
Lead sponsor: Sun Yat-sen University
Sponsor class: OTHER
First posted: 2015-09-04
Enrollment: 41
Sex: ALL
Minimum age (years): 18
Maximum age (years): 25
Standard ages: ADULT
Accepts healthy volunteers: yes
Allocation: NON_RANDOMIZED
Intervention model: PARALLEL
Primary purpose: TREATMENT

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.

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

Primary outcomes:
measure: scale of Schirmer I test
timeFrame: up to 1month after surgery
measure: scale of corneal fluorescein staining
timeFrame: up to 1month after surgery
measure: scale of noninvasive tear breakup time
timeFrame: up to 1month after surgery
measure: questionnaire of ocular surface disease index
timeFrame: up to 1month after surgery
measure: scale of central corneal sensitivity
timeFrame: up to 1month after surgery
measure: scale of tear meniscus height
timeFrame: up to 1month after surgery
measure: concentration of Interleukin-1α
timeFrame: up to 1month after surgery
measure: concentration of tumor necrosis factor-α
timeFrame: up to 1month after surgery
measure: concentration of nerve growth factor
timeFrame: up to 1month after surgery
measure: concentration of interferon-γ
timeFrame: up to 1month after surgery
measure: concentration of transforming growth factor-β1
timeFrame: up to 1month after surgery
measure: concentration of matrix metalloproteinase-9
timeFrame: up to 1month after surgery
Secondary outcomes:
measure: Correlation Between Inflammatory Mediators and Ocular Surface Changes
timeFrame: up to 1month after surgery
Other outcomes:
Locations:
Study officials:
affiliation: Zhongshan Ophthalmic Center, Sun Yat-sen University
name: Xingwu Zhong, MD PhD
role: PRINCIPAL_INVESTIGATOR
References:
citation: 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.