VisuMax Femtosecond Laser Small Incision Lenticule Extraction for the Correction of High Myopia
|The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details.|
|ClinicalTrials.gov Identifier: NCT02528123|
Recruitment Status : Active, not recruiting
First Posted : August 19, 2015
Last Update Posted : February 25, 2020
|Condition or disease||Intervention/treatment||Phase|
|Myopia Refractive Errors||Procedure: Small incision lenticule extraction Drug: Tobramycin and dexamethasone Drug: Ofloxacin Drug: Proxymetacaine 0.5% Drug: Oxybuprocaine 0.4%||Not Applicable|
Laser refractive surgery (LASIK and PRK) has been established for 25 years to treat myopia (short-sightedness). Over this time, the technology has been significantly improved to enable safe treatment of myopia up to -15D. Improvements including changing the shape of the lens of corneal tissue removed to better match the natural shape, and increasing the diameter of the applied correction to cover larger pupil sizes, have greatly reduced side-effects such as night vision glare and halos. Similarly, safety has been improved by using a laser (femtosecond laser) to create the corneal flap rather than a blade (known as a microkeratome), meaning that the cornea is reliably left with more than the safe amount of tissue.
In 2006, a new method of laser refractive surgery was introduced, small incision lenticule extraction (SMILE), which provides a minimally invasive keyhole method as it avoids the need to create a flap. In SMILE, a single laser (femtosecond laser) is used to make two curved cuts inside the cornea (without breaching the outside) that separate the lens of tissue that needs removing to focus the vision. This lens of tissue is removed in once piece (rather than evaporated as in LASIK) through a small 2mm wide tunnel to the surface.
SMILE has been used to treat short-sightedness up to -10D for more than 200,000 procedures worldwide and has been shown to achieve similar results to LASIK. However, because no flap is needed, this upper part of the cornea can also contribute strength, meaning that the cornea is stronger after SMILE than after LASIK. It is also expected that the accuracy for higher corrections using SMILE would be better than LASIK because the potential inaccuracies associated with excimer lasers (used in LASIK) are eliminated. This study will investigate the results of SMILE for myopia above -10D.
|Study Type :||Interventional (Clinical Trial)|
|Estimated Enrollment :||187 participants|
|Intervention Model:||Single Group Assignment|
|Masking:||None (Open Label)|
|Official Title:||VisuMax Femtosecond Laser Small Incision Lenticule Extraction for the Correction of High Myopia|
|Study Start Date :||April 2016|
|Estimated Primary Completion Date :||September 2020|
|Estimated Study Completion Date :||September 2020|
Experimental: Small incision lenticule extraction
Patients with high myopia will undergo a SMILE procedure to correct their refraction. Proxymetacaine 0.5% and Oxybuprocaine 0.4% will be used as anaesthetic during the procedure. Tobramycin and dexamethasone, and ofloxacin will be used four times a day for one week after the procedure.
Procedure: Small incision lenticule extraction
The VisuMax femtosecond laser is used to create two interfaces that define a refractive lenticule of stromal tissue and a 2mm wide tunnel to connect the upper layer to the corneal surface. The lenticule is manually dissected and removed through the small 2mm incision without the need to create a flap as in LASIK.
Drug: Tobramycin and dexamethasone
Tobramycin and dexamethasone (Tobradex) eye drops will be used four times a day for 1 week after the procedure
Ofloxacin (Exocin) eye drops will be used four times a day for 1 week after the procedure
Drug: Proxymetacaine 0.5%
Proxymetacaine 0.5% eye drops will be used as an anaesthetic during the procedure
Drug: Oxybuprocaine 0.4%
Oxybuprocaine 0.4% eye drops will be used as an anaesthetic during the procedure
- Variability of the refractive predicatibility (standard deviation of the postoperative spherical equivalent, adjusted relative to the intended target, after the SMILE procedure) [ Time Frame: 1 year ]Calculate the standard deviation of the postoperative spherical equivalent, adjusted relative to the intended target, after the SMILE procedure
- Efficacy of uncorrected distance visual acuity [ Time Frame: 1 year ]Measure the uncorrected distance visual acuity achieved after the SMILE procedure relative to the preoperative CDVA for all eyes where the intended target refraction was emmetropia
- Safety of corrected distance visual acuity (change in corrected distance visual acuity) [ Time Frame: 1 year ]Assess the change in corrected distance visual acuity (CDVA) before and after the SMILE procedure
- Predictability of refractive correction [ Time Frame: 1 year ]Measure the postoperative refraction and calculate the deviation from the intended target in terms of spherical equivalent. Mean, standard deviation and range will be calculated. The data will also be analyzed as a scatter plot by plotting the attempted vs achieved spherical equivalent refraction. The data will also be graphically displayed as a histogram.
- Predictability of refractive astigmatism correction [ Time Frame: 1 year ]Measure the postoperative refractive astigmatism and calculate the deviation from the intended target. Mean, standard deviation and range will be calculated. The data will also be analyzed as a scatter plot by plotting the target induced astigmatism vs the surgically induced astigmatism. The data will also be graphically displayed as a histogram.
- Stability of the spherical equivalent refraction [ Time Frame: 1 day, 1 month, 3 months, and 1 year ]Measure the postoperative refraction at 1 day, 1 month, 3 months, and 12 months after the SMILE procedure and calculate the mean and standard deviation of spherical equivalent refraction for each time point.
- Change in night vision disturbances (questionnaire) [ Time Frame: 1 year ]Provide the patient with a questionnaire to subjectively grade their quality of vision at night to assess whether this has changed after the SMILE procedure
- Change in corneal higher order aberrations [ Time Frame: 1 year ]Measure the corneal aberrations before and after the SMILE procedure using the Atlas topographer to evaluate the change in corneal aberrations due to the surgery
To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.
Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT02528123
|London Vision Clinic|
|London, United Kingdom, W1G 7LA|
|Principal Investigator:||Dan Z Reinstein, MD MA||London Vision Clinic|