Myopia, Refractive Errors
Conditions
Keywords
Small incision lenticule extraction (SMILE), Femtosecond laser
Brief summary
The purpose of this study is to validate the safety and effectiveness of treating myopia (short-sightedness) higher than -10D using small incision lenticule extraction (SMILE) with the VisuMax femtosecond laser.
Detailed description
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.
Interventions
PROCEDURESmall 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.
Tobramycin and dexamethasone (Tobradex) eye drops will be used four times a day for 1 week after the procedure
DRUGOfloxacin
Ofloxacin (Exocin) eye drops will be used four times a day for 1 week after the procedure
DRUGProxymetacaine 0.5%
Proxymetacaine 0.5% eye drops will be used as an anaesthetic during the procedure
DRUGOxybuprocaine 0.4%
Oxybuprocaine 0.4% eye drops will be used as an anaesthetic during the procedure
Sponsors
London Vision Clinic
Study design
Allocation
NA
Intervention model
SINGLE_GROUP
Primary purpose
TREATMENT
Masking
NONE
Eligibility
Sex/Gender
ALL
Age
21 Years to No maximum
Healthy volunteers
Yes
Inclusion criteria
Only patients who are medically suitable for corneal refractive surgery can be included in the study. * Subjects should be 21 years of age or older * Eyes with high myopia spherical equivalent between -9.00 D up to -14.00 D, with cylinder up to 7.00 D * The corrected distance visual acuity will be 20/40 or better in each eye pre-operatively * Calculated sub-lenticule thickness (SLT) ≥220 µm * Calculated total uncut stromal thickness (TUST) ≥300 µm * Contact lens wearers must stop wearing their contact lenses at least four weeks per decade of wear before baseline measurements in case of hard contact lenses and one week before baseline measurements in case of soft contact lenses. * Patient will be able to understand the patient information and willing to sign an informed consent * Patient will be willing to comply with all follow-up visits and the respective examinations as specified in the flow-chart
Exclusion criteria
* Previous intraocular or corneal surgery of any kind on the eye being treated * Patient not being able to lie flat in a horizontal position * Patient not being able to tolerate local or topical anesthesia * Autoimmune diseases * Sicca syndrome, dry eye * Herpes viral (herpes simplex) infections * Herpes zoster * Diabetes * Pregnant or nursing women (or who are planning pregnancy during the study) * Patients with a weight of \> 135 kg * Any residual, recurrent or acute ocular disease or abnormality of the eye, e.g. * Cataract * Suspected glaucoma or an intraocular pressure \> 21 mm of Hg * Corneal disease * Corneal thinning disorder, e.g. keratoconus, * Pellucid marginal corneal degeneration * Dystrophy of the basal membrane * Corneal oedema * Exudative macular degeneration * Infection * Any residual, recurrent, or active abnormality of the cornea to be treated, e.g. * Existing corneal implant * Corneal lesion * Unstable refraction * Connective tissue disease * Dry eye
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Variability of the Refractive Predicatibility | 1 year postop | Calculate the standard deviation of the postoperative spherical equivalent, adjusted relative to the intended target, after the SMILE procedure. Analysis performed on the data from the 1 year postoperative visit. An accurate outcome is where the postoperative spherical equivalent is equal to the intended target spherical equivalent. A mean difference less than zero implies the outcome was undercorrected, whereas a mean difference greater than zero implies the outcomes was overcorrected. A smaller standard deviation represents a more accurate and more predictable outcome. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Safety of Corrected Distance Visual Acuity (Change in Corrected Distance Visual Acuity) | 1 year postop | Assess the change in corrected distance visual acuity (CDVA) before and after the SMILE procedure. Analysis performed on the data from the 1 year postoperative visit. |
| Predictability of Refractive Correction | 1 year postop | 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. Analysis performed on the data from the 1 year postoperative visit. |
| Predictability of Refractive Astigmatism Correction | 1 year postop | 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. Analysis performed on the data from the 1 year postoperative visit. |
| Efficacy of Uncorrected Distance Visual Acuity | 1 year postop | 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. Analysis performed on the data from the 1 year postoperative visit. |
| Change in Night Vision Disturbances (Questionnaire) | 1 year postop | 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. Analysis performed on the data from the 1 year postoperative visit. A Rasch scale of 0-100 was used. A score of 0 indicates no quality of vision disturbances. A score of 100 indicates severe quality of vision disturbances. The outcome is calculated as the difference between the Rasch score before and after surgery, reported as the change in Rasch score units. |
| Change in Corneal Higher Order Aberrations | 1 year postop | 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. Analysis performed on the data from the 1 year postoperative visit. |
| Stability of the Spherical Equivalent Refraction | 3 months and 1 year postop | Measure the postoperative refraction at 3 months and 12 months after the SMILE procedure and calculate the mean and standard deviation of spherical equivalent refraction for each time point. |
Countries
United Kingdom
Participant flow
Participants by arm
| Arm | Count |
|---|---|
| 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.
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.
Tobramycin and dexamethasone: Tobramycin and dexamethasone (Tobradex) eye drops will be used four times a day for 1 week after the procedure
Ofloxacin: Ofloxacin (Exocin) eye drops will be used four times a day for 1 week after the procedure
Proxymetacaine 0.5%: Proxymetacaine 0.5% eye drops will be used as an anaesthetic during the procedure
Oxybuprocaine 0.4%: Oxybuprocaine 0.4% eye drops will be used as an anaesthetic during the procedure | 114 |
| Total | 114 |
Withdrawals & dropouts
| Period | Reason | FG000 |
|---|---|---|
| Overall Study | Lost to Follow-up | 1 |
Baseline characteristics
| Characteristic | Small Incision Lenticule Extraction | — |
|---|---|---|
| Age, Categorical <=18 years | 0 Participants | — |
| Age, Categorical >=65 years | 0 Participants | — |
| Age, Categorical Between 18 and 65 years | 114 Participants | — |
| Age, Continuous | 35 years STANDARD_DEVIATION 9 | — |
| Race and Ethnicity Not Collected | — | — Participants |
| Region of Enrollment United Kingdom | 114 Participants | — |
| Sex: Female, Male Female | 67 Participants | — |
| Sex: Female, Male Male | 47 Participants | — |
Adverse events
| Event type | EG000 affected / at risk |
|---|---|
| deaths Total, all-cause mortality | 0 / 114 |
| other Total, other adverse events | 10 / 114 |
| serious Total, serious adverse events | 0 / 114 |
Outcome results
Primary
Variability of the Refractive Predicatibility
Calculate the standard deviation of the postoperative spherical equivalent, adjusted relative to the intended target, after the SMILE procedure. Analysis performed on the data from the 1 year postoperative visit. An accurate outcome is where the postoperative spherical equivalent is equal to the intended target spherical equivalent. A mean difference less than zero implies the outcome was undercorrected, whereas a mean difference greater than zero implies the outcomes was overcorrected. A smaller standard deviation represents a more accurate and more predictable outcome.
Time frame: 1 year postop
Population: Calculate the standard deviation of the postoperative spherical equivalent, adjusted relative to the intended target, after the SMILE procedure. Analysis performed on the data from the 1 year postoperative visit. An accurate outcome is where the postoperative spherical equivalent is equal to the intended target spherical equivalent. A smaller standard deviation represents a more accurate and more predictable outcome.
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Small Incision Lenticule Extraction | Variability of the Refractive Predicatibility | -0.22 Diopters | Standard Deviation 0.48 |
Secondary
Change in Corneal Higher Order Aberrations
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. Analysis performed on the data from the 1 year postoperative visit.
Time frame: 1 year postop
Population: Change in corneal spherical aberration between 3 and 12 months
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Small Incision Lenticule Extraction | Change in Corneal Higher Order Aberrations | 0.41 Microns change spherical aberration | Standard Deviation 0.16 |
Secondary
Change in Night Vision Disturbances (Questionnaire)
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. Analysis performed on the data from the 1 year postoperative visit. A Rasch scale of 0-100 was used. A score of 0 indicates no quality of vision disturbances. A score of 100 indicates severe quality of vision disturbances. The outcome is calculated as the difference between the Rasch score before and after surgery, reported as the change in Rasch score units.
Time frame: 1 year postop
Population: Change in total mean Rasch-scaled quality of vision score (including all symptoms) for bothersomeness
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Small Incision Lenticule Extraction | Change in Night Vision Disturbances (Questionnaire) | 11 scores on the Rasch scale | Standard Deviation 23 |
Secondary
Efficacy of Uncorrected Distance Visual Acuity
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. Analysis performed on the data from the 1 year postoperative visit.
Time frame: 1 year postop
Population: Percentage of eyes where the postop uncorrected distance visual acuity (UDVA) was within 1 line of preop corrected distance visual acuity (CDVA)
| Arm | Measure | Value (NUMBER) |
|---|---|---|
| Small Incision Lenticule Extraction | Efficacy of Uncorrected Distance Visual Acuity | 87 Percentage of eyes |
Secondary
Predictability of Refractive Astigmatism Correction
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. Analysis performed on the data from the 1 year postoperative visit.
Time frame: 1 year postop
Population: Percentage of eyes with refractive cylinder up to 1.00 D after SMILE
| Arm | Measure | Value (NUMBER) |
|---|---|---|
| Small Incision Lenticule Extraction | Predictability of Refractive Astigmatism Correction | 93 Percentage of eyes |
Secondary
Predictability of Refractive Correction
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. Analysis performed on the data from the 1 year postoperative visit.
Time frame: 1 year postop
Population: Percentage of eyes with spherical equivalent refraction within +/- 1.00 D of the intended target
| Arm | Measure | Value (NUMBER) |
|---|---|---|
| Small Incision Lenticule Extraction | Predictability of Refractive Correction | 96 Percentage of eyes |
Secondary
Safety of Corrected Distance Visual Acuity (Change in Corrected Distance Visual Acuity)
Assess the change in corrected distance visual acuity (CDVA) before and after the SMILE procedure. Analysis performed on the data from the 1 year postoperative visit.
Time frame: 1 year postop
Population: Percentage of eyes with loss of 2 or more lines of corrected distance visual acuity (CDVA)
| Arm | Measure | Value (NUMBER) |
|---|---|---|
| Small Incision Lenticule Extraction | Safety of Corrected Distance Visual Acuity (Change in Corrected Distance Visual Acuity) | 0 Percentage of eyes |
Secondary
Stability of the Spherical Equivalent Refraction
Measure the postoperative refraction at 3 months and 12 months after the SMILE procedure and calculate the mean and standard deviation of spherical equivalent refraction for each time point.
Time frame: 3 months and 1 year postop
Population: Percentage of eyes with change in SEQ more than 0.50 D between 3 and 12 months
| Arm | Measure | Value (NUMBER) |
|---|---|---|
| Small Incision Lenticule Extraction | Stability of the Spherical Equivalent Refraction | 8 Percentage of eyes |