Small incision lenticule extraction (SMILE) for high myopia
Research type
Research Study
Full title
VisuMax femtosecond laser small incision lenticule extraction (SMILE) for the correction of high myopia.
IRAS ID
140276
Contact name
Dan Reinstein
Contact email
Sponsor organisation
London Vision Clinic
Clinicaltrials.gov Identifier
Duration of Study in the UK
3 years, 0 months, 1 days
Research summary
Summary of Research
Corneal laser eye surgery (LASIK and PRK) has been established for over 20 years to treat myopia (short-sightedness) and astigmatism, including very high myopia (above -10.00D). In LASIK, which is the most popular method of correcting vision, a thin shaving of tissue is cut from the corneal surface with an infrared (femtosecond) laser and lifted, while the ultraviolet (excimer) laser evaporates tissue from the exposed bed.Summary of Results
In this study, excellent outcomes were achieved for the treatment of high myopia (short-sightedness) of -9.00 D up to ‐13.00 D using small incision lenticule extraction (SMILE). Refractive and visual outcomes were the same or better than those achieved by laser in-situ keratomileusis (LASIK). In particular, 87% of eyes achieved uncorrected distance visual acuity (UDVA) within 1 line or better of their corrected distance visual acuity (CDVA) before surgery. The accuracy of the refractive correct (spherical equivalent) was within ±0.50 D in 66% and within ±1.00 D in 96% of eyes. No eyes lost 2 or more lines of CDVA.The main study endpoint was the comparison of refractive scatter (variance) between SMILE and previously published LASIK series. The standard deviation of refractive accuracy was 0.48 D in the SMILE group compared to 0.68 D in the LASIK group, representing a statistically significant difference. This result provides supporting evidence that the cornea is more biomechanically predictable with SMILE compared to LASIK in the treatment of high myopia between ‐9.00 D and ‐13.00 D.
Patient satisfaction and independence from glasses were very high. The compromise was a slightly increased risk of night vision disturbances. However, this was balanced by the benefit of correcting very high myopia.
In 2007, an infrared laser accurate enough to make two curved cuts inside the cornea to treat myopia was introduced. SMILE (Small Incision Lenticule Extraction) is a procedure where two curved cuts are made, and the lens of tissue (called lenticule)is removed in one piece through a small 2-mm wide tunnel, therefore providing a keyhole type procedure .
SMILE is CE approved to treat myopia up to -10.00D and astigmatism up to -5.00D with a maximum spherical equivalent of -12.50D.
In this study, we are going to use the SMILE procedure to treat a higher range of myopia, up to -14D and up to -7D of astigmatism, with a maximum spherical equivalent of -14.00D and aim to demonstrate equal safety and efficacy to that of LASIK.
A second aim of this study is to establish appropriate tissue removal safety parameters for SMILE surgery. The current tissue removal safety parameters for SMILE were set to be the same as that of LASIK, and only based on the untouched tissue reserve below where the lenticule is removed. In this study we propose that in SMILE, the tissue reserve should also take into account the uncut tissue above where the lenticule is removed. Based on this assumption, the minimum thickness of the uncut cornea under the lenticule can safely be lower for SMILE than for LASIK.
The study will take place at the London Vision Clinic and patients will be attending follow-up visits for at least 1 year after surgery.REC name
West Midlands - South Birmingham Research Ethics Committee
REC reference
15/WM/0348
Date of REC Opinion
7 Mar 2016
REC opinion
Further Information Favourable Opinion