SMILE laser or Small-incision lenticule extraction is a new treatment and the latest in the field of keratorefractive surgery.
Small-incision lenticule extraction entails the use of the femtosecond laser to create 4 sequential cuts to form an intrastromal lenticule, which is subsequently separated from the surrounding corneal stroma to provide myopic correction.
All surgical procedures have risks.
Suction loss is one risk during SMILE laser, with an incidence ranging from 0.8% to 2.1% in large cohorts.
- Risk factors include a narrow eye openings, excessive eyelid squeezing during laser delivery, sudden eye movement, and fluid ingress between the contact glass suction ports and the cornea.
- In addition, the femtosecond-laser system used for SMILE laser is a low-pressure suction system with a longer time requirement for laser completion, in comparison to creating a LASIK flap. Combined with obscuring of the vision fixation target during the lenticule cut, there is an increased risk for suction loss during SMILE laser compared to LASIK.
- The recommendation for management of suction loss during a cap side cut entails repeating the side cut only, with a reduced size, to convert to a flap.
Inflammation known as diffuse lamellar keratitis can occur after SMILE, or LASIK. After SMILE this has been estimated to occur in 0.5% or 1/200 treated eyes.
After SMILE vision is improved immediately but can take many months to settle completely. Most people complain vision is cloudy, and this often takes several months to resolve. This is due to haziness of the residual corneal stromal bed surface, best seen with the red-reflex through a slit lamp biomicroscope.
Kerectasia is a rare progressive thinning disorder of the cornea after laser treatment. SMILE is promoted as being safer than other forms of laser but there is no evidence that this is true. In fact, multiple cases of this condition have been reported and the incidence, although rare, is probably similar.