SMILE v femto-LASIK
New, less invasive technology faces off against proven results, greater versatility
Sri Ganesh, MBBS, BS (Ophth), DNB
When Sri Ganesh, MBBS, BS (Ophth), DNB, received one of the first lasers for small-incision lenticule extraction (SMILE®) corneal refractive surgery in 2012, he was doing about 750 femto-LASIK procedures, annually with good results and happy patients. “So why should I change?” he asked.
To answer, Dr Ganesh conducted a prospective, randomised study comparing 50 LASIK with 50 SMILE patients at Nethradhama Super Specialty Eye Hospital, Bangalore, India.
“SMILE has since been my preferred corneal refractive procedure,” he told the 36th Congress of the ESCRS in Vienna in a debate session.
In that early study, 96% of SMILE patients achieved 20/20 or better uncorrected with 12% at 20/16 or better, compared with 88% and 4% respectively for femto-LASIK three months after surgery, Dr Ganesh reported. Induced higher-order aberrations were nearly double in the femto-LASIK group, leading to less glare, and better night vision in the SMILE group. Tear film break-up time was significantly shorter and tear osmolarity significantly higher in the LASIK group, and patient-reported comfort, including post-op pain and dry eye, was better in the SMILE group. All of these differences were statistically significant (Ganesh S, Gupta R. JRS 2013).
In the six years since, Dr Ganesh’s SMILE outcomes have only improved. In more than 7,000 cases, 98.4% have achieved at least 20/20 uncorrected, with 68% better than 20/20. No eye has had complications such as haze, deep lamellar or infectious keratitis, or lost more than two lines of corrected vision. Just 10 eyes have required enhancement. Other studies suggest SMILE is stable long term, regressing less than 0.5 dioptres over five years (Blum M et al. BJO 2016;100(9)).
“SMILE has proven popular with patients, who are willing to pay more for it,” Dr Ganesh said. “Minimally invasive surgery is something patients understand and prefer.”
With a 2.0mm incision for SMILE vs 20mm for LASIK, SMILE patients have less pain, do not require eye shields at night and there are no restrictions on showering or activities the day after surgery, he noted.
SMILE is also a financial winner, Dr Ganesh said. Where 700 or so LASIK procedures generated about €2 million annually before 2012, in 2017 Dr Ganesh’s centre did 2,150 SMILEs, generating more than €15 million. The increased revenue more than offset the higher cost of the laser and consumables, Dr Ganesh said.
Dr Ganesh allowed that SMILE has significant limitations compared with LASIK. There is currently no automatic adjustment for cyclotorsion, which his research suggests could improve outcomes. SMILE has not yet been approved for hyperopic corrections, though Dr Ganesh’s research suggests it will be highly effective and believes it will be available soon. Enhancements are also challenging without converting to PRK or LASIK, though SMILE enhancements are possible and becoming more available.
Terry Kim MD
Still, SMILE has a long way to go to match the versatility and proven track record of LASIK, said Terry Kim MD, Professor of Ophthalmology, Duke University School of Medicine; Chief, Cornea and External Disease Division and Director, Refractive Surgery Service at Duke University Eye Center in Durham, North Carolina. He cited the work of the LASIK Task Force, a joint effort of the US FDA, AAO, ASCRS and NEI. Their international review found LASIK to be one of the most successful elective surgeries of any kind, with more than 95% satisfaction in 309 published studies (Solomon et al. Ophthalmology. 2009;116(4):691-701.)
LASIK also has a much wider treatment range, including hyperopic and mixed astigmatism, and can be customised to enhance prior corneal refractive and cataract surgery. Indeed, femtosecond laser-assisted cataract surgery platforms are now offering LASIK flap capabilities, suggesting the technology is far from played out, Dr Kim said.
“LASIK … has a long, proven track record and is one of the most studied procedures in the world. Based on the data we have to date, we can conclude that SMILE may not necessarily be better than LASIK,” Dr Kim said.
Sri Ganesh: firstname.lastname@example.org
Terry Kim: email@example.com