SBK: what's in a name?

Refractive surgery has come a long way since the first lamellar refractive surgeries were performed decades ago. Through continuous fine-tuning and evolution, LASIK has become today's dominant refractive procedure. However, as with all medical procedures, there is always room for improvement.

Across the globe, refractive surgeons continue to question LASIK's superiority over surface ablation procedures. LASIK advocates refer to the pain, haze and longer recovery associated with surface procedures as being their reasons for choosing LASIK, whilst supporters of PRK emphasize complications relating to biomechanical weakening of the cornea, dry eye and even ectasia following standard LASIK flap creation.

Both techniques clearly have their own advantages but is there a way to reach a compromise? In other words, does a procedure exist that can combine the fast visual recovery, low pain and haze levels associated with LASIK, with the provision of corneal biomechanical stability afforded by PRK?

"Some years ago, I was having a discussion with John Marshall from the UK and Stephen Slade from the US when we came to the realization that we weren't using the femtosecond laser to its full potential. We were simply trying to duplicate microkeratome-induced flaps with a laser," Dr Durrie said. It was this thought that led the colleagues to consider how they might take full advantage of the femtosecond's capabilities.

The team began by studying different flap thicknesses and the accuracy of the femtosecond laser using high-resolution ultrasound and OCT. "We found the laser to be extremely accurate, with the thickness only varying by around 4 to 5 μm across the flap from individual patients. This was an important breakthrough," enthused Dr Durrie.

Meanwhile, Dr Marshall's work on the biomechanics of the cornea confirmed that a thinner flap would be better for the cornea in the long-term because it involves the cutting of less fibres and nerves.

"When Stephen Slade and I began to look at the clinical results with this technique, we felt that they were sufficiently different from those obtained with the original femtosecond LASIK flaps and the blade-like LASIK flaps to warrant a new name," said Dr Durrie.

This new procedure involved the creation of a flap just below Bowman's membrane and hence the name, sub-Bowman's keratomileusis or SBK was born.

Does it deserve a new name?

'Why call it something different?' has been a question on most people's lips. Is it really deserving of a new name?

Dr Durrie feels that the excellent results seen with the procedure so far, when compared with PRK or LASIK, merit the use of a new name. "I think it's important to give it a new name, particularly from a patient point of view. LASIK has been around since 1991 and during this time it has changed dramatically; it is much safer, more accurate and is an all round better procedure. Now the next stage in the evolution of this procedure is taking us towards the thinner flap and the data we are getting are sufficiently different to allow us to tell our patients that a new procedure has arrived," said Dr Durrie.

"I haven't used the LASIK term in my clinic for a couple of years now, I always use SBK. My patients feel that we have now moved beyond LASIK and on to the next procedure. Although I do explain to them that it's not a totally new procedure and that it is the next evolution in keratomileusis, which has been around for 60 years, patients have been generally accepting," added Dr Durrie.

Dr Durrie admitted that there has been some resistance to SBK from the ophthalmic community, either from those who have been quite happy with the traditional technique, or those who understandably do not want to make such a large financial investment in femtosecond technology, or from those who have been performing this procedure for years and so do not feel a new name is entirely necessary.