Julian Stevens considers the impact of next-generation ocular biomechanics assessments in the clinic
Will we see intraoperative assessments of corneal biomechanics?
Intraoperative assessments will be extremely exacting from a technical point of view compared with what we’re doing now. As soon as you place a drop of topical anesthetic on the cornea, the hydration changes; as soon as you take the epithelium off or make a LASIK flap or create a SMILE lenticule, or even if you fire the femtosecond laser into the cornea, you’re going to change not just the hydration, but a whole ton of other parameters.
Once you start putting femtosecond laser pulses in, you have an amazing array of bubbles (except for Ziemer systems or the megahertz femtosecond lasers of the future) but even then, there is still a lot of light scatter coming back, and that will change the parameters. Intraoperative measurements will be highly complex. But if there’s a need, there will be clever people who will find a solution. It’s probably a “would like” rather than a “must have” right now – there are lower hanging fruits we can grab to get a better outcome.
How will next-generation corneal biomechanics assessments change femtosecond laser-assisted cataract surgery?
The evolution of the femtosecond laser for cataract surgery has been a gentle one. The slow introduction is because FS lasers are more precise – and the surgeons who using them love them – but it has been hard to find better refractive outcomes. Perioperative astigmatic treatment is one key area where there is a huge improvement using the femtosecond laser compared with manual surgery. An intrastromal FS laser application is about twice as accurate as manual surgery. So if you use one, there’s an instant improvement in outcomes – no matter how good you are as a surgeon – and the laser is more repeatable than any manual surgery.
But even with the intrastromal application of femtosecond lasers, there’s still a lot of noise in terms of variation in both delivery and outcome. Alex Day, my fellow at Moorfields Eye Hospital, and I looked at this and found that about half the variation in outcome could be ascribed to biomechanics using corneal hysteresis assessments. I can’t wait to get my hands on a BOSS scanner and some proper Brillouin scatter measurements so that I can feed that data into the nomogram, and create a smart nomogram for the individual eye, as opposed to the generic one that we have right now.
The world is moving towards mass customization, and we need to follow with our surgery. We’ve modeled and, with some biomechanical feedback, we believe that we can improve astigmatic outcomes by an immediate 50 percent. That’s huge. And that’s why I’m very excited about this.
How soon until this technology reaches the clinic?
There are a number of physical, environmental and measurement hurdles to overcome, but overcome they will be! The development of the technology will depend on very smart people working around these issues and devising solutions. But like all new technologies, the speed of adoption depends on funding – the more funding, the faster the technology will come into clinical use.
John Marshall is Professor of Ophthalmology at the Institute of Ophthalmology, University College London, London.
Julian Stevens is a Consultant Ophthalmic Surgeon, Moorfields Eye Hospital, London, UK.
Peng Shao and Amira Eltony are Harvard Medical School research fellows under the supervision of Andy Yun, Scientific Founder and board member of Intelon Optics.