A EUREQUO Moment

• For issues like manual vs. femtosecond laser-assisted cataract surgery, registries are vital because masked trials are nearly impossible
  
• The four-year-old EUREQUO database maintained by the ESCRS contains information on up to 1.5 million cataract surgeries
  
• That data was recently mined for a precisely matched case–control study on manual phacoemulsification vs. FLACS
  
• The results highlighted the benefits and drawbacks of each procedure, concluding that, at the moment, neither one definitively outperforms the other

It’s almost eight years since Zoltán Nagy performed the first femtosecond laser-assisted capsulotomy in a human patient, ushering in the age of FLACS – femtosecond laser-assisted cataract surgery (1). Since then, the number of FLACS procedures performed has grown year on year – but the percentage of cataract surgeons adopting the laser has remained stubbornly in the single digits (2).

The principal attraction of femtosecond lasers is that they produce reproducibly round capsulotomies at exactly the size specified by the surgeon (3), something that’s believed to be crucial for achieving the best possible outcomes in patients receiving “premium” intraocular lenses (IOLs). Many surgeons talk of an element of keeping your hand in – when performing continuous curvilinear capsulorhexes (CCCs), a femtosecond laser should mean you can perform a capsulotomy that’s more perfectly circular and well-centered than “the high volume surgeon down the street” can do with his or her hands. Given that there’s a certain “Goldilocks” diameter to capsulorhexes – too small risks anterior capsule fibrosis and hyperopic IOL shifts, whereas too big risks lens tilt/decentration, posterior capsule opacification, and myopic postoperative error (4) – you can see the attraction of programming in the ’rhexis on the screen, then just clicking to have it performed for you. The second killer feature on offer is that the laser can pre-fragment the patient’s lens, something that should make phacoemulsification easier and faster than manual phacoemulsification; also, as less ultrasound energy is required, fewer endothelial cells should be lost (4). There’s also the ability to make corneal relaxing incisions to correct astigmatism with the laser. What’s not to like?

Part of the reason why the FLACS adoption rate today is still under 10 percent is cost. A typical femtosecond laser platform can easily cost €500,000 – but beyond that, even at face value, femtosecond lasers don’t represent a total panacea for cataract surgeons. Laser capsulotomies take longer to perform than manual capsulorhexes (slowing throughput), the capsulotomy isn’t as strong, and early femtosecond lasers gained a certain reputation. Although some of the issues early femtosecond laser users experienced – like the occasional incomplete capsulotomies and the fact that anterior capsular tears seemed to occur significantly more frequently in patients who underwent FLACS (5) – are far less of a problem with the newest femtosecond laser platforms, it is going to take a while to erase those doubts. There’s also a learning curve, which is usually associated with an increased rate of surgical complications; the docking and use of the laser introduces unique risks; and femtosecond lasers are still not indicated for use in patients with small pupils (6). Although FLACS surgery is associated with less corneal endothelial cell damage than conventional cataract surgery (7), there’s some concern about the fact that the femtosecond laser still introduces energy (and heat) into the eye, which may affect intraocular structures like corneal endothelial cells and the iris (8). If we return to the “keeping your hand in” proposition above; that’s fine until a patient appears with something like small pupil – a contraindication for femtosecond laser use. So if you're “out of practice”…

In terms of anything approaching a clinical trial of man vs. machine in cataract surgery, there have been a number of evaluations (reviewed in [4]) – but all have been beset with a number of limitations: small patient numbers, no possibility of masking the procedures used, and often, a limited set of outcomes being assessed. In any event, the literature to date (albeit with the limitations listed above) has failed to demonstrate any significant differences in visual and safety outcomes between FLACS and manual CCC/ standard phaco cataract surgery (4).

“The nature of registry data is that it comes from the real world and it should reflect the reality of clinical practice.”

But there’s another way of getting robust clinical evidence of the safety and efficacy of manual vs. FLACS procedures: a registry of real-world patients and their real-world outcomes. Clinical evaluations tend to be regimented in their design and execution, with specific inclusion and exclusion criteria. The nature of registry data is that it comes from the real world and it should reflect the reality of clinical practice. However, a registry’s usefulness is determined by the amount of information it contains – the more, the better – and that means it needs to be run under the auspices of an international organization with the membership, funds and infrastructure to do it properly. And in the case of FLACS, the organization that stepped up was the European Society of Cataract and Refractive Surgeons (ESCRS). We interviewed ESCRS past president and current board member Peter Barry about their endeavor: EUREQUO.