Innovations in cataract surgery
Technology evolves to solve remaining challenges
The evolution of modern cataract surgery can be seen as a long history of creative, sometimes iconoclastic innovation. In many cases this innovative process meets resistance from established authorities until the worth of a new idea can be proven to improve on existing procedures.
With 50 years of experience since the debut of phacoemulsification and small-incision IOLs, cataract surgery could be said to have reached maturity. Or is it entering another new era?
“Currently, I do not see THE thundering miracle innovation – but I see a number of developments that I find interesting: refractive index manipulation, exchange of only an anterior part of an IOL for later adjustment, rhexis-fixated optics for precise and stable positioning of toric lenses – and, of course, the yet unfulfilled dream of an accommodating IOL. Progress happens incrementally. A big step in hindsight always is composed of many little steps,” Thomas Neuhann MD, Medical Director of the Laser Eye Centre, Munich, told EuroTimes.
CAPSULORHEXIS PAST AND FUTURE
The capsulorhexis is the starting point for the cataract surgery. Early methods used various instruments and tearing patterns. This finally gave way to the familiar continuous curvilinear capsulorhexis, co-credited to innovators Dr Neuhann and Dr Howard Gimbel.
Since that time the femtosecond laser entered the arena promising a well-centred perfect capsulotomy for every procedure. However, femtosecond lasers are quite expensive.
“The femto-lasers are getting better at producing continuous edges – but are not quite there yet – they really still produce ‘micro-can-openers’. Yes, they are obviously 100% circular – but ‘it is really not about circularity – it’s about continuity’, as Howard Gimbel so truly stated. At this time and stage of development, I cannot find it yet an improvement that has relevant advantages over a manual rhexis, not least also under a cost-benefit aspect. But we’ll see what the future brings,” said Dr Neuhann.
The search for cost-sensitive options has prompted the development of a number of interesting alternatives. One of these, the CAPSULaser (Excel-Lens), received the CE mark in 2017. It is a thermal laser that attaches to a standard operating microscope.
Another option, the Zepto precision pulse capsulotomy system (Mynosys), has received the CE mark and US FDA 510K approval. That system uses a disposable handpiece, microsecond electric pulses and suction to create circular capsulotomies.
“I find every new development interesting, worth trying out. Both of these show interesting promises in their principles – we’ll have to see how they perform in large series, in complicated cases and in comparison with the manual rhexis,” commented Dr Neuhann.
IOL developers are responding to the remaining challenges of cataract surgery with an unprecedented array of new ideas. The search for better multifocal IOLs is driven by the desire to reduce the nagging problems with glare, halo and patient dissatisfaction associated with the first generation of this class of lens.
Trifocal IOLs now gaining ground include the FineVision (PhysIOL), the AcrySof IQ PanOptix and the Zeiss AT LISA. Recent clinical results suggest that the lenses provide good visual acuity at near, intermediate and far distances, with fewer adverse optical effects. Other trifocals include the Alsafit (Alsanza) and Acriva Reviol (VSY Biotech).
Extended depth of focus (EDOF) lenses are another interesting development in the multifocal IOL field. The first to market was the Tecnis Symfony (J&J Vision), reportedly producing good vision at a range of distances, particularly for near vision. The AT LARA (Zeiss) also arrived on the market recently. In clinical trials that lens provided a good range of vision, particularly in the intermediate range.
More recently, monofocal IOLs based on the pinhole principle to increase depth of focus have come on the market. This includes the IC-8 IOL (AcuFocus), a single-piece hydrophobic monofocal IOL, and the XtraFocus pinhole implant (Morcher), an acrylic, small-aperture sulcus IOL.
The dream of a truly accommodating IOL is getting closer to reality thanks to several innovative products now in clinical trials. The FluidVision (PowerVision) changes accommodative power by increasing and decreasing the quantity of fluid within the optic. The Juvene (LensGen) is a two-lens modular IOL made of a monofocal base lens into which a fluid-optic accommodating component that changes curvature is placed. Another novel lens in development is the Sapphire IOL (Elenza), an electronically controlled, remotely programmable, customisable IOL.
Sulcus-implanted accommodative IOLs are also in development. One of these is the Lumina lens (Akkolens/Oculentis), which produces accommodation via two optical elements shifting in a plane perpendicular to the optical axis. Another is the Dynacurve IOL (NuLens), which uses the movement of the ciliary muscles to change the curvature of the optic. Both are in the early clinical stages.
FINALISING THE FINAL RESULT
Even with perfect surgical technique and the best IOL available, the final result of cataract surgery doesn’t always match the intended result. Now it seems the final result may not be final at all, but could be adjusted after the surgery has been completed. A small company in California has developed a femtosecond machine it calls the Perfector2 (Perfect Lens), which it says can be used to increase or decrease the dioptres of an implanted lens, change a multifocal into a monofocal or create a multifocal from a monofocal. The product is now in the animal testing stages.
Thomas Neuhann: firstname.lastname@example.org