Editorial from Professor Boris Malyugin – Useful devices
Patient demand has had a major effect on the power of the lenses we provide
In the past two decades lens manufacturers were being driven by clinicians in the direction of decreasing the near add of bifocal lenses from +4 to +3, then +2.5 and then even down to 1.5 dioptres. This is a trend reflecting the changes in the demands of our patients, for whom intermediate vision is becoming, at least, no less important than the near vision. This clinical finding gave birth to the new class of devices called EDOF. Rather than having distinct multiple foci, the optics of these lenses provide the extended focal zone that helps to add some intermediate vision. These devices proved to be useful, and their functionality may be further enhanced when combined with mini-monovision technology.
On the other hand, bifocal IOLs are almost completely replaced now with trifocal lenses, a concept that was pioneered about 10 years ago. Trifocal lenses now available from different manufacturers provide reasonably good optical compromise matching the demand for vision at far, near and intermediate distances. However, the true definition of “intermediate” is still a bit blurry and is a subject for further discussion.
It is now absolutely clear that utilising the complex optics we can provide our patients with high visual functions at various distances with reasonably modest optical side-effects. However, I do feel that in spite of multiple options available, we as surgeons are trying to make the selection from what we currently have rather than what the patient really needs. Sometimes the available options and patients’ expectations match perfectly. But in some cases, they do not. Computer simulation of the visual function to be achieved postoperatively is a good way to go in order to avoid unhappy patients with current multifocal technology.
Monofocal implants are the significant part of our daily clinical practice. Being able to modify the power of the lens, correct astigmatism or even add and remove multifocality to the optic already implanted inside the eye is a very exciting option. This can be achieved with various technologies, such as applying UV light or laser to modify the surface or refractive index of the implant. I do believe that sooner or later this will be the routine to enhance outcomes of lens surgery.
Despite multiple efforts, the goal of achieving functional vision with current accommodative IOL technology is yet to be achieved. Many of us are looking forward to being able to use a truly accommodative IOL in the near future. And it looks like that moment is close at hand.
- Boris Malyugin is professor of ophthalmology, Cataract and Implant Surgery Department, and chief, S.Fyodorov Microsurgery Complex, Moscow, Russia.