Truly accommodating IOL offers promising results
Ophthalmologists have been searching for effective ways to address presbyopia for many decades, particularly with cataract surgery.
We started off doing monovision with one eye set for distance vision and the other for near or intermediate vision by targeting myopia. This works but comes at a compromise of reduced depth perception, so there was a push to multifocal IOL designs. These were originally refractive in design, which worked, but produced many unwanted visual side effects. The next evolution was diffractive designs and eventually trifocal optics, which give better vision but still come with the limitations of splitting the incoming light.
Most recently, we have embraced extended depth of focus (EDOF) designs, which limit some of the dysphotopsias but produce less range of vision. To address that, we are moving back to doing a smaller degree of monovision with these EDOF IOLs. It seems strange that after so many years we are seemingly back to where we started with implementing monovision. Perhaps a better solution is to actually restore accommodation with novel IOL designs.
Nearly 8 years ago, in early 2015, I was the first surgeon to implant the LensGen Juvene in trials that were done outside the U.S. The idea behind the Juvene is to change the power of the IOL by means of a curvature change to the front optic. Previous attempts to create an accommodating IOL by having anterior movement of the optic were limited because a 1-mm shift of the optic will produce about 1 D of power change, and that could be far lower in a larger eye with a lower-power IOL. The Juvene IOL has two optics: a base lens, which is posterior, and a power lens, which is fluid filled and anterior. The curvature change in the anterior power lens is capable of producing a reasonable accommodative amplitude to restore near vision.
The lens design has continued to evolve over the years, and most recently, the Grail study results were released with 24-month data. Patients were distance corrected so that the effect of residual myopia would not confound the results. Monocular data showed 3.5 D of accommodative range, from approximately +1.5 D to –2 D at 20/40 or better visual acuity (Figure 1). These eyes achieved 20/20 distance vision, 20/32 intermediate vision and 20/40 near vision, which is functional for nearly all daily visual activities.
These results show a wider visual range than the Alcon Vivity EDOF IOL, which was about 2.7 D and double the range compared with the Johnson & Johnson Vision Tecnis, a high-quality monofocal IOL. The goal of the Juvene lens is to provide a wide range of vision without spectacles while maintaining the highest levels of visual quality by avoiding light-splitting designs. Separate testing showed that the visual quality and contrast produced by the Juvene were the same as the Tecnis IOL.
Binocular defocus curves, also distance corrected, of the Juvene IOL show the benefit of binocular summation (Figure 2). While the monocular testing showed a total of 3.5 D of range, with both eyes distance corrected, this improved to 4.5 D of total range, from about +2 D to –2.5 D. This gives 20/16 distance vision, 20/25 intermediate vision and 20/40 near vision. If the focal point of one or both eyes is adjusted, this can be shifted to further improve the near vision acuity.
The Juvene IOL is designed to completely fill the capsular bag, the same as a natural human crystalline lens. By keeping the capsular bag open and preventing contraction and fibrosis, there are some distinct benefits. Because the capsular bag does not collapse, the effective lens position is stable and does not shift over time, thereby producing more predictable refractive results. This also stops tilt or rotation of the IOL, which is helpful to address astigmatism with toric optic designs. In addition, there is no vitreous shift in the postop period because the capsular bag volume does not decrease. This may produce less stress on the retina and give more stability to the vitreous (figure 3).
The most important benefit of completely filling the capsular bag is prevention of posterior capsule opacification. In all of the studies performed by LensGen, there was a zero incidence of posterior capsule opacification even coming on 5 years postop. Should a YAG laser capsulotomy be required, it can be performed without issues, but in all likelihood, there should be no need.
The Juvene is currently undergoing FDA trials, and it is not otherwise available for use by U.S. surgeons. While it is hard to predict the FDA approval process, I am confident that ophthalmologists will have many accommodating IOL options in the future so that we can restore youthful and natural vision to our patients.