While cataract surgery continues to evolve with smaller incisions, better viscoelastics, astigmatic and presbyopic corrective lenses, it becomes more difficult to make substantial improvements in outcomes. Nevertheless, several companies have developed technologies that raise the bar. These lenses, if not already available in other countries, will likely be approved abroad before coming to the US. Even so, we should expect to see several of these in our ASCs shortly.
The most appropriate new lens to discuss first would be the aptly named NuLens. This lens differs from other posterior chamber intraocular lenses in that it is meant to be placed in the sulcus. The optic consists of a piston and soft gel material which "trampolines" against the capsular diaphragm with accommodation. Animal studies initially revealed about 40 diopters of accommodation, which at one year post-operatively appears to settle between 5 and 10 diopters. Unfortunately the device requires a large incision or insertion, which will hopefully be redesigned before its US approval.
One of the major drawbacks of the toric intraocular lenses currently available is that they can only correct a limited amount of astigmatism. Fortunately, Alcon has developed toric lenses that correct for much greater amounts of cylinder. These lenses are currently undergoing trial and will likely be available soon.
While toric lenses have been terrific for correcting astigmatism, they cannot provide presbyopic correction for individuals unless monovision is targeted. Multifocal lenses, on the other hand provide spectacle independence but cannot correct for astigmatism, requiring surgeons to perform limbal relaxing incisions or laser vision correction post-operatively. While not yet available, in the future Alcon will release their toric aspheric Restor intraocular lens. By providing improved uncorrected refractive error, so critical to this lens technology, we should expect even greater patient satisfaction.
The tetraflex is an accommodating lens currently being studied in the US. Similar to the Crystalens, it is meant to vault anteriorly and posteriorly with accommodative effort. Some of the more recent data from England suggest that 95.6% of patients achieve greater than 1 diopter of accommodation, 69.2% of patients achieve > 2D, and 19.8% achieve greater than 3D.
Finally, what may become the most accurate lens for surgeons is Calhoun's light adjustable lens. The lens material contains photosensitive silicone subunits, referred to as macromers. A digital light delivery device is then used 2-4 weeks postoperatively which causes migration of these macromers and refractive change. This can be used to treat myopia, hyperopia, and astigmatism. Additionally, the laser can be repeated to fine tune uncorrected vision even more.
Ultimately, our lens technology continues to evolve at an exponential rate. As scientific advances such as these newer lenses continue to be released we become very close to being able to offer our patients truly "perfect vision".