While intraocular lens technology continues to advance similar to the rate of computers, we have been able to meet our patients' ever-increasing expectations. In this article, I review some of the changes that occurred in lens use in 2011.
Monofocal Lenses: In the category of monofocal lenses, aspheric intraocular lenses have surged in popularity. Touting benefits such as improved night driving and increased depth of focus, ophthalmologists have come to select these more and more for their standard IOL cases. Which lens is the best, however, is still up for debate. While some surgeons prefer lenses with the most negative spherical aberration to achieve zero abberations (example: Abbott Tecnis ZCBOO), others feel leaving the patient with a slight amount of positive spherical aberration will improve depth of focus (using lenses such as Alcon SN60WF). Centration plays a big role with correcting aberration, and for those who believe IOL centration cannot be truly perfect, they prefer zero aspheric lenses such as the Bausch & Lomb AO60/MI60L series. If that weren’t enough, some surgeons prefer the Lenstec series of IOLs, as they come in quarter diopter steps and theoretically should increase post-operative refractive accuracy. Of course with the upsides come downsides, and whether they are in the form of negative dysphotopsias, glistenings, or increased phimotic reaction of the bag, they can still be problematic. Fortunately these lenses all perform at an exceptional level, and well controlled trials will teach us which one is truly the best. My personal experience with these lenses have ranged:
- Abbott ZCB00: A lens that centers well, unfortunately I have only been able to implant it via 2.4 mm incision by using it with the Alcon Monarch D cartridge. This has worked well for me with the exception of higher (>25D) power lenses that sometimes split open the cartridge. Abbott has released their own new Platinum series injector which reports to have solved these issues.
- Alcon SN60WF: A lens that injects and centers well. Surgeons must be cautious watching the haptics unfold and well as during irrigation/aspiration to ensure one haptic does not pop up into the sulcus at the end of the case. Glistenings, while present in many cases, have only been visually significant in a small number of cases.
- B&L MI60L: A hydrophilic lens which is perhaps the easiest to insert, it seems to carry a greater risk of post-operative inflammation including early PCO, iritis, CME, and capsule contraction with IOL shift. These experiences have led me to greatly prefer the earlier thicker model AO60 over the MI60L.
- Hoya PC-60AD: A 3 piece aspheric IOL that I have stopped using since a few cases of haptics either cutting through the posterior capsule on injection or snapping off the optic.
- Lenstec Softec HD: Made from the same material as the MI60L, it appears to share the inherent risks of post-operative capsule contraction and IOL shift.
- Staar: A collamer plate haptic IOL, it carries the same risks of decentration post-YAG.
Toric lenses: With the approval of Alcon's T6-T9 series, much greater amounts of astigmatism can now be corrected with lenticular approaches. While the accuracy of these lenses are outstanding, identifying the access is particularly critical, as each degree of axis change results in 3% loss of effect. Thinking about it another way, if the lens is off axis by about 30 degrees (the distance between the 1 and 2 on a clock) there is almost no astigmatic correction whatsoever. In this regard, better ways of marking the axis (such as the Devgan toric marker) or better ways of confirming the axis intraoperatively (wavefront abberometry such as the Wavetec Orange) will be the next step in improving patient outcomes.
Presbyopic lenses: While toric lens volume grew substantially in the past year, presbyopic lens volume plateaued. While the overall number of lenses did not greatly increase, the choice of lens used was much different. For crystalens users, there was much more use of the new aspeheric AO model to the older HD model. Having an aspheric optic has allowed more refractive stability as well as less sensitivity to minor shifts in IOL position. Restor lens users gravitated to the +3 model over the +4, desiring greater intermediate vision for computer use. The next big change for restor users, however, is the upcoming restor toric IOL. Combining the multifocal platform on one side of the optic and the toric platform on the other, this should allow even better post-operative outcomes for patients not only with significant astigmatism but those with mild amounts as well. AMO/Abbott users continued to move from the Rezoom platform to the diffractive Tecnis multifocal. While overall use of presbyopic lenses did not greatly increase, this may be due to multiple factors, including dissatisfied patients with earlier models. As the newer technology lenses become implanted, we should expect a much greater uptake in 2012 if the results are indeed superior.
Overall, in spite of only one year passing, many things changed for cataract surgeons in 2011 regarding their IOL options. As we move into 2012, we should see even more shifts as even newer technologies such as light adjustable lenses (Calhoun) and accommodative IOLs (Tetraflex) become available.