BLOG: Range of toric lens choices available for patients electing astigmatism management
Many surgeons have a refractive package for patients who are seeking spectacle independence at distance.
This typically includes more robust measurement and management of astigmatism, using a variety of technologies that might include advanced corneal diagnostics, femtosecond laser, toric IOLs and corneal relaxing incisions.
For years, many surgeons prioritized rotational stability above all else in selecting a toric IOL platform. Today, however, we have three toric IOL platforms with excellent rotational stability.
At the recent American Society of Cataract and Refractive Surgery meeting in Washington, Edward Hu, MD, PhD, retrospectively evaluated repositioning rates for 812 consecutive toric lens cases over about 4 years. He found that 2.5% of AcrySof toric IOLs (including monofocal, ReSTOR, PanOptix and Vivity models, all Alcon), 1.6% of Tecnis toric II lenses (including the monofocal, Eyhance and Synergy, all Johnson & Johnson Vision), 5.7% of the older Tecnis toric I platform and 1.1% of enVista torics (Bausch + Lomb) required repositioning at week 1.
Two other researchers who presented at ASCRS on nearly 500 eyes implanted with Tecnis toric II IOLs found mean postoperative rotations of 0.71° to 0.94°, with 99% to 100% of eyes rotating 5° or less. Clearly, these newer platforms are extremely stable.
That doesn’t mean one will never need to reposition; capsular bag dynamics can also affect the likelihood of rotation. When I see a patient in the early postoperative period who isn’t seeing as well as I would expect, I like to use the iTrace “toric check” feature (Tracey Technologies). My technician can run this check in 30 seconds, without the need for dilation. It compares the corneal astigmatism to the internal astigmatism power and axis of the lens and tells you exactly how many degrees off-axis it is and whether rotation would be beneficial (Figure 1).
Another factor I consider for my astigmatism management patients who need a toric IOL is the quality and range of vision the lens can provide. These refractive patients, who haven’t chosen presbyopia correction but do want to be able to see without glasses at distance, are great candidates for an enhanced monofocal. The relatively small additional cost of the lens can easily be wrapped into the refractive package.
Another paper at ASCRS that was of particular interest to me was a prospective study by Oliver Findl, MD, MBA, FEBO, and colleagues on visual outcomes with the enhanced monofocal Tecnis Eyhance toric in 50 eyes. They found very low mean absolute rotation (1.47°) at 1 hour (the time when rotation is most likely to occur). Distance vision was excellent, as we would expect with any correctly positioned toric monofocal, but the slightly increased depth of focus with this lens meant that 70% of the eyes in the study had uncorrected intermediate (66 cm/26 in) vision of 0.1 logMAR (20/25) or better. That’s a very nice additional benefit for patients who have opted for a refractive cataract surgery procedure.
Finally, it is also important to tread carefully with toric IOL selection if there is any history of refractive surgery. In a post-myopic LASIK patient with regular astigmatism, Eyhance toric is a great choice because it may offset the positive spherical aberration (SA) of the post-myopic LASIK cornea, while also providing a slightly broader landing zone for these more challenging eyes.
In a post-hyperopic LASIK eye with astigmatism, I prefer to use the SA-free enVista toric IOL. This may also be a good choice for eyes that are on the borderline between needing a toric lens vs. just relaxing incisions. The enVista lens comes in the lowest toric power available in the U.S., correcting 1.25 D at the IOL plane or 0.9 D at the corneal plane compared with 1.50 D at the IOL plane or 1.03 D at the corneal plane for the Tecnis and AcrySof platforms. It’s also important to get multiple keratometry measurements in post-hyperopic eyes. I have found that relying on just a biometer or anterior simulated keratometry alone can result in significant overcorrection of astigmatism. Fortunately, I have access to the Cassini Ambient (Cassini Technologies), which measures posterior astigmatism and gives a true total corneal astigmatism measurement.
We are fortunate to have such good options for astigmatism management. In selecting an IOL platform, it is important to consider not only rotational stability, but the quality and range of vision and the patient’s refractive history.
References:
Chang DH. Rotational stability and surgeon satisfaction of a toric intraocular lens with modified haptics: 3-month clinical results. Presented at: American Society of Cataract and Refractive Surgery meeting; April 22-26, 2022; Washington.
Findl O, et al. Rotational stability of a toric monofocal intraocular lens with an extended depth of focus. Presented at: American Society of Cataract and Refractive Surgery meeting; April 22-26, 2022; Washington.
Hu E. Incidence of clinically significant rotations in toric IOL platforms: A retrospective consecutive case series. Presented at: American Society of Cataract and Refractive Surgery meeting; April 22-26, 2022; Washington.
Quesada G. Subjective and objective assessments of performance of a toric intraocular lens with modified haptics. Presented at: American Society of Cataract and Refractive Surgery meeting; April 22-26, 2022; Washington.
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