Range of toric lens choices available for patients choosing astigmatism management

Many surgeons have a refractive package for patients who seek the independence of distance glasses.

This typically includes more robust measurement and management of astigmatism, using a variety of technologies which may include advanced corneal diagnostics, femtosecond laser, toric IOLs, and corneal relaxant incisions.

Jared Young

For years, many surgeons have prioritized rotational stability above all else when selecting a toric IOL platform. Today, however, we have three toroidal IOL platforms with excellent rotational stability.

At the recent meeting of the American Society of Cataract and Refractive Surgery in Washington, Edward Hu, MD, PhD, retrospectively evaluated repositioning rates for 812 consecutive toric lens cases over approximately 4 years. It found that 2.5% of AcrySof toric IOLs (including monofocals, ReSTOR, PanOptix and Vivity, all Alcon), 1.6% of Tecnis toric II lenses (including monofocals, Eyhance and Synergy, all Johnson & Johnson Vision), 5.7% of the old Tecnis toric I platform and 1.1% of the enVista torics (Bausch + Lomb) required repositioning at week 1.

Two other researchers who presented nearly 500 eyes implanted with Tecnis toric II IOLs to ASCRS found average postoperative rotations of 0.71° to 0.94°, with 99% to 100% of eyes rotating 5° or less. Obviously, these new platforms are extremely stable.

This does not mean that we will never need to reposition ourselves; the dynamics of the capsular bag can also affect the probability of rotation. When I see a patient in the early postoperative period who is not seeing as well as I expected, I like to use the “toric check” feature of iTrace (Tracey Technologies). My technician can perform this check in 30 seconds, without the need for dilation. It compares corneal astigmatism to internal astigmatism power and lens axis and tells you exactly how many degrees it is and if rotation would be beneficial (Figure 1).

Figure 1. An iTrace review recommends a rotation to the 1 week exam after placement of a toric IOL.

Source: Jared Younger, MD

Another factor I consider for my astigmatic patients who need a toric IOL is the quality and range of vision the lens can provide. These refractive patients, who have not chosen the correction of presbyopia but wish to be able to see without glasses at a distance, are excellent candidates for a reinforced monofocal. The relatively low additional cost of the lens can easily be integrated into the refractive housing.

Another ASCRS paper that was of particular interest to me was a prospective study by Oliver Findl, MD, MBA, FEBO and colleagues of visual outcomes with the Tecnis Eyhance enhanced monofocal toric in 50 eyes. They found a very low mean absolute rotation (1.47°) at 1 o’clock (the time when rotation is most likely to occur). Distance vision was excellent, as you would expect with any properly positioned toric monofocal, but the slightly increased depth of field with this lens meant that 70% of eyes in the study had uncorrected intermediate vision (66 cm/26 in) of 0.1 logMAR (20/25) or better. This is a very attractive additional benefit for patients who have opted for refractive cataract surgery.

Finally, it is also important to exercise caution when selecting toric IOLs if there is a history of refractive surgery. In a post-myopic LASIK patient with regular astigmatism, Eyhance toric is an excellent choice because it can compensate for the positive spherical aberration (SA) of the post-myopic LASIK cornea, while providing a slightly wider landing zone for those tougher eyes.

In a post-hyperopic LASIK eye with astigmatism, I prefer to use the enVista toric IOL without SA. It can also be a good choice for eyes that are on the borderline between needing a toric lens and simple relaxing incisions. The enVista lens is available in the lowest toric power available in the United States, correcting 1.25 D at the IOL plane or 0.9 D at the corneal plane compared to 1.50 D at the IOL plane or 1.03 D at the corneal plane for Tecnis and AcrySof platforms. It is also important to obtain multiple keratometry measurements in post-hyperopic eyes. I have found that relying solely on a biometer or simulated anterior keratometry can lead to significant overcorrection of astigmatism. Fortunately, I have access to the Cassini Ambient (Cassini Technologies), which measures posterior astigmatism and gives a true measurement of total corneal astigmatism.

We are fortunate to have such great options for managing astigmatism. When selecting an IOL platform, it is important to consider not only rotational stability, but also the quality and extent of vision and the patient’s refractive history.

References:

Chang DH. Rotational stability and surgeon satisfaction of a toric intraocular lens with modified haptics: clinical results at 3 months. 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 extended depth of field. 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 performance evaluations of a toric intraocular lens with modified haptics. Presented at: American Society of Cataract and Refractive Surgery meeting; April 22-26, 2022; Washington.