Keys to managing astigmatism with toric IOLs
Toric IOLs plus laser arcuate incisions provide surgeons with the flexibility they need to perfect outcomes.
According to the 2017 ASCRS Clinical Survey, about 17% of respondents do not currently implant toric IOLs at all. And among those who do, only about 10% of their total cataract procedures involve a toric IOL. Cost is by far the most common reason given for not implanting toric IOLs, but lack of access to toric IOLs, the additional time required and difficulty in managing postoperative residual error are also among surgeons’ concerns.
To me, toric IOLs and limbal relaxing incisions represent a huge opportunity to grow the refractive cataract surgery practice. Correcting even low levels of astigmatism can improve image quality and greatly increase patients’ satisfaction with their postoperative vision. If you are using cylinder correction in your spectacle prescriptions and you perform cataract surgery, you should strongly consider using toric IOLs, if you are not already doing so.
In my practice, patients have a choice of “good,” “better” or “best” cataract surgery. The “good” category is manual cataract surgery with a standard IOL that is covered by insurance or Medicare. Patients should expect to wear glasses at all distances after surgery. The “better” package includes one upgrade (either femtosecond laser or a premium lens), as well as the ORA intraoperative aberrometry system (Alcon). The “best” package includes both the laser and a toric or presbyopia-correcting IOL, along with intraoperative aberrometry, with the goal of good uncorrected vision at most distances when using a presbyopia-correcting IOL. Any patient who chooses a femtosecond laser-assisted cataract surgery (FLACS) package also gets excimer laser vision correction touchups, if needed.
Approach to astigmatism correction
Preoperatively, I obtain at least two sets of topography measurements and two Lenstar (Haag-Streit) biometry measurements to verify the amount and axis of astigmatism. I like all four to match as closely as possible, and I pick the average axis based on these measurements.
The amount of astigmatism I aim to correct varies according to the axis. If the patient has against-the-rule astigmatism, I treat all of it and may even aim to flip the axis. In eyes that have with-the-rule astigmatism, I treat less aggressively, aiming to leave the patient with 0.25 D to 0.5 D of with-the-rule astigmatism.
For low amounts of astigmatism, I perform manual limbal relaxing incisions or laser arcuate incisions (Figure 1). However, my preference in most cases with even moderate astigmatism is to combine femto arcuate incisions with a toric IOL. (Click here to watch video.) Placing a small pair of anterior penetrating laser arcuate incisions provides me with the greatest flexibility for fine-tuning the correction. I do not open the incisions at the time of surgery, but having them there provides the option to open the incisions, manually extend them and/or perform laser vision correction as required to augment the effects of the toric IOL. The laser arcuate incisions also serve as useful marks for toric lens placement.
For the lens implant, I prefer the Tecnis family of toric IOLs (Johnson & Johnson Vision). The clear optic and the correction of spherical and chromatic aberration provide patients with excellent postoperative quality of vision.
I use ORA intraoperative aberrometry to confirm or adjust both the sphere and cylinder power intraoperatively. To get the most out of this technology, I think it is important to check IOP with a tonometer before making my primary cataract incision (Figure 2). That means that I make the primary and paracentesis wounds manually in the operating room, rather than with the laser. My goal is to match the aphakic IOP to my pre-incision IOP when I have completed phacoemulsification and am ready to use ORA to choose the final lens power. (Click here to watch video.)
After implanting the IOL, I use ORA to check the lens position. Rather than wasting time with multiple captures, I simply watch the device’s live stream for rotation advice, adjusting the IOL position until I am confident of a “no rotation recommended.” One also must be cognizant of factors that could affect the accuracy of the ORA reading, including wound edema from leakage or stromal overhydration, vitreous opacities or corneal disruptions.
If I have any concerns about maintaining the IOL position in the setting of a large capsule or zonular instability, I implant a capsular tension ring to lock the lens in place.
No matter how well we prepare, there is always a level of uncertainty about how the patient will heal, which is why it is useful to have a FLACS/laser vision correction package that allows for postoperative fine-tuning. For cases with poor results, www.astigmatismfix.com is an excellent resource. However, with the approach described here, I find repositioning of toric IOLs to be exceedingly rare.
- For more information:
- Eva Liang, MD, can be reached at Center for Sight, Las Vegas; email: email@example.com.
Disclosure: Liang reports she is a consultant to Johnson & Johnson Vision and Bausch + Lomb.