New toric lens demonstrates rotational stability
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I am a firm believer in correcting astigmatism at the time of cataract surgery. Nearly 40% of patients undergoing cataract surgery in the U.S. have significant astigmatism, greater than 1 D, and the prevalence increases with age.
Although many surgeons focus on presbyopia-correcting IOLs, there is also significant value to simply correcting astigmatism. It can mean that patients pay much less for their glasses after surgery and are not dependent on astigmatic spectacles, which may be a contributor to fall risk. Even correcting lower amounts of astigmatism with incisions has been shown to improve visual performance. Unfortunately, no astigmatism correction is attempted in about half of all cataract cases.
Toric IOLs
I recommend toric IOLs for any patient with corneal astigmatism greater than 0.75 D against-the-rule or 1 D with-the-rule and incisional correction with anterior penetrating femtosecond laser arcs for lower amounts of astigmatism. Until recently, however, I was not fully satisfied with any of the toric lenses on the market. I preferred the optical quality of the Tecnis platform but did not like that the toric lenses sometimes rotated.
I recently began using the ZCU toric IOL (Tecnis toric II, Johnson & Johnson Vision). This new toric lens platform has the same optical quality of its predecessor, but a change in the haptic polishing technique provides more resistance to rotation. While not difficult to position correctly, the newer style haptics make it appreciably more stable.
At the 2020 American Academy of Ophthalmology meeting, two studies were presented that confirm my personal impressions of the performance of this IOL.
In one of these, eight surgeons were asked to rate their subjective satisfaction with the lens 3 months after implanting their first 10 lenses or so. Nearly all (96.6%) of the surgeons reported being extremely or quite a bit confident in their ability to control the lens position, and 100% were satisfied to very satisfied with the overall clinical outcomes, rotational stability and uncorrected vision at 3 months.
In the other study, 200 eyes were implanted with the ZCU IOL at six clinical sites. Image analysis software was used to measure any change in lens position postoperatively. One week after surgery, the mean absolute rotation was 0.77° ± 0.65°, and all eyes had 2° of axis misalignment or less. Patients achieved excellent postoperative visual acuity results, with a mean residual refractive cylinder of just 0.23 D.
Perfect for a long eye
I recently implanted the ZCU in the left eye of a 62-year-old female patient with a history of retinal detachment in both eyes, which had been repaired with pars plana vitrectomy and scleral buckle several years prior. She was a high myope (–6.75 –2.25 × 162 in the left eye) with an axial length of 26.55 mm. Long eyes are associated with larger capsular bags and a higher risk of postoperative IOL rotation. Pentacam imaging (Oculus) revealed 2.5 D of regular with-the-rule astigmatism (Figure 1).
Source: Douglas K. Grayson, MD
The patient was interested in spectacle independence. However, due to the history of retinal detachment, she was not a good candidate for a presbyopia-correcting IOL. Given the significant corneal astigmatism, I explained that a toric IOL would help her achieve the best possible visual acuity at distance.
Cataract extraction was performed with my preferred phaco tilt technique and a Grayson nucleus manipulator (Storz/Bausch + Lomb) as the second instrument. I implanted a +12.00 D ZCU375 Tecnis toric II, with an axis of 75° and predicted residual cylinder of –0.34 D (Figure 2). I also created 15° anterior penetrating incisions at 75°. These serve as a marker for placement of the toric IOL but also provide an additional 0.25 D of astigmatic correction.
I used the arcuate incisions and a Mendez toric marker to confirm placement of the IOL in the correct axis (Figure 3). On postop day 1, the patient’s visual acuity in the operated eye was 20/30, with mild corneal edema. By 3 weeks postop, vision had improved to 20/20, the lens was well aligned, and the patient was happy with the outcome (Figure 4).
Ongoing improvements in toric lens technology are important for our patients. Many of them do not qualify for presbyopia correction but want to reduce dependence on glasses as much as possible. By focusing on perfecting astigmatism management, we can offer these patients great uncorrected distance vision for the rest of their lives, so that they only need to wear glasses for near tasks.
- References:
- Anderson DF, et al. Clin Ophthalmol. 2018;doi:10.2147/OPTH.S146829.
- Hill WE. Prevalence of corneal astigmatism prior to cataract surgery. www.doctor-hill.com/iol-main/astigmatism_chart.htm. Accessed Dec. 17, 2019.
- Kim H, et al. Value Health. 2010;doi:10.1016/S1098-3015(11)73365-4.
- Lehmann RP, et al. Clin Ophthalmol. 2012;doi:10.2147/OPTH.S28241.
- Lord SR, et al. J Am Geriatr Soc. 2002;doi:10.1046/j.1532-5415.2002.50502.x.
- Market Scope. 2019 annual sponsored US cataract surgeon survey report. May 2019.
- Waring GO, et al. Subjective and objective assessments of a toric intraocular lens with modified haptics. Presented at: American Academy of Ophthalmology annual meeting; Nov. 13-15, 2020 (virtual meeting).
- For more information:
- Douglas K. Grayson, MD, can be reached at Omni Eye Services of New Jersey and New York; email: dkgrayson@me.com.
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