A recently released study comparing the rotational stability of the two most widely used toric intraocular lenses—the AcrySof (Alcon) and the Tecnis (Johnson & Johnson Vision)—found that the AcrySof lens had significantly better rotational stability than the Tecnis.1 The retrospective study reviewed 1,273 eyes treated by two surgeons from the same practice, using the same techniques and equipment; 626 eyes received an AcrySof, while 647 received a Tecnis.
Findings of the study included:
• The AcrySof group showed significantly better rotational stability. The mean absolute value of rotation was 2.72 degrees (95% CI, 2.35 to 3.08 degrees) for AcrySof and 3.79 degrees (95% CI, 3.36 to 4.22 degrees) for Tecnis (p<0.05) at the first postoperative check. At the conclusion of surgery 91.9 percent of AcrySof eyes were aligned within 5 degrees of the axis, compared with 81.8 percent of Tecnis eyes (p<0.0001).
• The AcrySof group had significantly more lenses rotate ≤10 degrees and 15 degrees from the target axis (97.8 vs. 93.2 percent, p=0.0002, and 98.6 vs. 96.4 percent, p=0.02, respectively).
• The Tecnis tended to rotate in a counterclockwise direction (mean: 2.15 degrees). The AcrySof didn’t show the same tendency (mean: 0.38 degrees CCW, 95% CI, 0.04 degrees CW to 0.80 degrees CCW, p<0.05).
• Despite these differences, the refractive outcomes were statistically equivalent between groups. The mean postop cylinder was 0.30 D for the AcrySof and 0.31 D for the Tecnis (p=0.85). Other postop cylinder and acuity measurements were also similar.
• Further analysis showed that only lower IOL spherical equivalent power was associated with IOL rotation greater than 5 degrees (p=0.011). Both greater axial length (p=0.023) and toric axis (p=0.005 for with-the-rule target axis) were associated with IOL rotation greater than 10 degrees.
• Use of a capsular tension ring didn’t show any statistical benefit in preventing rotation greater than 10 degrees for either lens.
Bryan S. Lee, MD, JD, in private practice at Altos Eye Physicians in Los Altos, California, and an adjunct clinical assistant professor of ophthalmology at Stanford University, is lead author of the study. (He has no financial interest in the devices.)
Dr. Lee says several factors make the study valuable. “First of all, we studied almost 1,300 eyes,” he says. “They were consecutive patients from one practice, treated by two surgeons using the same technology and technique. Previous studies of rotation have had much smaller numbers of subjects, and variability in the techniques and technologies that were used.”
Another significant difference between this study and previous analyses was the way rotation was measured. “The initial time point used to gauge the stability of the IOLs in the FDA studies was not at the end of surgery, which is clinically the most important time,” he explains. “Instead, they used measurements taken later, such as at the slit lamp a day after surgery, and then compared that to the six-to-12-month endpoint. That’s a potential problem, because we now know that almost all toric IOL rotation happens in the first hour after surgery. This was documented in a study by Yasushi
Inoue, MD.2 We designed our study to look at the stability of the IOL from the conclusion of surgery.”
As noted, the overall visual outcomes were similar in both groups despite the rotational stability difference. Dr. Lee doesn’t think that takes away from the significance of the study, for several reasons. “Number one, in our study about half the patients in both groups had the lowest-power toricity,” he points out. “When a very low-toricity IOL rotates off-axis, the rotation may not be as symptomatic in terms of the refractive outcome and cylinder. Second, when we’re looking at improving our outcomes, as surgeons we have to focus on the things we can control. One of those is picking the technology we use, and these degrees of rotation eventually add up. Finally, these patients are paying extra for a premium IOL, and a greater degree of error may ultimately lead to more unhappy patients.”
Asked about possible explanations for the difference in rotational stability, Dr. Lee says it’s a difficult question to answer. “The lenses are quite different from each other,” he points out. “The AcrySof lens acrylic is much softer and the haptic has a bulb at the end of it. It’s also possible that the angle of the haptic is relevant. Unfortunately, we can only speculate. Ultimately, Johnson & Johnson will hopefully be able to figure that out.”
Asked to comment on the study’s results, Jonathan Talamo, MD, chief medical officer at J & J Vision, said the company couldn’t speculate on causes of rotation. “We do know that the Tecnis and AcrySof IOL platforms have several key differences in the way they’re designed and how they best function,” he says. “What’s worth noting is that the study found that a small amount of difference in toric IOL rotation alone was not a good predictor of refractive outcomes. In fact, both the Tecnis and AcrySof toric IOL treatment groups had 85 percent of patients within 0.5 D of [target] cylinder after surgery.”
There’s also speculation about other lenses that use these toric platforms. “Our study didn’t compare the toric Symfony and the toric ReSTOR,” Dr. Lee notes. “I’d say that in our practice—anecdotally—the toric Symfony has a tendency to rotate just like the Tecnis toric monofocal does. That’s what you would expect, because it’s the same platform, the same material and the same lens design. Our study doesn’t prove that the toric Symfony is going to rotate more than the toric ReSTOR, but I think that would be a reasonable thing to be concerned about.”
Dr. Lee hopes the results of the study will result in improvements in the Tecnis. “Overall, I still think it’s a great platform,” he says. “I think this discovery will ultimately be a good thing, not just for toric IOLs, but for future presbyopia-correcting lenses that may have an orientation requirement in order for them to work their best. I hope this will ultimately help get the best outcomes for patients and be beneficial for the profession.”
1. Lee BS, Chang DF. Comparison of the rotational stability of two toric intraocular lenses in 1273 consecutive eyes. Ophthalmology 2018 Mar 12. [Epub ahead of print]
2. Inoue Y, Takehara H, Oshika T. Axis misalignment of toric intraocular lens: Placement error and postoperative rotation. Ophthalmology 2017;124:1424-1425.
Omega-3s Questionable For Dry Eye
In early May, researchers from the Dry Eye Assessment and Management Study Research Group published a study that showed no significant differences between omega-3 fatty acids and placebo in relieving dry-eye symptoms.1
In this multicenter, double-blind trial, researchers randomly assigned patients with moderate-to-severe dry eye to receive either a daily dose of
3,000 mg of omega-3 supplements (n=349) or an olive oil placebo (n=186).
The primary outcome of the study was the mean change from baseline in the score on the Ocular Surface Disease Index, based on the mean scores obtained at six and 12 months.
The mean change in the OSDI score wasn’t significantly different between the supplement and the placebo groups (-13.9 points and -12.5 points, respectively). There were also no significant differences in the conjuctival and corneal staining scores, tear breakup time or Schirmer’s results. In addition, the rates of adverse events were similar. The researchers concluded that there were no significantly better outcomes between the groups.
Richard Davidson, MD, from the University of Colorado School of Medicine, weighs in on the results: “It’s a little bit confusing. If you really look at the study in detail, both the placebo and the omega group did show improvement, but there was no statistical difference between the two. So one could make the argument that in some patients, the omega supplement does help. According to the study and my experience, the omega supplement helps more with the symptoms of dry eye rather than the dry eye itself.
“However, I’m not surprised by the study,” Dr. Davidson continues. “I’ve never really been a huge omega-3 advocate because I didn’t really see that much of a difference in my practice. However, I have patients I’ve been seeing for 15 years who swear by them. In their opinion, they feel like it helps them—when they miss a few days, they feel worse. Are they getting the placebo effect? It’s quite possible, but you don’t always want to take that away from them. If my patients want to stay on them that’s fine, but I’m not going to advocate them routinely.”
Despite the somewhat unexpected results, Dr. Davidson is excited about them. “I love the study,” he says. “It was really well done, and I’m glad we have it because it justifies my own clinical observations. But at the same time, if you look closely at it, you could argue that people showed improvement even though there was no difference between placebo and omega-3s. The blood levels of the omega-3 group did go up, meaning it did get into the blood. However, in the placebo group there was no change in blood levels, which supports even more that there was no difference between the groups. We don’t yet have an explanation as to why the placebo group had improved symptoms so, hopefully, we’ll see some further studies exploring this.”
Dr. Davidson says the study may affect some practices. “For me, in my practice, this won’t really change anything,” he says. “It may change something for people who are heavy prescribers of omega-3 supplements, though. They’ll have to switch to something that has shown efficacy. At the same time they might argue, however, ‘Yes, I see what the study says, but I have patients who say that it helps them, so I’m going to stick with it,’ which I totally understand.” REVIEW
1.https://www.nejm.org/doi/full/10.1056/NEJMoa1709691 Accessed 07 May 2018.