It's been a little over a year since Bausch & Lomb's Crystalens HD was approved in the
The Crystalens HD relies on pseudo-accommodative movement of the lens optic, and a small increase in near power located in the center of the lens, for its refractive effects.
Surgeons say it's important to take these attributes into account when trying to make patients happy with the lens.
The Need for Enhancement
Of course, surgeons say that no matter how exacting you are with your preop biometric measurements, there will be a certain percentage of Crystalens HD patients who don't hit their targets.
"I think that, with an accommodating lens like this, you have to be a refractive surgeon and expect an enhancement rate somewhere between 10 and 15 percent," says Dr. Whitman. "If you can't handle that, you really shouldn't get involved with this lens. This also means you have to perform limbal relaxing incisions to get the cylinder below 0.75 D. Even though these lenses have been approved for the correction of cataract with up to
1 D of cylinder, most experienced refractive surgeons will tell you that patients won't accept 0.75 D of astigmatism. It's not good enough.
"Most of the patients I have to enhance are being enhanced for anatomic reasons," Dr. Whitman continues. "The accommodative lenses are subject to the size, diameter and depth of the capsular bag—they conform to it. This is in contrast to other lenses that push out to the equator of the bag and make it stiff, allowing you to predict where the effective lens position's going to be, pretty much every time. If it's a deep capsular bag or a narrower-diameter bag, that will make the HD sit differently than a larger, deeper one.
As a result, some surgeons are reporting that the patient looks great at day one, and then, at one to three weeks postop, the lens seems to be sitting planar, not posteriorly as they'd like it to. So, there's a subset of patients, about 10 to 15 percent in my experience, in whom it will sit a little more anterior, which will make them a little more nearsighted."
He says this can be a bigger issue with the Crystalens HD than it was with the previous model because the HD is made with an increased depth of focus in the center of the lens that causes it to produce more minus for the patient to begin with.
Patients need to be prepared for the possibility of an enhancement, as well. "It's important to discuss what happens if there's residual refractive error," says
"On the astigmatism side, while we can do a pretty good job with corneal and limbal relaxing incisions, we can sometimes have residual astigmatic error," says Dr. Lindstrom.
"We have to fix that. If the patient has a healthy ocular surface I'll do IntraLase LASIK.
But, a lot of these patients are seniors and may not have a perfect ocular surface. In such cases, surface ablation works great. Also, I perform a conventional or wavefront-optimized ablation, not a custom one. Because of the nature of the Crystalens HD optic, we don't want to counteract the depth of focus that's improved by the optic by negating it with a custom wavefront-driven enhancement."
Part of helping avoid a postop "surprise" also involves the way you close the case, surgeons say. "You want to ensure good centration of the lens and that it's vaulted posteriorly," explains
Another tip some surgeons offer is to properly time your YAG capsulotomy. "I, personally, like to do any YAG laser capsulotomy before the laser enhancement," says Dr. Lindstrom. "This is because, in some cases, the lens shifts a bit when you do the YAG. I've had a few patients, especially if they ended up a little on the myopic side, that actually had good outcomes after I did the YAG, and didn't need a laser enhancement. In addition, if you do the laser enhancement first and then later open the capsule, sometimes the lens shifts a bit again. So, almost all of my premium IOL patients, whether Crystalens or multifocal, almost always end up with a YAG laser capsulotomy, because I'm pushing for that last bit of quality of vision with these premium lenses."
One novel technique that Dr. Lindstrom uses to help ensure a good result in his Crystalens patients involves using a longer course of steroids. "For an accommodating lens, capsular fibrosis is the enemy," he says. "So, I continue the steroid course a little longer. I instill a drop of steroid preop when administering the antibiotic and non-steroidal. And, postoperatively, I give an antibiotic q.i.d. for two weeks and prescribe the steroid q.i.d. for two weeks, then cut it down to b.i.d. for two months. Continuing the topical steroids can be helpful as a way to retard capsular fibrosis and retain capsular elasticity in these patients. It's also beneficial for the ocular surface, helping to create a surface that's as healthy as possible. Also, we don't want even minimal, subclinical cystoid macular edema in these patients, who are trying for the best quality uncorrected vision they can get."