IOL exchange all about setting patient expectations, determining plan of action
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With modern calculations and state-of-the-art lenses, IOL exchange is not regularly needed.
According to Healio/OSN Section Editor Uday Devgan, MD, it is downright rare, at least in his practice.
Source: Jennie L. Scott Photography
“For at least 99% or more of patients who have had surgery to implant an IOL, you never explant the lens,” he said. “That’s the lens they get for the rest of their lives.”
If he is going back into the eye to explant and replace a lens, he makes sure the patient knows what to expect.
“No manmade lens is going to give you perfect vision,” Devgan said. “You aren’t taking their vision back to what it was when they were 30 years old. You’ll make it better, but to a degree, they should expect to be a little less than perfect.”
However, for that 1% of patients, an IOL exchange may be the best option. Knowing which patients are the best candidates, as well as knowing what to look for preoperatively and intraoperatively, can be crucial for producing the best visual outcomes.
The simplest and most common reason for patients to seek an IOL exchange is that they are not happy with their initial results, according to OSN Technology Board Member Kathryn M. Hatch, MD.
“Especially in routine surgery, it’s when certain expectations weren’t met,” she said. “That could mean the patient had a refractive surprise or they didn’t end up with their intended goals.”
Another reason why patients may need an exchange is dysphotopsias that cannot be tolerated.
“Patients can rarely experience issues, even years after cataract surgery, that would necessitate an exchange,” Hatch said. “There can be mechanical issues where the lens dislocates, possibly related to zonulopathy or trauma.”
In patients who have a refractive miss, J. Morgan Micheletti, MD, will consider an exchange when they are not good candidates for an enhancement with LASIK or PRK. If he is working with a patient who recently underwent cataract surgery, he does not rush to do an exchange in order to allow the refraction to stabilize.
“I like to push them out at least far enough where we can make a good assessment,” he said. “When both eyes are done, we can decide whether we want to do LASIK or if we need to address it with an exchange. That’s assuming we’re working with a refractive miss. If they are getting glare or halos with their first eye from a multifocal or EDOF IOL, sometimes we will change the lens on the second eye and determine if we need to go back for an exchange on the first lens.”
The process for an exchange after implantation of a multifocal or extended depth of focus IOL typically takes place 3 to 6 months after the initial surgery to allow time for the patient to potentially neuroadapt.
“When deciding on an exchange due to visual disturbances, it’s really a balance between neuroadaptation, stable refraction and managing the patient’s symptoms,” Micheletti said.
Considerations
There are important considerations before performing an IOL explantation and exchange, many related to the state of the eye and how many times it has undergone surgery.
“It’s always best to operate on an eye that’s never had prior surgery, but when doing an IOL exchange, you’re on at least surgery number two,” Devgan said. “They may have had other surgeons in the eye. The risk is that for each subsequent surgery, it becomes more challenging than the previous one because there is more scar tissue. Then, there can be issues with the endothelial cell count. Is there enough, or is this lens exchange going to push the patient over the edge to corneal failure?”
The time between surgeries is a concern, too, according to Hatch.
“The further out the exchange is from the original surgery, the more possible fibrosis and scarring there can be,” she said. “If we’re going to exchange a lens, ideally we would want to do it in the first few months after the procedure. We can definitely explant lenses even years later, but when you do something later on, there is going to be additional challenges.”
The most important factor may be the state of the posterior capsule. The integrity of the capsular bag will likely determine the technique used to explant the lens, as well as the new type of implant. Additionally, if the capsular bag is intact, it is important to protect it moving forward through the explantation process.
“If you’re dealing with an open capsule vs. a closed system, it can make the procedure a bit more difficult,” Hatch said. “An open capsule can obviously present some potential risks, such as vitreous loss and other challenges.”
This is a concern in patients who have previously undergone YAG laser capsulotomy, according to Devgan.
“You may end up causing vitreous prolapse,” he said. “Removing the lens from the eye is not as simple, and it can become fibrosed or stuck in place. Sometimes, it can be very hard to dissect that lens out.”
No matter the initial state of the eye or capsule, Micheletti said the surgeon should take their time.
“Take your time and don’t rush,” he said. “Make sure the haptics are completely free from the capsule at all planes using OVD or a bimanual approach. Once you get the lens up, protect the endothelium and the capsular bag.”
Some patients may not be candidates for IOL exchange. Micheletti said that includes patients who are at higher risk for surgery in the first place, such as those with pseudoexfoliation or zonulopathy.
“These are the ones where you have to be very careful and really make sure that lens exchange is the right choice because you will only put more stress on the zonules as part of the exchange,” he said. “The other concern is in patients with shallow anterior chambers. Not to say that it can’t be done, but it’s a bit more challenging because you don’t have quite as much room to work with.”
Ashvin Agarwal, MD, has several steps to protect the eye in cases in which the capsular bag is intact.
“There may be cases where the bag could be stuck to each side of the haptic site,” he said. “I try to release those first by injecting some viscoelastic into the anterior and posterior chambers and use a simple rod to sweep in and out to ensure that it balloons and opens up nicely.”
Once the haptics are freed, Agarwal said the next step is to visualize them. The best way to do that is by using an iris hook.
“Don’t try to be a hero and not use the iris hooks because they really help us to visualize,” he said. “If I can see it, I can do it. It’s a simple philosophy.”
Hatch also advocated for iris hooks to aid in visualization, particularly in patients with more complicated histories.
“That’s when visualization can be challenging,” she said. “Especially for surgeons who are learning new techniques, it’s always important to make sure you can visualize what you’re doing. Use your iris hooks for visualization, and then move slowly and take your time when doing these intricate intraocular maneuvers.”
Techniques
There are several techniques surgeons can use to explant a lens. Hatch said most modern lenses are made of a soft material such as acrylic and can be easily manipulated or even cut inside the eye.
“If it’s an AcrySof (Alcon) lens, I’ll typically externalize one of the haptics and see if I can grab it,” she said. “Sometimes, it might need a small ‘Pac-Man’ cut through the central optic. From there, you’re usually able to sort of ‘taco’ it out of the incision, and that seems to work fairly well.”
For harder lenses, such as a PMMA lens, Agarwal said it may be necessary to open a scleral wound to explant it. However, for cases with an intact capsular bag, Agarwal will almost always choose to cut the IOL with microscissors.
“These days, all the lenses we use are acrylic, silicone or some kind of hydrophobic or hydrophilic material,” he said. “All of them are easily cut with the use of microscissors.”
However, this technique introduces two sharp objects into the eye. Part of the procedure is protecting the posterior capsule (below) and the cornea (above) from the scissors as the IOL is cut into pieces.
Agarwal said he protects the capsular bag by first inserting the new IOL into the eye.
“If the scissors touch the posterior capsule, that simple touch is enough for it to rupture,” he said. “However, having placed that new IOL inside, I am protecting my scissors from touching the bag.”
To protect the cornea, he liberally uses viscoelastic, causing the anterior chamber to swell and giving him more room to make his cuts without touching the endothelium.
The technique of placing the new IOL, known as IOL scaffolding, is gaining traction among surgeons. Hatch said she has used it and called it a good option, particularly in patients with deeper eyes.
“The new lens acts as a nice diaphragm and protects the bag,” she said. “It depends on the patient. If they have a smaller eye, it can make the space you’re working in a lot smaller, and the anterior chamber may be too shallow.”
Devgan and Micheletti are both advocates of the “twist and out” technique. The surgeon makes a small corneal incision — 2.2 mm or 2.4 mm compared with about 2.75 mm or larger — and separates the IOL from the capsular bag, bringing the lens up into the anterior chamber and taking one of its haptics through the incision. Devgan said it is important to insert a straight spatula through the paracentesis incision and place it above the lens in order to protect the cornea during the twist. This allows use of the technique even in shallower eyes.
From there, the surgeon uses straight forceps to grasp the IOL.
“You’re going to start with your hand as supinated as possible, and then you just rotate it all the way through,” Micheletti said. “You want to get that big rotation. By wrapping the lens around the forceps, you can pull it right out through the wound.”
The twist and out technique has several benefits. It explants the lens in one piece, and while little can be learned from a lens that has been cut, an intact lens can be studied for defects.
“It’s a great nontraumatic way to get the lens out in one piece,” Micheletti said. “Especially if there’s something off with the lens, you want to be able to send it back to the manufacturer so they can learn from whatever was different or unique about this lens.”
Another benefit is patient tolerability. Devgan said patients want an exchange because they can no longer tolerate their current lens and because they want a better visual outcome once the procedure is done.
“They want to see 20/20 once the new lens is in there,” he said. “If you make a big incision, cut the lens and pull on it without twisting at all, now you’re going to start seeing a lot of astigmatism.”
Cases in which the posterior capsule is still intact are the easy ones, according to Agarwal. Things start to get difficult when the capsular bag is no longer intact. He said in these cases, the vitreous can start mixing into the anterior chamber, and there is a risk that the IOL may dangle or drop down into the posterior chamber.
One method he uses for these cases is the three-port pars plana technique.
“The difference here is, you don’t pull the lens into the anterior chamber. First, do a total vitrectomy, releasing all the vitreous from the IOL,” he said. “Once you remove any vitreous or cortex, then you have a free and mobile IOL in the mid-vitreous, which you’re holding onto. Grabbing onto it using a bimanual technique, you can then bring it into the anterior chamber, just like the previous cases.”
Once the IOL is in the anterior chamber, it can be removed with the same methods as other lenses. In Agarwal’s case, that means a scleral tunnel technique or using microscissors.
However, he will first place the new IOL to prevent pieces of the original lens from dropping back into the posterior chamber.
“I will place an intrascleral haptic fixation of my future lens already inside the eye,” he said. “That will act as my scaffold to protect against half of the old IOL falling down.”
No matter how the original lens is removed, Agarwal said the most important part of the exchange process is getting that next IOL calculation correct.
“You want to double or triple check that calculation,” he said. “You want to be deadly sure you’re not going to have to repeat that once again. Get another person’s opinion, if need be, because you don’t want to be going back to that route.”
Devgan said it is critical that patients know that IOL exchange is a salvage surgery and that their vision will not be perfect afterward.
“Set expectations,” he said. “I say, ‘If you can live with your existing lens, then live with it. If you can’t, then OK, I’ll change it, and I’ll do my best to give you good vision.’ There are no manmade body parts that are as good as natural ones.”
Hatch said setting those expectations and educating patients are all part of the process.
“There is no IOL that is totally exempt from these potential small risks,” she said. “We have to do our best job from the beginning to determine what is the best lens for someone. That takes time and careful discussion with the patient.”
- Reference:
- Pandit RT, et al. J Cataract Refract Surg. 2020;doi:10.1097/j.jcrs.0000000000000161.
- For more information:
- Ashvin Agarwal, MD, can be reached at Dr. Agarwal’s Eye Hospital, #222, TT Krishnamachari Road, Alwarpet, Chennai, 600018, India; email: agarwal.ashvin@gmail.com.
- Uday Devgan, MD, can be reached at Devgan Eye, 11600 Wilshire Blvd. #200, Los Angeles, CA 90025; email: devgan@gmail.com.
- Kathryn M. Hatch, MD, can be reached at Mass Eye & Ear, 1601 Trapelo Road, Suite 184, Waltham, MA 02421; email: kathryn_hatch@meei.harvard.edu.
- J. Morgan Micheletti, MD, can be reached at Berkeley Eye Center, 1435 Highway 6, #202, Sugar Land, TX 77478; email: morgan.micheletti@berkeleyeye.com.
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