With so many variables in today’s cataract surgeries, thorough preoperative testing and expectation-setting are crucial to patient satisfaction. We spoke with Cathleen McCabe, MD, about her best practices in this area.
Ophthalmology Management: What are some key strategies and considerations for optimizing IOL outcomes?
Cathleen McCabe, MD: As my career has progressed, we have gone from a “disease state” approach to cataract surgery to using it as a vehicle for improving our patients’ quality of life. Yes, it’s an opportunity to get rid of a cataract, but it’s also an opportunity to create better visual health—and that’s a completely different mindset. Today, I really think about the outcome of that cataract surgery on the patient’s ability to do things they want to do with ease.
To focus on that outcome, I have to think preoperatively, intraoperatively, and postoperatively about the steps that are necessary to achieve it: What are the patient’s needs? What are the patient’s goals? For example, they might want to be free from wearing glasses for distance but don’t mind wearing readers. Or they might want to have maximal independence from glasses because they’re highly active outdoors, or because they [have trouble] remembering where they put their readers. It’s not just people who are “living their best lives,” but patients who are struggling with other disabilities and don’t want vision to be yet another obstacle for them in performing their daily activities.
I want to understand the patient and their whole health. Are they in an environment where dry eye is a bigger issue? Do they have a family history of progressive eye disease, such as macular degeneration or glaucoma, that would impact future performance of the lenses we choose today? I’ll look for early signs of progressive disease with more detail than I might have in the past.
OM: What types of preoperative testing do you do routinely? What do you look for?
CM: I get a preoperative optical coherence tomography (OCT) of the macula and the optic nerve on every patient, because there are things we can’t see in the macula even in the best of circumstances. Typically, that view into the back of the eye is compromised by the cataract as well.
I’m looking for early signs of macular degeneration: maybe some fine drusen or fine retinal pigment; epithelial changes; vitreomacular traction; or little cysts in the fovea. [Any of these] might change a decision I would make about technology to help the patient see better. I think about the patient not just at their one-day post-op or their one-month post-op—when I want them to be absolutely thrilled with us for achieving their goal—but to continue to have the best outcome for the entirety of their life.
Doing that takes a little bit more digging than we’ve done in the past. Sometimes, the results of the OCT will lead me to do other testing. I’ve had patients with a lot of thinning of the RNFL that I may not have noticed because the cup-to-disc ratio was normal in both eyes, and symmetric. This might lead me to further investigate [to the point] where I really understand that this patient has other pathology. In those instances when I do see early signs of progressive diseases, I then think about the compromises I might make when choosing intraocular technology for the patient.
OM: How have test results changed your lens technology choices for patients?
CM: One of our best tools for giving patients a full range of vision with cataract surgery is a multifocal diffractive optic. It provides focus over a wide range of distances, from far to intermediate to near, often with trifocality within the optic. There are many different optical designs today, which is great for a healthy eye because it can provide the patient with independence from their glasses.
However, if there is macular pathology or evidence that there might be future macular or optic nerve pathology, then I don’t want to compromise contrast sensitivity and the amount of light being used. Part of the compromise we make with diffractive optics is the splitting of light and decrease in contrast sensitivity.
Another disease I carefully look for in the macula is an early epiretinal membrane. Because we now do these tests so early, we see those much sooner than in the past. The challenge has been to understand when this is a risk of something that could have meaningful effects on the visual system, and when it is just an incidental finding. As we do these tests and follow these patients longer, we’re getting better [at finding] where our comfort level is in making those choices.
I will also carefully examine the cornea in the pre-op period because I want to understand whether there is astigmatism. Usually, there is some, but how much? In what direction is it? Is it with the rule or against the rule? Are all the layers of the cornea healthy?
I also want to know if the patient has early signs of anterior basement membrane dystrophy or Fuchs endothelial dystrophy, because these might impact the quality of vision we can achieve with certain [IOL] technologies. Then I want to know the shape of the cornea or if the patient had previous corneal refractive surgery. We have so many different choices today, and patients aren’t always good at telling us that they’ve had procedures done before. A very in-depth look at topography and tomography is important in these patients so we can assess the cornea and the amount, magnitude, and direction of astigmatism.
Some things we were concerned with in the early days of multifocal lenses—such as pupil size, angle kappa, and angle alpha—I’m less concerned with today. With time and experience, I’ve learned that these are not as critical for success with most of the technologies we’re now using. I look for higher-order aberrations and things like coma and trefoil. I want to know if it’s a complex cornea, because that also will guide some of my choices.
OM: Which systems and formulae do you use for preoperative planning?
CM: My team uses the ZEISS Veracity digital system to gather all the data for preoperative planning. (This can also be done with Bausch + Lomb’s Eyetelligence system or Alcon’s Cataract SMART Suite.) We then choose the formulas we feel would best fit the patient’s demographics and the biometry of their eye, and the lenses that we feel would best suit the patient’s needs and ocular health. We can then manipulate different choices to find the best overall match for the patient.
Today we have very sophisticated nomograms as well. The most widely used seems to be the Barrett Universal formula. There are variations on that formula for use with keratoconus, post-LASIK patients, post-RK patients, and more complex analyses. The radial basis function (RBF) is a fourth-generation formula that is very useful, and ZEISS has an AI nomogram that also gets really great results, especially in short eyes. So, we have many ways of finding the best IOL power and the best targeting of the postoperative refraction for our patients.
OM: Are there additional tests, scans, or treatments that you use for particular types of patients or in certain circumstances? If so, why?
CM: For all our patients, we separate the biometry visit from our evaluation of the patient. We do that so we can maximize the ocular surface health prior to doing biometry. Normally, that entails warm compresses with a nutraceutical in the preoperative evaluation. If they have more severe dry eye, we might add other treatments, such as a prescription immunomodulator like lifitegrast or cyclosporine, or we might add an evaporative tear barrier like perfluorohexyloctane ophthalmic solution (MIEBO; Bausch + Lomb) or something a little bit more intensive that the patient will be able to maintain in the postoperative period, when their dry eye is likely to be more severe.
There are circumstances where the patient is more complex and warrants further testing. In those cases, we have the patient come back for biometry on that separate visit, and if we don’t get high-quality and consistent data, we’ll bring the patient back on another date as well. Or, if we see that the patient has an irregular ocular surface, we may do further testing—especially in patients who have corneal scarring; post-RK patients [in whom] we want to get serial measurements so we can achieve some consistency; former hard contact lens-wearers, so we can make sure that their cornea is as relaxed as it can be after they’ve discontinued use of their contact lenses; and post-LASIK and post-corneal-refractive surgery patients.
If I see that the corneal shape is irregular, I may have them come back for an iTrace test (Tracey Technologies) so we can see the effect of decreasing the aperture size, as these patients may benefit from Apthera (Bausch + Lomb), a small aperture IOL. I particularly like this iTrace program because it shows the quality of the image as I decrease the aperture on the evaluation, mimicking what happens as I decrease the aperture of the Apthera lens. With its refractive forgiveness of about a diopter of spherical equivalent and one and a half diopters of cylinder, I prefer a small-aperture solution for my post-RK patients. Having that preoperative measurement is very helpful in educating the patient and in making the decision to use that technology.
Once we’ve done all of this, I understand the patient’s needs, current health, and possible future health, and we have all of our planning done with the geometry of the eye and the data that we were able to obtain preoperatively. The next step in optimizing our outcomes is to take that data into the operating room.
OM: How do you set patients’ expectations of IOLs?
CM: Everything after the age of 40 is a compromise. It’s important to convey that compromise is always necessary with cataract surgery, no matter which solution we decide to use. None of the technologies we have available is as good as an emmetropic patient in their 20s, who can see clearly from distance to near without any increase in visual disturbances like glare, halos, or starbursts. At the beginning of our conversation, I tell patients, “I can’t make your eye 20 again. I can’t make you 20 again. If I could, I would be 20 again, and, clearly, I’m not.”
If a patient says, “Do whatever you can to keep me free of glasses,” then we choose the IOL that will give them the best range of vision in a healthy eye. In my experience, that is usually a trifocal or a diffractive optic. We’ll talk about that class of IOL and which of those would fit their needs best. I don’t ever tell patients they’re going to be completely glasses-free. I think it’s important to be realistic.
It’s also important to let patients know that astigmatism is already part of their eyeglasses prescription and that, without correcting it during surgery, they will still need glasses. I tell patients that surgery is the best way of correcting astigmatism because wherever they look, it’s just as well corrected; the correction within their implant moves with their eye.
OM: How do you approach surgery on astigmatic patients?
CM: I automatically treat the astigmatism with the spherical equivalent of the refractive error for distance—it’s part of my process of treating for the maximal visual quality after cataract surgery. I will have a plan to treat with a toric lens or a limbal relaxing incision using a femtosecond laser platform, or sometimes a combination of those.
Being able to reliably align astigmatism treatment during cataract surgery is the next most important thing for maximizing outcomes. In the past, I would take the patient to a slit lamp in the preoperative area. The slit lamp had a gauge, so I knew exactly where the slit beam was located, on which axis, and I would position the patient with their head perfectly upright. Then, with a cystotome and a sterile pen, I would make a small perforation in the peripheral cornea, right at the axis where I needed to place the treatment.
Using cystotome to make that mark allows it to be a very tiny one, compared to putting a pen mark on the cornea. While the level of precision with that low-technology method was very good, it was labor intensive. Now I have the Callisto (Zeiss) eye digital marking system, which uses a preoperative image obtained by the IOLMaster 700 (Zeiss) to register the patient under the microscope. Alcon’s ARGOS Biometer works similarly.
The Lensar ALLY Robotic Cataract Laser System also does something similar, but in the laser suite, where a preoperative image from a Pentacam (Oculus), a Cassini Ambient, or an IOLMaster 700 is used to register the eye under the laser. The limbal relaxing incisions are oriented at the proper axis, or very small nubs are created on the edge of the capsulotomy to align the toric lens. I find this to be the most efficient and accurate method of aligning astigmatism correction.
We can also modify a plan intraoperatively. Veracity provides the ability to choose a different lens during the surgery itself, and to choose a different method of managing astigmatism, if necessary. All that information will be automatically uploaded into a template for the surgical procedure, so you can finish the surgery then immediately complete the operative note with all the information that applies to that surgery, for that patient, with that IOL.
Keeping the patient slightly in reverse Trendelenburg helps prevent an increase in posterior pressure. Be sure to remove any viscoelastic from underneath the IOL (especially with toric IOLs) to help stabilize that alignment in the early postoperative period.
OM: When complications occur, how do you manage them?
CM: It’s always useful to have other tricks in your bag. For example, if you have an anterior capsular tear, often that can be managed by orienting the IOL 90° to the tear. However, if you have a toric lens and the tear happens to be in the axis of the astigmatism, it may not be possible to simply align that lens in the same axis.
You should know what to do if you need to convert to limbal relaxing incisions instead of using a toric lens—for instance, if you’re going to put a monofocal lens in the sulcus. A more advanced way of managing a complication like that would be to do a primary posterior capsulotomy, prolapse the optic through that, and maintain toric alignment. If you have a posterior capsular tear and don’t feel secure putting the lens in the bag, there are other ways of capturing the optic. One way is to put the haptics in the bag then do a reverse optic capture through an intact anterior capsulotomy.
Prior to surgery, as part of the consent, I always communicate to the patient that we may have to make a change to the plan if something doesn’t go as expected. Afterward, as soon as they’re able to comprehend, I talk to the patient honestly about what happened and how I managed it.
OM: What factors can impact IOL stability, and how do you mitigate them?
CM: Zonulopathy can occur due to preoperative trauma, or it could be created iatrogenically during surgery. If you see some instability in the bag due to zonulopathy, that needs to be managed with a capsular tension ring or a capsular tension segment to stabilize the bag before placing the lens where we normally would put it.
I have had to do that when I wanted to keep the complex optic and the complex lens that I had planned for. Since all these lenses cannot be safely placed in the sulcus, I will go to a greater extent to maintain the integrity of the capsular bag so I can use those lenses. If that’s not possible, it’s good to have a backup that comes as close as possible to meeting the goals that you discussed with the patient preoperatively. That might mean putting in a 3-piece monofocal lens with the Yamani technique, or perhaps even using a Light-Adjustable Lens (RxSight) with a flange scleral fixation technique. It is important to have backup plans for every surgery.
OM: What is your typical postoperative management routine?
CM: I try to streamline postoperative management for my patients. In some cases, I have prescribed compounded drops so there are fewer for the patient to administer. In other cases, I have chosen a dropless regimen delivered via an intracameral antibiotic with a non-steroidal in the phenylephrine-ketorolac infusion in addition to subconjunctival triamcinolone. We conducted a study that looked at that dropless regimen vs a traditional drop regimen and saw equivalent outcomes, with similar levels of inflammation and macular edema, but with a much better patient experience.
I like to evaluate my patients’ final post-operative outcomes so I can understand whether we met our refractive target. This is another place where digital planning software like
Veracity, Eyetelligence, and Cataract SMART Suite are important. They can mine the data from our medical record, upload it, and connect it to the patient’s preoperative plan, completing the loop of information that analyzes outcomes and allows us to identify ways of improving them. It also allows us to customize our nomogram for our surgical technique, which improves overall outcomes.
With today’s technology, an extensive preoperative evaluation, and realistic patient expectations, that final visit is mostly a celebration. I love for my patients to be able to experience even better vision than they ever thought they would have! OM
