Are premium IOLs a feasible option in eyes with pseudoexfoliation?
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Welcome to another edition of CEDARS/ASPENS Debates. CEDARS/ASPENS is a society of cornea, cataract and refractive surgery specialists, here to discuss some of the latest hot topics in ophthalmology.
This month we are going to focus on the controversy surrounding the use of premium IOLs in patients with pseudoexfoliation. These patients, like many others, may have the desire to improve their vision and be less dependent on spectacles. On the other hand, their weakened zonules increase the risk for IOL dislocation, decentration and tilt. Can a premium option be offered to them? What are the caveats and concerns? Let’s explore the issue from two different perspectives, offered by I. Paul Singh, MD, and P. Dee Stephenson, MD.
– Kenneth A. Beckman, MD, FACS
OSN CEDARS/ASPENS Debates Editor
Premium lenses can be used with careful selection
When we talk about premium IOLs, we first have to define what type of premium IOLs we are referring to because “premium” is a wide category that includes optics of different types. Secondly, we have to distinguish between patients who have pseudoexfoliation with and without glaucoma because glaucoma is the true contraindication to the use of multifocal IOLs, especially if there is significant loss of ganglion cells, nerve fiber layer or visual field. Multifocal lenses split the light and would further decrease contrast sensitivity. In addition, we do not know how aggressive pseudoexfoliation glaucoma can be, and it can be volatile in some patients.
Prior to surgery, it is important to know if the patient has been stable for many years or instead has been progressing and if the IOP is stable and well controlled or fluctuating. In the best cases, if the nerve fiber layer and ganglion cells are still fairly healthy with sufficient historical data and IOPs are at target with a manageable treatment for the patient, I might consider an extended depth of focus lens or even a multifocal IOL, while in the cases in which glaucoma is not properly controlled, I would go for the safety of a monofocal lens. This is also in consideration of the fact that patients who are on multiple glaucoma drops and/or are not undergoing MIGS at the time of cataract surgery will likely have ocular surface issues and thus more risk for dysphotopsia and contrast loss postop. With that said, in patients with glaucoma who also have significant astigmatism, I feel strongly about implanting a monofocal toric lens to maximize the image quality.
It is important to consider that pseudoexfoliation may be a source of error in the calculation of effective lens position (ELP). The zonules may be weakened, and we can sometimes only find this out at the time of surgery when we do our capsulotomy and sense how rubbery or soft that capsule is. If I sense weakness, I tend to place a capsular tension ring (CTR) in the bag. I have a low threshold for using a CTR in these patients, even if they do not have significant loss of zonules. If I have any concern about stability, I do it. Preoperatively, a smaller anterior chamber depth may indicate zonular instability in eyes with pseudoexfoliation. If the IOLMaster (Zeiss) or another biometry method indicates that anterior chamber depth is a little shallower and the lens looks anteriorly positioned, then I would be hesitant to use any kind of premium IOL because we do not know where the ELP might be after surgery.
However, we have now the Light Adjustable Lens (LAL, RxSight), which I think is a great option for a lot of these patients because it is a monofocal lens without any additional aberrations to affect quality of vision. With this lens, we let the eye heal, see where the ELP ends up and then adjust the sphere and cylinder as needed. In addition, the LAL is a three-piece lens, which tends to stabilize the bag like a CTR does. If there is an inadvertent posterior capsular tear, one can place this lens in the sulcus. I therefore tend to use the LAL in patients with pseudoexfoliation, whether they have glaucoma or not, as long as they can dilate to around 5 mm in order to deliver a proper adjustment.
In the presence of pseudoexfoliation without glaucoma, if there is not any obvious zonular dehiscence or zonulopathy, I would consider implanting a multifocal lens with a CTR for stability. In case of severe zonular instability, greater than 3 to 4 clock hours of zonular dehiscence, I use a capsular tension segment sometimes in conjunction with a CTR to stabilize the capsular bag. These patients can still do well with toric lenses and multifocal lenses, but it is important to assess the stability of the capsule during surgery if possible.
Whatever the IOL choice, patients with pseudoexfoliation must be clearly told that their condition may evolve in ways we cannot predict upfront and that problems may arise later. I tell them that they have a condition that can cause the structure of their lens and the structure of the attachment that stabilized the lens to destabilize over time. I tell them that there is a chance that we will have to take that lens out or adjust it later. However, most of my patients are happy and have not experienced significant issues, and in only a few cases have I had to replace an IOL.
If you follow these general guidelines, a premium IOL in the right patient can work well. When in doubt, if you are concerned about stability but still want something more than single-focus vision, I recommend a monofocal plus IOL. I tend to use the enVista Aspire IOL (Bausch + Lomb), which is a monofocal plus lens (toric as well) that has longer haptics (110° of contact with the capsule) that can theoretically help with IOL stability. Due to its aberration profile, if the IOL decenters, image quality is still maintained.
- For more information:
- I. Paul Singh, MD, of the Eye Centers of Racine and Kenosha, Wisconsin, can be reached at inderspeak@gmail.com.
Better to use safer alternatives
In my opinion, you have to be extremely cautious when choosing an IOL for patients with pseudoexfoliation without glaucoma because most of the time, if you follow them long enough, spontaneous dislocation of the bag-lens complex is likely to occur. There are plenty of papers out there that have reviewed whether a capsular tension ring (CTR) might help, but while the presence of a CTR seems to facilitate repositioning, there is no evidence that it might prevent dislocation. As a consequence, these patients are not great candidates for multifocal or toric IOLs because even minor misalignments of these lenses can lead to significant vision distortion.
Due to the deposition of pseudoexfoliative material at the pupillary margin, patients with pseudoexfoliation tend to have a smaller pupil that does not dilate well. If you stretch that pupil, you have to be careful and gentle because you do not want to pull on zonules that are already weak. Therefore, a premium IOL such as the Light Adjustable Lens (RxSight) is not a feasible option either because the pupils would not dilate to the minimum of 6.5 mm to 7 mm required for the light adjustment of the lens after implantation.
I perform femtosecond laser-assisted cataract surgery in patients with pseudoexfoliation, and if they have a dense cataract, I like to perform surgery sooner than in the average patient because I do not want to pull on the zonules. I dilate the pupil to 4.5 mm to 5 mm, make sure that I have plenty of viscoelastic to protect the cornea, and do a pattern that is catered and customized to that patient’s density of cataract. Although most of these cataracts break up easily with the laser, I like to use the miLOOP lens fragmentation device (Zeiss) because it causes less stress on the zonules, and I often implant a CTR to enhance stability. Then I perform the capsulotomy, out of the rim of the exfoliation, and the femtosecond laser allows me to do it nicely and precisely. Because I use femto, I much prefer to do astigmatic incisions in these patients if they have astigmatism rather than implant a toric lens because an astigmatic correction based on the cornea will not be affected in case of IOL dislocation.
To provide these patients with some degree of extended range of focus without affecting image quality, I like to use the aspheric premium monofocal IOLs of the enVista family (Bausch + Lomb). Because they have the same power from the center to the edge, visual acuity is not affected in case of tilt or decentration. To further increase the field of vision, you could also do a mini-monovision with these lenses, slightly undercorrecting the nondominant eye. With a target of –0.5 D to –0.75 D, patients will achieve great intermediate vision. So, this is a good way to provide patients with a premium outcome without putting them at risk. If they have decentration or tilt, an aspheric lens is safe.
- For more information:
- P. Dee Stephenson, MD, of Stephenson Eye Associates in Venice, Florida, can be reached at eyedrdee@aol.com.
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