November 2019

IN FOCUS

Managing Irregular Corneas Prior to Cataract Surgery
Handling patients with keratoconus who need cataract surgery


by Ellen Stodola EyeWorld Editorial Co-Director




Source (all): William Trattler, MD

 

When considering cataract surgery in patients with keratoconus, there may be certain factors to take into account before developing a surgical plan. Experts discussed treatment options for these patients, steps to take before surgery, how they decide on a plan of action, and appropriate lens options.

What are the treatment options for keratoconus and particular considerations for patients with a cataract?

The first priority is to identify whether keratoconus is present, William Trattler, MD, said. “Patients who come in with loss of vision from cataracts may also have keratoconus. The only way to find out is to perform topography,” he said. “It’s pretty shocking that some patients who we diagnose with keratoconus have no idea that they have this condition, even though they have been seeing their own doctor for years.” Dr. Trattler added that keratoconus is often identified when patients come in for a LASIK screening and are having their very first topography of their life. He added that topography is being performed more commonly than it was as decade ago, but it’s still not done by every doctor on every patient at least once. Since there are no signs on the slit lamp exam unless the patient has advanced keratoconus, the only way to identify keratoconus is with topography. Hopefully more screening topography will be performed, as this will enable patients with keratoconus to be diagnosed at an earlier stage before vision loss has occurred.
After identifying that a patient with cataracts also has keratoconus, Dr. Trattler said the next step is to consider the treatment options.
“If someone has a significant cataract along with keratoconus, you have to decide how to tackle these two conditions, and there’s no required order,” he said.
For example, Dr. Trattler said that if someone has a visually significant cataract, you could choose to perform cataract surgery first, which would significantly improve vision. Then glasses, soft contacts, or a scleral lens may be used postoperatively, depending on the level of keratoconus, to further improve the vision.
The other option, he said, is to treat keratoconus first. Crosslinking will strengthen the cornea and typically will help improve the corneal shape over time. “The problem is that the change in shape will develop over months to years rather than in weeks,” he said. So, while crosslinking is an effective treatment for patients with keratoconus, the improvement in corneal shape is slow. “It is helpful, especially in patients who have documented progression of keratoconus despite their advanced age,” Dr. Trattler said.
Another option that is favored by a subset of surgeons, he said, is to use Intacs (Addition Technology) to reshape the cornea, which can help in some cases, but it varies on a case-by-case basis.
And a third option is topography-guided PRK with Contoura (Alcon), which Dr. Trattler said is now available in the U.S. This technology will reshape the cornea to a more normal, less irregular shape, he said, adding that he’s looking forward to seeing more data on its effectiveness in keratoconus.
Anthony Aldave, MD, noted that when he is treating a keratoconus patient with significant irregular astigmatism, his plan of action is to refer for a rigid gas permeable or scleral lens or to perform a corneal transplant. In keratoconus patients who will need cataract surgery, he stressed that the most important step is choosing the correct IOL power.
Kenneth Beckman, MD, stressed the importance of optimizing the ocular surface before any treatment decisions are made and also ensuring the patient is out of their contacts ahead of the preoperative evaluation. Once you’re past the hurdle of cleaning up the cornea, he said there are several options. First of all, you need to take into account that the measurements that we take may not be entirely accurate particularly in a very steep cornea, he said. “In my experience, we tend to see, in severe corneas, that the topography can really fluctuate, and you tend to find a hyperopic surprise in postop refraction,” Dr. Beckman said. Therefore, he usually targets slight myopia in these patients to get them closer to plano.
If you’re going to be doing a premium procedure on a patient, you have to take into account that the accuracy, forgetting about all the aberrations of the lens, of the power calculation may be off, he said.
Intacs, crosslinking, or topography-guided ablations are all good options, Dr. Beckman said, adding that he personally does not use topography-guided ablation at the time of crosslinking, because he doesn’t know if the cornea is going to change. “I would rather treat the cornea, let it stabilize, and then see if they need refractive surgery later,” he said.
Dr. Beckman pointed out that Intacs do not slow progression, but they can significantly reshape the eye. “Their benefit is correcting residual astigmatism to give a patient better uncorrected or spectacle corrected vision,” he said.
Crosslinking is going to remodel the cornea for months and months, Dr. Beckman said. “I’d probably lean towards getting the cataract out and seeing where I am and then determining if I want to crosslink,” he said, adding that if you had a pediatric cataract and the patient is progressing rapidly, you may want to crosslink first and then do that cataract.
When there are this many options, it’s because none of them are perfect, Dr. Beckman said, but he believes the techniques are getting better and insurance coverage is getting better, so there’s more access.

Which lens options are available for these patients?

When looking at lens options for these patients, Dr. Aldave said that if the patient was satisfied with glasses-corrected visual acuity prior to the development of the cataract, he will usually place a monofocal IOL targeting emmetropia based on the measured keratometry values. However, if the patient is a contact lens wearer or may need a corneal transplant in the future, he usually places a spherical monofocal IOL targeting emmetropia based on his average keratometry values after a corneal transplant.
Dr. Aldave said he personally does not use toric lenses for patients with keratoconus but noted that these lenses may be used in the setting of topographic stability, orthogonal astigmatism, and in patients who are not rigid gas permeable or scleral lens wearers. Dr. Aldave does not recommend the use of multifocal IOLs for keratoconus patients.
Dr. Beckman agreed that he’s “not a big fan” of a multifocal lens in these patients. Potential problems are the obvious aberrations from the cornea, the cornea may be changing, and you also may be “way off in power just by virtue of the inaccuracy of their measurements preoperatively.” For this reason, Dr. Beckman said this choice would be a riskier option, but some doctors may choose this option if the astigmatism is mild.
Dr. Beckman said that a toric lens is an option that he has used in patients with keratoconus. “But you want to make sure they’re fairly regular and fairly stable,” he said. “A lot of these patients have a lot of astigmatism, and you may not be able to fully correct the astigmatism with a toric.” He added that the patient may appreciate the option of debulking the astigmatism with a toric and then wearing weak glasses or contacts.
“The concern is if you put a toric lens on these patients, they may then may not be able to wear a gas permeable or scleral lens,” Dr. Beckman said, adding that those lenses correct all of the corneal astigmatism (but some of that has been corrected inside of the eye) so you might get an overcorrection with the contact lens.
For patients with keratoconus, a multifocal will not be effective, Dr. Trattler said. “They already have a multifocal cornea, so you want to avoid a multifocal or EDOF lens.”
If the astigmatism is irregular, astigmatism-correcting IOLs are often not the best option for patients with keratoconus, Dr. Trattler continued. Toric IOLs can be used if the astigmatism is regular but not if there’s a significant skew in the axis. If the axis is skewed, there is no clear axis to orient the toric IOL, he said.
Dr. Trattler said that you also have to consider if the patient wears a scleral lens, RGP lens, or hybrid lens and plans to continue to wear one after cataract surgery, then a toric intraocular lens is not the best plan of action. A monofocal lens will be the better option, but Dr. Trattler said to choose one without negative asphericity. A steep cornea means that the cornea already has significant negative asphericity, he said, and there is no need to use a monofocal IOL that provides additional negative asphericity. Instead, consider a monofocal IOL with neutral asphericity.

At a glance

• Making a diagnosis of keratoconus and ensuring the ocular surface is optimized are important first steps when treating patients with both keratoconus and cataracts.
• Experts said that multifocal lenses may not be the best options for patients with keratoconus, but monofocal or toric lenses could be used.
• Options for treatment of keratoconus include crosslinking, Intacs, and topography-guided PRK.
Often the treatment plan may need to be decided on a case-by-case basis for these patients who also have a cataract that needs to be addressed.

About the doctors

Anthony Aldave, MD
Professor of ophthalmology
Walton Li Chair in Cornea and Uveitis
Chief, Cornea and Uveitis Division
The Stein Eye Institute, UCLA
Los Angeles

Kenneth Beckman, MD
Columbus Eye Surgery Center
Columbus, Ohio

William Trattler, MD
Center for Excellence in Eye Care
Miami

Relevant financial interests

Aldave: None
Beckman: Avedro
Trattler: Avedro, CXLO, Oculus

Contact information

Aldave
: aldave@jsei.ucla.edu
Beckman: kenbeckman22@aol.com
Trattler: wtrattler@gmail.com

Handling patients with keratoconus who need cataract surgery Handling patients with keratoconus who need cataract surgery
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