January 2016

 

CATARACT

 

Cataract surgery in eyes with compromised corneas


by Michelle Dalton EyeWorld Contributing Writer

 
 

At the end of the day, its answering the question, Would I have a premium lens implant in my eye if I had these corneal abnormalities? And if so, which one? There are times that its perfectly appropriate. There are times that it is contraindicated, and it is our responsibility to help guide the patient as we would choose for ourselves. Steven M. Silverstein, MD

 
Corneal epithelial defects

An example of dry eye with corneal epithelial defects

Fuchs dystrophy

In this example of Fuchs dystrophy, the obvious endothelial cell loss in the pupil zone is extensive. This patient is expected to have a more challenging postoperative course.

The pterygiumThe pterygium looks like it is only affecting the peripheral cornea, but it is actually causing a lot of irregular corneal astigmatism. It must be surgically removed, and the ocular surface will need time to heal before the patient can undergo cataract surgery. Source: Uday Devgan, MD

For patients with an unhealthy cornea, cataract surgery options are more limited

There are numerous causes behind an unhealthy corneaFuchs dystrophy and dry eye, among othersbut couple the corneal disease with visually significant cataract, and patients options are more limited than if the cornea had been healthy. Even after treating the corneal problem, these patients often do not achieve the level of visual recovery that people without corneal disorders do. Experts say be cautious with these patients, and expect to spend more time with them. A basic rule of thumb, with few exceptions, is that if the patient has a significantly compromised cornea, dont consider multifocals, said Marguerite B. McDonald, MD, Ophthalmic Consultants of Long Island, because to truly appreciate the benefit of a multifocal lens, the eye has to have exquisitely perfect optics. Younger patients with very mild dry eye that can be medically controlled may be an exception, but those with even the mildest form of Fuchs today are probably going to need corneal surgery down the road, and Dr. McDonald would argue against a multifocal lens. Patients with any type of corneal dystrophy or abnormality should be considered for a pseudoaccommodating lens rather than multifocal IOLs because of the additional issues of contrast sensitivity diminution, which are caused by the multifocal. Even if a superficial keratectomy is performed for epithelial basement membrane dystrophy (EBMD), there is a significant percentage of patients in whom this condition recurs, said Steven M. Silverstein, MD, founder, Silverstein Eye Centers, Kansas City, Mo.

Vance Thompson, MD, founder, Vance Thompson Vision, Sioux Falls, S.D., thinks the issue may not be so clear-cut. First analyze if it is an anterior, central, or posterior corneal issue. Can it be easily addressed with corneal scraping or a PTK? If we can take that irregularity or multifocality and remove it to make more of a monofocal cornea or an acceptable amount of multifocality, then I might consider a multifocal lens. However, if the RMS value cannot be dropped to under 0.2, then you dont want to add additional multifocality to the eye, and I would consider a Crystalens [Bausch + Lomb, Bridgewater, N.J.] because its optic is an aspheric monofocal. Multifocal lenses will amplify any abnormalities of the cornea, said Uday Devgan, MD, founder, Devgan Eye Surgery, Los Angeles, chief of ophthalmology, Olive View-University of California Los Angeles (UCLA), and clinical professor of ophthalmology, UCLA. I think multifocal lenses should always be used with caution, even with perfectly normal eyes, but you should be very careful of an eye that has any kind of irregular ocular surface. Dr. Silverstein will consider performing a superficial keratectomy with mitomycin-C to help reduce risk of a central recurrence in those with EBMD, but agrees that the potential visual outcome after cataract surgery is what drives his recommendations. We may get a refractive change as a result of the keratectomy, and that needs to be considered in the IOL calculations, he said. If the patient has a good central clearing and the rest of the cornea is healthy, advanced implants can be considered. But in cases of significant Fuchs dystrophy with 3+ guttae or more, who do not need grafts right now, I do not recommend a premium lens implant because its more likely than not that they will require a DSEK and that will change their refractive outcome, Dr. Silverstein said. Although a pseudoaccommodating lens might be an option, they may not get the true value of the lens implant long term, since they will progress. Dr. Devgan is more conservative even if the patients underlying condition is treated, surgeons have to ask if the surface is going to remain healthy or if there is a progressive disease. If theres Fuchs, in 5 years the corneal endothelium is going to look worse than it does today, he said. A toric lens could be appropriate if they have some degree of regular symmetric astigmatism, however.

Prep the patient

Patients dont understand that dry eye and Fuchs are chronic conditions that can be controlled but not cured, Dr. McDonald said, and that makes patient education not only crucial but difficult.

Some people just cant make the leap that they have to come to terms with it, just like high cholesterol or diabetes. I find a lot of patients follow my instructions for a month but dont embrace the chronicity of the disorder, so when the initial prescription runs out (in the case of dry eye treatments), they dont refill, she said.

Whenever there is more than one cause of blur, surgeons need to explain both the disease and the cataract to the patient and that multiple preop visits might be necessary before the cataract surgery, Dr. Thompson said. For Dr. Devgan, those preop visits are the most crucial aspect of the entire process. If you do a good job of explaining the issues and the slower recovery time, everything that happens postop is expected, he said. If you predict the problem, patients think youre a genius for predicting it, but if you never tell them about the potential problem and it happens, youre a bad guy for causing it. Consider the patient as well as the diseases, Dr. McDonald said. If you intervene, if youre aggressive and improve their dry eye, will they maintain that health in 23 years? Does Alzheimers run in their family? Crippling arthritis? You need to consider a controllable disease today may not be controllable in a few years. In Fuchs, maybe theyll be lucky and plateau for a few years, but they are going to get worse eventually. She also avoids multifocal lenses in these patients.

Be cautious in patients with severe ocular surface disease that cannot be controlled, Dr. Thompson said; these eyes are slightly more prone to melting. Everyone agreed that preop visits with these patients are significantly longer and more are needed compared to patients without compromised corneas. The additional visits are necessary to not only stabilize the cornea (in cases of chalazion or Salzmanns nodule), but Ill get a better biometry and better IOL calculations and be able to provide them with better potential vision, Dr. Devgan said.

And always, always, always explain to the patient that recovery times are going to be longer, their visual recovery may be more eventful than Mrs. Jones down the street (more visits, for example), and they may never regain perfect vision, Dr. McDonald said.

Preoperative plan

Because K measurements and IOL powers are almost linked 1:1, if youve got an irregular corneal surface, youre going to get worse K measurements and here is the danger. If you read the cornea as 2 D lower than it really is, it will affect the IOL power by 2 D, Dr. Devgan said. Always choose the machine with the lowest K value of all the devices you used, as that will tend to calculate a slightly higher IOL power. Then if theres any postop variant in the calculations, theyll err on the side of myopia. Some patients may not have any obvious evidence of a corneal irregularitysuch as dry eyethat affects vision.

You dont want to necessarily add a multifocal implant for that because a dry irregular tear film can be a tremendously multifocal surface, Dr. Thompson said. He added that the newer diagnostic technologies such as the HD Analyzer (Visiometrics, Terrassa, Spain) and the iTrace (Tracey Technologies, Houston) can measure the health of the tear film and provide enough information to help guide physician choices. If the tear film is rehabilitated, these technologies can quantify if its optical quality has improved enough to consider something like a multifocal lens.

Dr. Thompson said they also use laser-assisted cataract surgery in Fuchs dystrophy patients because it can lessen phacoemulsification time and thus lessen stress on the corneal endothelium.

Its not just about informed consent, Dr. Silverstein said. Its our responsibility. Its not just about handholding, its about education. At the end of the day, for me, its answering the question, Would I have a premium lens implant in my eye if I had these corneal abnormalities? And if so, which one? There are times that its perfectly appropriate. There are times that it is contraindicated, and it is our responsibility to help guide the patient as we would choose for ourselves.

Editors note: Dr. Thompson has financial interests with Abbott Medical Optics (Abbott Park, Ill.), Alcon (Fort Worth, Texas), and Bausch + Lomb. Drs. Devgan, McDonald, and Silverstein have no financial interests related to this article.

Contact information

Devgan: devgan@gmail.com
McDonald: margueritemcdmd@aol.com
Silverstein: ssilverstein@silversteineyecenters.com
Thompson: vance.thompson@vancethompsonvision.com

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Uveitis: Posterior synechiae, lens deposits, CME, prolonged post-op inflammation, and secondary glaucoma by James P. Dunn, M.D.

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Cataract surgery with corneal comorbidities by Ellen Stodola EyeWorld Staff Writer

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