Monovision LASIK: Laying the Groundwork for Success

Meticulous preliminary work is critical when correcting presbyopia with monovision LASIK.

BY DIANE DONOFRIO ANGELUCCI, CONTRIBUTING EDITOR

With the emergence of premium intraocular lenses (IOLs), clinicians have at their disposal an ever-widening range of surgical solutions to reduce their presbyopic patients' dependence on glasses. Even with these advances, however, experts say monovision LASIK is still the dominant player in the field.

"By far the most common treatment for presbyopia that is done worldwide is monovision LASIK, and it's pretty much stood the test of time," says Daniel S. Durrie, M.D., of Overland Park, Kansas. "If you find a patient who is having LASIK and they're in the presbyopia age group, this is a great option for not just correcting their distance vision, but being able to provide them some functional near vision."

However, laying the proper groundwork is key, with meticulous attention to patient selection and education as well as other factors. Experts offer these steps to help you maximize your success with monovision LASIK.

1. Weigh the Options

Obviously, patient needs are most important in determining your best option, but monovision LASIK has a number of advantages if your patient is a good LASIK candidate.

Monovision LASIK is a much less invasive option than a refractive lens exchange, and most patients won't want a more invasive procedure, says Roger F. Steinert, M.D., professor and vice chairman of clinical ophthalmology at the University of California, Irvine. "It's true that, in theory, they could get a very different optical result if they had a premium presbyopic lens, but we run into the reality that the lenses that we have available today are not perfect," he says.

"I don't really compare it to refractive lens exchange or phakic IOLs or other things because those are people who are candidates for different surgery," Dr. Durrie says. "If somebody is a candidate to have a new lens in their eye and that's the procedure of choice for them, the presbyopic IOLs are excellent examples and you can also do monovision with IOLs."

Dr. Steinert explains that few patients are candidates for conductive keratoplasty (CK) because it is largely designed for truly emmetropic patients. "Most people, in fact, who have had so-called perfect vision for most of their younger lives are low hyperopes. At the time they're getting presbyopic, they're also starting to get some blur at distance. CK has not worked out as well for correcting hyperopia for giving people distance vision. So, the vast majority of people who come in who might be candidates for monovision are either myopes, and you're going to do a bilateral LASIK anyway, or they're low-to-moderate hyperopes but within the LASIK range. There just are very few candidates for CK in my experience—at least who come in asking for it."

Colman R. Kraff, M.D., of Chicago also notes that CK is not as permanent as LASIK. "I think that just treating the emmetropic patient for monovision, making one eye a reading eye using something like CK or even using LASIK in that manner, has a very limited role. In most of those patients, the emmetropes that are in the presbyopic age group don't tolerate that very well, even when you demonstrate that to them with contact lenses."

Dr. Durrie says that he probably provides monovision correction for approximately 98% of his LASIK patients older than 43. "Patients who come to me are really interested in both near and distance vision," he says. "There's about 2% of the population that doesn't tolerate having their eyes different, and I think it's something that in those patients you do then have to focus both eyes at distance and give up some near vision, but in general the majority of people want to see both at near and distance." He only performs monovision in patients who are already presbyopic.

Others have reported lower rates of monovision acceptance, however. For example, Dr. Steinert has found that approximately two-thirds of those interested in monovision can tolerate a 1.5 diopter disparity between eyes.¹

2. Select Patients Carefully

To determine whether a patient might be a good monovision LASIK candidate, Michael T. Furlong, M.D. of San Jose, Calif., asks patients about their current vision correction. If they are presbyopic or showing symptoms of presbyopia, he suggests trying out monovision with contact lenses or a trial frame test.

Dr. Steinert asks his presbyopic patients about their activities and whether this option might help them. If a patient is serious about sports like golf, tennis, fishing or boating, or has an occupation requiring good bilateral distance vision, he or she probably won't be interested in monovision, he says. His staff also asks patients whether they have a past history with contact lens monovision and how it worked for them. "You can get a lot of information and deal with a significant number of patients from just the history level," he says.

To help patients understand the concept of monovision, Dr. Steinert explains that one eye is corrected for distance and one for near, stressing that they won't need to consciously choose which eye they need to use for distance or near. "I make sure they understand that this is a subconscious image processing that the brain is doing and the brain is just selectively paying attention to the clearer image and ignoring the blurrier image," he says.

When talking with patients, Dr. Durrie likens monovision to stereo music. "In stereo music, the speakers aren't playing the same source, but they blend together and it gives you more depth so it sounds better," he says.

If a patient is interested in monovision, surgeons often test-drive monovision by using a trial-frame simulation. "If someone can tolerate it in the trial frame and thinks it's great, then you can be sure that they're going to like it with refractive surgery because it's optically more superior than the lenses in a trial frame," Dr. Steinert says. If patients are still unsure, he moves on to a contact lens simulation.

Dr. Kraff believes having patients take contact lenses home for a monovision trial is key to a patient's success and helps patients understand how monovision works. "I always tell my patients that you need to experience life in monovision to make sure it works for you," he says.

As you assess your patients for monovision, it's critical to identify unsuitable candidates.

Dr. Furlong believes pre-presbyopic patients are not great candidates for monovision LASIK. "They're not noticing any symptoms of presbyopia yet, so if they were to choose monovision LASIK, I think they would be underwhelmed," Dr. Furlong says. He also excludes patients who previously failed monovision with contact lenses, as well as patients who want pristine, crisp vision for pursuits such as golf, or people who are truck drivers, pilots or work in other visually demanding occupations.

He also believes some type A patients may be a challenge if they have expectations that are too high. "When we test those out, they tend to see the compromise more than the benefit and they take longer amounts of chair time to explain the options in detail," Dr. Furlong says.

3. Manage Expectations

Be sure your patients know what monovision can do for them — and what it can't do.

When talking to patients, Dr. Kraff explains that monovision is a compromise that provides functional vision, allowing them to perform 85% or 90% of the tasks they need to do, but there still may be times they need glasses for reading or driving to get their best vision. He also tells them that they may experience some glare with monovision.

When obtaining the informed consent, Dr. Durrie also discusses how patients will see if they choose to be corrected bilaterally for distance. "Patients obviously have the ultimate choice, but when I tell them that if we focus both eyes at distance, you're going to have to wear reading glasses every time you read, look at your cell phone, look at your computer, sign the MasterCard check or go to a restaurant, they say, ‘I don't want that,’" he says.

Dr. Furlong also explains to patients that presbyopia is dynamic and tries to give them as much reading as they can tolerate in the close-up eye without significant symptoms so their monovision will last longer. "Having said that, we know that on average in about 5 to 10 years most patients, as long as their result was good initially and they were happy, will have more and more difficulty with their up-close vision because of progressive presbyopia." At this point, patients may choose to have an enhancement or opt to use reading glasses, but they still should be able to use their intermediate vision.

In addition, patients need to know that it takes some time to adjust to monovision, so you need to explain this upfront. Despite your efforts, however, a number of patients may need some hand-holding early after the procedure. "You check first to make sure they're healing well and they're on target, and then you just reassure them that this is the normal process that you go through with your brain adjusting and the neuroadaptation in the brain can take several months to really fully adjust," Dr. Durrie says.

4. Know What to Expect

After monovision LASIK, most patients have excellent functional vision, Dr. Kraff says. "That's the most likely outcome, just like with any LASIK patient, but as long as these people are prescreened, they'll understand what it's like. It's very rare that we have to go back and get rid of the monovision in a LASIK patient postoperatively." In those rare circumstances when the patient doesn't tolerate the monovision postoperatively, the reading eye can be enhanced and made into a distance eye. "To prevent this, we try to prescreen these people with a contact lens trial," he says. "If we didn't do that contact lens trial, we'd have a lot of unhappy patients because there's a high percentage that just don't tolerate it."

5. Fine-Tune for Success

Experts share a number of pearls they employ to keep patients satisfied.

"One of the things that we tend to do but actually has a weak correlation with happiness is the idea that you test for the dominant eye and then the dominant eye is the distance eye," Dr. Steinert says. However, he says, a substantial number of patients fare well when the dominant eye is the near eye. In the study he co-authored, 85% of patients chose the dominant eye for distance, and patients who chose this eye for near were similarly likely to accept monovision and have refractive success.¹

Dr. Durrie stresses the importance of not creating too much disparity between the eyes, preferring the term "blended vision," as opposed to monovision. "It's best to do it between a diopter and a diopter and a quarter, and then patients can function with their eyes together and not have problems with stereopsis and depth perception that happens sometimes when people try to have the eyes at 2.0- or 3.0-diopters' difference, which was done in contact lenses in the past," he says.

Dr. Steinert advises against a disparity greater than 1.5 diopters. "When you carry it further than that, the acceptance rate starts to drop off fairly quickly," he says.

In choosing the refraction for each eye, Dr. Furlong considers the patient's age, as well as occupation and leisure activities. If patients tend to spend more time on a computer with a large monitor rather than close-up reading, he says, they may not require as much monovision.

Monovision LASIK also needs to be extremely accurate. "In order to do this properly, you really have to have the best quality lasers, you have to have your nomograms adjusted so you know you're going to hit the target," Dr. Durrie says. If you miss the target in patients with blended vision, he says, you probably will have to perform an enhancement.

The need for perfection in the distance eye tends to temper some surgeon's enthusiasm for monovision, Dr. Steinert says. "Patients will tolerate some variability in the amount of near correction, and enhancements are relatively low for the near reading eye, but the distance eye, if you don't pretty much nail perfect vision, the patient will feel impaired and want it enhanced." In his study, 7% of patients who had monovision LASIK chose to change their near eye to distance, whereas 28% had enhancement of their distance eye.

6. Educate Patients

Ophthalmologists need to actively educate patients about monovision to counter possible misperceptions about the procedure. "Monovision in most people's mind has gotten a bed name," Dr. Durrie says, noting that most people associate it with contact lens monovision. Therefore, he tells patients that it's different from contact lens monovision and the disparity between the eyes will not be that significant, stressing that it's a blending procedure. "A lot more patient education is required when you're doing this," he says. "It can't be done by the counselors and it can't be done by somebody else. The doctor needs to do it." OM

Reference

1. Braun EH, Lee J, Steinert RF. Monovision in LASIK. Ophthalmology 2008;115:1196-1202.