PRELEX surgery reduces need for spectacles, surgeons say
Presbyopic lens exchange blends cataract and refractive surgery, giving older patients far and near vision sans correction.
NEW ORLEANS — Presbyopic lens exchange, or PRELEX, is a refractive surgery option that can reduce older patients’ dependence on reading glasses postoperatively, according to two surgeons using the procedure.
“PRELEX stands for presbyopic lens exchange. It’s a term used to describe both cataract and pre-cataract procedures to reduce a person’s need for glasses for distance and near,” said R. Bruce Wallace III, MD, an assistant clinical professor of ophthalmology at Tulane University. With PRELEX, surgeons correct ametropias with an intraocular approach instead of corneal surgery. Optical coherence biometry, accurate IOL power calculation and astigmatic control are all used to get as close to emmetropia as possible postoperatively.
During clinical investigations of Prelex, Dr. Wallace and his colleague Kevin Lee Waltz, MD, an assistant professor at Indiana University, found they could greatly improve refractive errors for distance and near without treating the cornea.
“Inside the eye is where many aberrations are coming from in someone over the age of 50,” Dr. Wallace said. “I think we’re going to see a trend toward working on the lens, rather than the cornea, to correct errors in someone in the presbyopic age group.”
By removing a patient’s cataractous or pre-cataract crystalline lens and replacing it with the Allergan Array Multifocal IOL, both doctors have been able to correct multiple distances in the same eye at the same time, Dr. Waltz said. The surgeons have also used a monovision system with different powered silicone or acrylic IOLs in patients’ dominant and nondominant eyes. Additional refractive treatments, including corneal relaxing incisions and laser refractive surgery, may be required to achieve emmetropia.
Drs. Waltz and Wallace found they can achieve what they call “super-vision” (vision better than 20/20) for some patients by fine-tuning anomalies that doctors would not normally attend to.
The Array, the only multifocal lens currently approved by the Food and Drug Administration for cataract surgery, is not approved for pre-cataract PRELEX, so this is an off-label use of the device in the United States. In Europe, the Array has received the CE mark for treatment of presbyopia after refractive lensectomy.
Drs. Wallace and Waltz have trademarked the term PRELEX in the United States and Europe. They noted that Prelex is not limited to use with the Array. In Europe, surgeons are also using accommodating IOLs and other multifocal IOL models after refractive lensectomy.
“Europeans are pleased with their results,” Dr. Wallace said, “and our results have been excellent; in some cases, vision exceeds 20/20.”
Pros and cons
Drs. Wallace and Waltz have performed more than 300 PRELEX procedures between them since 1997. Both doctors have received positive feedback from patients.
They have had to explant only two lenses, both for the purpose of lens power exchange.
Visual disturbances such as glare and halos are common in the multi-focal PRELEX patients, Dr. Wallace said.
“Rings are permanent, it’s part of the system, but fortunately we’ve found that the visual cortical system learns to ignore the rings. Patients tend to tune them out,” he said.
It takes about 2 to 3 months for patients to fully adjust to their new visual system, Dr. Wallace said. While distance vision is almost immediate, adjusting to the near vision takes longer.
“The brain has to learn how to use near vision. However, far vision is great right away,” he said.
PRELEX patients often notice that their distance vision is better than they remember it being.
“They see things sharper and don’t need visual aids,” Dr. Wallace said.
For some patients there is no adjustment at all. Their brains easily relate to PRELEX with the Array.
“We found this in some hyperopes, because the visual aberrations that naturally occur in the hyperopic eye more closely match the multifocal lens,” Dr. Waltz said.
In fact, Drs. Waltz and Wallace said they strongly prefer to use pre-cataract PRELEX with the Array on hyperopes. Their average patient is 53 years old and is +3 D.
“We have taken the position that refractive lenticular surgery in myopia has significant dangers. We prefer to do the surgery on hyperopes, where the risk of retinal detachment is almost 0%,” Dr. Waltz said. The danger of endophthalmitis is a risk for all patients, Dr. Wallace added.
Fortunately, newer antibiotics and surgical treatments can help to dramatically improve visual results.
Patient adaptibility vital
Because of spectacle dependence that can affect some patients’ quality of life more than others, Dr. Wallace said patient selection is an important part of the PRELEX process. As with all refractive patients, candidates must be open to change and have an adaptable personality, Dr. Wallace said.
“Most candidates are active and thus have a strong desire to reduce their dependency on glasses. But patients should not always expect perfection the first time,” he said.
For instance, to correct residual astigmatism after PRELEX, some patients may require corneal relaxing incisions, he said. Some cases may also require subsequent laser vision correction.
“The hard part about PRELEX is that you’re held to a higher standard by the patient and by yourself,” Dr. Waltz said. “You’re not just aiming for pretty close targeted distance, or pretty close targeted near. You want to be spot-on distance and near. That raises the bar very high for the surgeon.”
For Your Information
- R. Bruce Wallace III, MD, can be reached at 4110 Parliament Drive, Alexandria, LA 71303; (318) 448-4488; fax: (318) 448-9731; e-mail: email@example.com. Dr. Wallace has a direct financial interest in the product mentioned in this article. He is a paid consultant for Allergan.
- Kevin Lee Waltz, MD, can be reached 8103 Clear Vista Parkway, Indianapolis, IN 46256; (317) 845-9488; fax: (317)579-7440; e-mail: firstname.lastname@example.org. Dr. Waltz is a paid consultant for Allergan.
- Allergan, makers of the Array Multifocal IOL, can be reached at 2525 Dupont Drive, Irvine, CA 92612; (800) 433-8871; fax: (714) 246-5913; Web site: www.allergan.com.