The Light Adjustable Lens Has Come a Long Way

by | March 2012

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In development for more than a decade, the light adjustable intraocular lens (LAL®; Calhoun Vision, Inc.) is approved for use in Europe and is in Phase III clinical trials in the United States. Based on clinical results and almost 4 years of commercial experience in Europe, the LAL has the potential to make the refractive outcomes of cataract surgery outcomes as predictable as those of LASIK.

Cataract surgery has improved markedly over the last decade, but even with advanced biometry and the most sophisticated lens power formulas, 50% of patients are left 0.50 D or more from emmetropia. Despite high expectations, only about one-third of cataract patients have 20/20 uncorrected vision following standard monofocal IOL implantation.

The goal of the LAL is to literally make cataract surgeons into refractive surgeons, giving them a tool to bring the great majority of patients to emmetropia without additional surgery. The outcome predictability derives from the fact that the adjustment of lens power occurs after implantation, when the eye has healed and achieved refractive stability.

The LAL

The LAL is a silicone IOL that is similar in appearance to other three-piece IOLs (Figure 1). The primary difference is that it is made out of a photosensitive silicone that when subjected to ultraviolet (UV) light changes the power of the lens. Focusing a specific pattern of UV light on the implanted lens causes it to change shape, allowing the surgeon to correct sphere and cylinder.

Depending on the pattern of light and the area of its surface to which the light is selectively directed, the LAL can be made to locally flatten or steepen. The curvature can be changed across the lens to increase or decrease sphere power, or it can be precisely steepened and flattened in two perpendicular meridians to correct astigmatism.

The LAL in a Changing Environment

The LAL was first announced more than a decade ago, and in that time much has happened in cataract surgery. Multifocal and accommodating IOLs have gained traction, femtosecond lasers have entered the market, and surgery has become more accurate, with better imaging, biometry, and IOL calculation formulas.

Rather than reducing the need for the LAL, these advances make the LAL more attractive. First, all of the technologies that have helped improve cataract surgery outcomes have also raised expectations for both doctors and patients. In addition, with all their new tools, cataract surgeons are beginning to think like refractive surgeons and are working hard to give patients the best possible uncorrected postoperative vision. This mindset should make the LAL highly appealing.

Further, while all this new cataract surgery technology is attractive, it is also expensive; but the LAL promises to be highly cost effective. For a comparison, take the femtosecond lasers that have been applied to cataract surgery. The femtosecond laser is a very expensive device to buy, maintain, and use; in exchange for this cost come improvements in the surgical procedure, but only a slight enhancement of the refractive outcome.

In contrast, the acquisition cost of the LAL technology is much less, but it provides a readily measurable, very significant improvement in outcomes.1 For surgeons whose budgets permit only one big-ticket purchase, the LAL should prove very attractive.

Current Status

Multiple technical challenges have kept the LAL in development for a long time. The chemistry of the lens is complex, and there have been a number of engineering issues to overcome in creating the exceptionally precise light delivery device (LDD). In addition, a new silicone lens material and the intraocular use of UV light both raise potential safety issues; and much time was consumed in testing to demonstrate that the LAL procedure is as safe as traditional cataract surgery.

At this time, the LAL is approved in Europe. The device is in commercial use there and at test sites elsewhere. The approval processes in Canada and Mexico are well advanced, and we hope that approval in those countries is not far off. At this point, thousands of procedures have been performed in Europe and the volume is growing.

Two things are driving acceptance of the LAL among European surgeons: first, with the LAL a single surgical procedure can almost always ensure a satisfying refractive outcome. To get the same level of accuracy with other advanced IOLs—including presbyopia correcting, premium monofocal, and toric lenses—will often require LASIK, PRK, or incisional surgery. Second, surgeons are compensated at attractive levels by private pay patients for the LAL because there is extra work involved.

Getting Started

The first thing a surgeon needs to do to begin working with the LAL—in countries where it is approved—is to gain access to the LDD (Figure 2). At present, the device costs roughly €100,000 ($131,000) in Europe. (It is not yet for sale in the US). The LAL costs about the same as other advanced IOLs.

Beyond that, surgeons have to be trained to use the lens inserter. Most lenses have their own inserter, and the LAL is no different. Proper use of the LDD also has to be learned, but it is not challenging.

Most of our European surgeons are charging substantially more for the LAL compared to multifocal or accommodating lenses. They position the LAL as a “super premium” IOL. They have no trouble charging more because patients perceive that the LAL gives them a much better likelihood of getting excellent vision.

The Patient’s Experience

The LAL provides a great experience for patients. Their cataract procedure is the same as everyone else’s, but 2 weeks after surgery, instead of giving the patient a prescription for glasses or a talk about how LASIK or PRK will be needed, the surgeon uses the LDD to adjust the lens power. Patients do have to wear UV protective glasses until the lens is adjusted and locked in, but compliance has been outstanding in Europe and there have been very few complaints. On adjustment day, the patient comes in with mediocre vision, has the light adjustment, and by that evening sees a dramatic improvement in acuity.

It is a truly exciting experience for the patient, much like that of LASIK, in which patients come to surgery with poor vision in the morning and are able to see well by the evening. For IOLs that are not light adjustable, the same correction is possible with the addition of LASIK, PRK, astigmatic keratotomy, or limbal relaxing incisions; but those are all more complex and invasive surgical procedures, each with a set of possible complications. The LAL is adjusted, non-invasively and quickly, with just light.

Going Forward

In the US, Phase II trials of the LAL have been completed, and these met their endpoints for both efficacy and safety. Phase III trials are underway. The Phase II trial tested correction of myopia and hyperopia; the Phase III trial will test these with or without astigmatism correction. We expect to enroll 600 LAL eyes in the study and plan on 1 year of follow-up.

Goals for the next 5 years include getting regulatory approval in selected countries around the world. We hope to get US approval after a successful completion of the FDA trial, and regulatory clearance well before that in Canada and Mexico. Subsequently, we may pursue regulatory approval in South America and Asia. The last approval is likely to be in Japan, which, although a large market, has a very rigorous regulatory process.
 

THE BOTTOM LINE

The LAL is approved and available in Europe and, if approved, may be available very soon in Canada and Mexico. Phase III clinical trials are underway in the US. The LAL offers surgeons a nonsurgical means to give cataract patients high quality postoperative vision, even when the initial surgery leaves them a diopter or more away from the target refraction and even when they possess up to 2.00 D of corneal astigmatism.


Robert K. Maloney, MD, MA (Oxon), is a clinical professor of ophthalmology at UCLA and director of the Maloney Vision Institute, in Los Angeles, CA. Dr. Maloney is a consultant and equity holder for Calhoun Vision. Refractive Eyecare senior editor Ying Guo, PhD, assisted in the preparation of this article.
 
 
 
 
 
Reference
1. Hengerer FH, Hütz WW, Dick HB, Conrad-Hengerer I. Combined correction of sphere and astigmatism using the light-adjustable intraocular lens in eyes with axial myopia. J Cataract Refract Surg. 2011 Feb;37(2):317-23.
 



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