Femtosecond Laser and the nanoFLEX^® Collamer^® IOL: A Happy Marriage

Precise capsulotomy and reproducible arcuate incisions help improve refractive outcomes and long-term refractive stability.

By S. Jacob Montgomery Jr., MD

I began using the nanoFLEX^® Collamer^® IOL about two and a half years ago and was immediately pleased with the quality of vision it provides for my patients. Using a blended vision strategy with this monofocal IOL, I have been able to deliver a better range of uncorrected vision than I am able to obtain using the currently available multifocal IOL platforms. The nanoFLEX produces excellent distance vision, and it exhibits a mechanism of what I believe to be “pseudo-accommodation” similar to the Crystalens that can produce excellent near and intermediate vision when used with the blended strategy, but with more predictable and stable refractive outcomes than my experience with the other premium lenses. The reasons for this are not entirely clear at this time, but it is theorized that the plate haptic design and unique characteristics of the Collamer material allow the lens to respond to the natural ciliary muscle movement during accommodation. For example, Collamer has a much higher water content (40%) than other IOLs, which makes it ultra-flexible and thus able to improve the range of focus over traditional monofocal IOLs.

Cataract surgery with nanoFLEX implantation and blended vision is a true refractive procedure, and I use this lens for 60% of my premium-channel surgeries. Last year, I introduced femtosecond laser-assisted cataract surgery into my practice, and the marriage of this technology with the nanoFLEX IOL has further enhanced my results. I can create a perfect 6-mm capsulotomy, the size I prefer with this lens, in every case. The laser has enhanced my astigmatism management as well. With laser-created arcuate incisions, I am able to successfully address up to 1.5D of cylinder. I have also added another change to my technique, which is to polish the posterior surface of the anterior capsule, which helps to keep patients’ postoperative vision stable. These improvements along with the blended vision strategy and the nanoFLEX IOL have revitalized my refractive cataract practice.

Keys to Success with nanoFLEX

No one IOL can meet the needs of every patient, so my strategy begins with listening closely to patients as they describe their lifestyle and vision goals. I know that the “sweet spot” for the nanoFLEX lens with blended vision is intermediate vision, which is extremely important to a large number of my patients. Many of them are between 50 and 75 years old and still very active. Many have hobbies like golfing or hunting. They drive at night and are tech-savvy, using smartphones and tablets routinely. I have found that multifocal IOLs are an unsatisfactory answer to these patients’ needs. They are looking for their best intermediate and distance vision and do not like even the thought of problems with night vision such as glare or halos. It is not uncommon for their intermediate vision to be 20/15 after their premium surgery with nanoFLEX and blended vision. I use multifocal lenses in fewer than 5% of my premium procedures, mostly for patients whose main activity is reading or close-up work. (About 35% of my premium surgery patients receive a toric IOL.) I do tell each patient who elects blended vision that while this strategy works for the majority of my patients with active lifestyles, there is no IOL that will eliminate the need for glasses in every circumstance, and that the times I expect some patients to need them are reading smaller print for extended periods and driving at night. Most patients are happy to be less dependent on glasses for the rest of their active lifestyles, and these minor limitations are not often an issue.

I’m often asked by colleagues how most patients can adapt to this form of “modified monovision” without an adequate trial or history of contact lens monovision. While I think from a traditional standpoint this is a valid question, it’s important to understand that blended vision is different from “classic” monovision. In general, with the former, I target the dominant eye to -0.50D and the nondominant eye for around -1.75D. That is a much smaller difference between the eyes than is typically targeted for monovision, which is usually a 2.5D or more difference. In addition, the dominant eye at -0.50D has excellent distance vision as expected but also acquires surprisingly good intermediate vision due to the proposed aforementioned “pseudo-accommodative” effect. The nondominant eye at -1.75D acquires better near acuity than anticipated and even more distance vision than expected allowing the “blended” effect to occur. As a result, patients tolerate blended vision very well, even those who may have struggled with monovision with contact lenses in the past.

I’ve had so few problems with patients tolerating blended vision that I stopped doing a free lens test (placing a +1.50D to +1.75D lens over their nondominant eye, which was popularized in the days of NearVision CK) before proceeding. In the occasional case where a patient doesn’t adapt to blended vision, I use corneal refractive surgery to re-target both eyes for either distance or near. I explain this in detail before the procedure, and the cost is included in the refractive cataract surgery package. To me and most of my patients, this “contingency plan” is much preferred to that of the multifocal IOL, which is to consider an IOL exchange, usually using a monofocal IOL with dependence on bifocals for the residual refractive error, or to keep the multifocal IOL and accept the loss of contrast and other vision quality issues that are common with these lenses. I also find the nanoFLEX to be more forgiving of mild residual refractive error. Therefore, I have had to use PRK or LASIK to treat residual astigmatism, myopia or hyperopia in only about 3-5% of my nanoFLEX premium surgeries with the femtosecond laser. This is a very low rate compared with the 10% I experience after multifocal IOLs.

I have found that the size of the capsulotomy in nanoFLEX cases should be 6 mm rather than the more common 5 mm. The femtosecond laser allows me to create a perfectly round, reproducible capsulotomy. This has reduced the anterior capsular contraction that can occur with any IOL and has been particularly common in my experience with other premium and accommodating IOLs, making the vision outcomes with the nanoFLEX more predictable and more stable than in my experience with the accommodating IOL.

In addition, I now use a capsule polisher in every premium case to polish the undersurface of the anterior capsule. This has reduced fibrosis and capsule contracture even more and therefore helped to minimize postoperative refractive shift. Occasionally in a nanoFLEX case, anterior capsule fibrosis and posterior shift of the IOL’s effective lens position induce a postoperative hyperopic shift. While anterior capsule relaxing incisions with the YAG laser can relieve this if performed early, prevention is the key. The larger, perfectly round and reproducibly central capsulotomy as well as anterior capsule polishing have reduced the incidence of this issue since I began using the femtosecond laser last year.

Polishing the anterior capsule also removes lens epithelial cells that contribute to PCO. I’m convinced that meticulous cleanup and polishing, regardless of the type of IOL used, are the main factors that reduce PCO rates, with IOL design and IOL material being secondary factors. The PCO rate I’m seeing in my practice with the nanoFLEX IOL is slightly higher than with single-piece acrylic monofocal IOLs, but not significantly different from what I see with multifocal and toric IOLs. I tend to perform YAG capsulotomy earlier in my refractive cataract surgery cases anyway, often at no charge, because any degradation in quality of vision in this group of patients is undesirable.

Happy Patients Make Happy Surgeons

For several years now in my practice, I have utilized the nanoFLEX IOL with blended vision, and combining this IOL strategy with the reproducibility and refractive technology of the femtosecond laser has taken my results and my patient satisfaction to a new level. I have used this technique on some of my most demanding and discerning patients, many for whom I would have strongly discouraged choosing a multifocal IOL. Of course, with any refractive IOL technology there can be unmet expectations, but honestly, as my staff would confirm, our post-op clinic days are more filled with happiness and cheer because we are not spending our time determining the cause for dissatisfaction in seemingly perfect multifocal IOL cases.

This overall approach has been a great addition to the surgical armamentarium in our quest to meet the increasing and often demanding expectations of the refractive cataract surgery patient. We deliver very high quality distance and intermediate vision with functional near acuity and have eliminated the vision quality issues associated with multifocal IOLs. We provide more long-term post-op refractive stability than in our experience with other premium and accommodating IOLs, and we are able to present it all as a more affordable option for patients seeking a “premium outcome” from their cataract surgery. ■

Dr. Montgomery is a cataract and anterior segment surgeon with 16 years of experience, a founding partner with Montgomery & Riddle Eyecare, PA with offices in Greenville, Clinton, and Newberry, S.C., and co-owner and medical director of The Surgery and Laser Center at Professional Park, an ophthalmic ambulatory surgery center.