Surgeon Shares Early Success with enVista

By Peter Heiner MBBS, FRANZCO, FRACS

In my practice, Vision Eye Institute in Queensland, Australia, approximately 60% of my cataract surgery patients receive a monofocal IOL. I have long preferred to implant aspheric, aberration-free lenses for these patients because this type of design provides the highest-quality vision to the largest number of patients, regardless of the individual optical characteristics of their eyes. Recently, I’ve been taking advantage of a new aspheric, aberration-free IOL option — the enVista IOL.

Figure 1. Dr. Heiner implants enVista IOLs through a 2.2-mm incision using a wound-assist technique.

A main goal of the enVista development process was to equip surgeons with a hydrophobic acrylic lens that would resist the formation of glistenings, the fluid-filled microvacuoles that have been known to potentially compromise the optical clarity of other IOLs.¹ This effort is reflected in the product’s FDA-approved application in the United States, which includes labeling stating that “No glistenings of any grade were reported for any subject at any visit in the clinical study.”²

Because today’s patients tend to live years and even decades following implantation of an IOL, it has been a concern to many ophthalmologists that glistenings are a possibility, in particular with hydrophobic acrylic IOLs. It has been frustrating that no treatment could be prescribed to reduce or stop glistening formation. In my experience, when they occur, they tend to increase in number for the first 3 years after IOL implantation.

Figures 2 and 3. The pace at which the enVista IOL unfolds allows the surgeon to use the I/A tip to achieve complete removal of viscoelastic from behind the optic.

I’ve heard anecdotal stories of cases in which glistenings have necessitated IOL explantations but there’s no clear consensus as to exactly how they affect vision. Fortunately, the majority of my patients in whom I’ve observed glistenings are asymptomatic. I do have a small number of patients with a hydrophilic acrylic lens in one eye and a hydrophobic acrylic lens in the other who have complained of worse vision in the eye with the hydrophobic acrylic IOL. The only pathology I’ve detected in those eyes has been glistenings in the optic of the IOL.

My Experience With the enVista IOL

I implanted my first 20 enVista IOLs in Australia in August 2011. By July 2012, I had implanted an additional 188 of these lenses. I haven’t observed any glistenings in any of those 208 lenses. Also, my early impression is that enVista exhibits a favorable rate of posterior capsular opacification (PCO), superior to the hydrophilic lenses, which we might expect given its sharp 360° square edge. To date, I’ve only performed two Nd:YAG laser capsulotomies for patients.

In an analysis I performed of my results with the first 46 enVista lenses I implanted, 100% of eyes had best-corrected visual acuity of 20/30 or better, and 82% of eyes had uncorrected visual acuity of 20/30 or better. I implanted all of the lenses through a 2.2-mm temporal incision using a woundassist technique (Figure 1).

The enVista material has a relatively high glass transition temperature (Tg) of 28° C which contributes to a controlled unfolding in the eye. I’ve found the pace of the unfolding to be an advantage because it allows ample time for removing viscoelastic from behind the optic. I’m able to insert the I/A tip between the optic and the posterior capsule and remove all of the viscoelastic before unfolding is complete (Figures 2 and 3). While this maneuver can be tricky with other IOLs because of potential damage to the posterior capsule, I find it to be easily accomplished with the enVista. (Complete removal of viscoelastic will be even more important when a toric model of the enVista lens becomes available.) Unlike other hydrophobic acrylic IOLs, the haptics do not remain stuck on the optic. After it’s inserted into the capsular bag, the enVista centers well (Figure 4).

An Option We Can Choose with Confidence

The enVista is available in a wide range of powers from 0.0D to 34.0D, which makes it an option for a large majority of my patients. I consider it the best choice for patients who are not well suited for YAG capsulotomy, such as those who are younger or myopic. Furthermore, we’re seeing a worldwide trend of performing cataract surgery on increasingly younger people, and the enVista gives me more confidence that their lens optic will stay clear for the longest possible duration.

Figure 4. As this postoperative picture shows, after the enVista IOL is inserted into the capsular bag, it centers well.

Ultimately, when we implant IOLs, we would like them to perform as closely as possible to the healthy natural lens of the eye. The enVista brings us closer to that target. For the first time, we have an IOL that not only nicely restores refractive power but we also expect to remain clear with an absence of glistenings. Thus, it performs two critically important functions of the natural lens. All other things being equal with each of our patients, the IOL that reduces the chances that glistenings will form and adversely affect vision is the one to choose.

References

1. Werner L. Glistenings and surface light scattering in intraocular lenses. J Cataract Refract Surg 2010;36(8):1398-1420.

2. Bausch & Lomb, Inc. Data on file, 2009.

Dr. Heiner practices with Vision Eye Institute in the Gold Coast suburbs of Coolangatta and Southport in Queensland, Australia. He lectures throughout Austalia and Asia on microincision surgery.