Accommodating IOL approved, improves depth of focus

A fourth-generation version of the only accommodating IOL available in the United States (Crystalens HD, Bausch & Lomb) was approved by the FDA on June 30. Bausch & Lomb began shipping the lens the week of July 7. According to one of the clinical investigators in the premarketing clinical trial, the lens represents an important step for patients with cataract(s) who are interested in receiving a presbyopia-correcting lens.

"Now, surgeons who have been implanting previous generations of this accommodating IOL can even more reliably offer patients good uncorrected near vision and do so with less need for myopia in the nondominant eye," said John A. Hovanesian, MD, a private practitioner in Laguna Hills, CA, specializing in cornea, external ocular disease, and refractive surgery. He also is clinical instructor, Jules Stein Eye Institute, University of California, Los Angeles.

The lens is built on the platform of the third-generation IOL (AT-50 crystalens, Bausch & Lomb). Like its predecessor, the new lens has a 5-mm optic, but there is a proprietary optic design modification that increases depth of focus. As demonstrated by results in the FDA clinical trial, the modified optic improves near vision without compromising intermediate or distance vision or inducing dysphotopsia or night-vision symptoms.

The premarketing trial enrolled a total of 125 primary eyes with a visually significant cataract, less than 1 D of corneal astigmatism, and the potential for best-corrected visual acuity (BCVA) of 20/25 or better in both eyes. The implant used in the study was actually built on another platform of the accommodating IOL (AT-45 crystalens, Bausch & Lomb), which features a 4.5-mm optic and has poorer predictability than the third-generation lens with the 5-mm optic, Dr. Hovanesian said.

The FDA requested that the visual acuity data be analyzed only for patients who were within 0.5 D of their intended refractive target at 4 to 6 months after surgery. Among 60 eyes that fulfilled that criterion, 55% achieved near uncorrected visual acuity (UCVA) of J1 or better at near and 80% achieved J2 or better. Distance UCVA was 20/32 or better in 87% of eyes, and 80% saw 20/20 or better at intermediate unaided. With distance correction, rates of 20/20 or better vision at distance and intermediate were 87% and 83%, respectively, and 70% of patients saw J2 or better at near with distance correction.

Dr. Hovanesian proposed that posterior capsule opacification (PCO) and/or the presence of pre-existing subclinical macular disease might explain why less than 100% of eyes achieved 20/20 or better distance-corrected visual acuity.

"We don't think failure to achieve the 100% level is really related to the optic," he said. "Rather, it is pretty typical for patients with accommodating lenses and even diffractive presbyopic IOLs implanted to become symptomatic from PCO earlier than patients with a monofocal IOL implanted."

Quality of vision was evaluated with contrast sensitivity testing both with and without glare. Results were similar in a subgroup of 10 eyes with the new lens implanted and a comparator group of 10 eyes with the earlier lens (AT-45) implanted.

"Extensive market research has clearly indicated that patients and surgeons alike are asking for a truly accommodating IOL as their choice of lens," said Michael Judy, chief marketing officer at Bausch & Lomb Surgical. "With these results, where patients reported getting one more line of near vision, we are coming ever closer to meeting the desired need for an optic that does provide truly good near vision without compromising the quality of vision at intermediate or distance."

Practical considerations

The appearance of the new lens, its power calculation, and insertion technique are all identical to a premium IOL (crystalens 5-0, Bausch & Lomb), Dr. Hovanesian said.

"Even under the operating microscope, surgeons familiar with the previous generation of this accommodating lens will not be able to tell the difference in the optic no matter how carefully they look, and everything about the handling of the [lens] is also the same," he said.

The only difference in use would be in the refractive target, although surgeons may decide to use their early experience to determine outcomes in their own patients before modifying their approach, Dr. Hovanesian said.

"With the previous generation of this accommodating IOL, surgeons would typically aim for a refractive outcome of -0.7 D in the nondominant eye in order to achieve spectacle independence," he said. "As a starting point, we would recommend continuing to aim for a similar target. However, surgeons will likely soon find that they can back off to a target of -0.3 or -0.4 D in the nondominant eye or even choose to target emmetropia bilaterally."

Consistent with the results from the multicenter clinical trial, the new lens outperformed the previous platform (AT-45) as well as diffractive multifocal lenses in previous laboratory testing that assessed contrast sensitivity objectively using the modulation transfer function. The lens also has been shown to have less emerging wavefront error than a previous lens (AT-45SE, Bausch & Lomb).

"The progressive improvement in accommodating lenses is one of the most exciting developments in ophthalmology, and we expect to see use of this technology increase over time as accommodating IOLs become favored over multifocal implants for patients seeking spectacle independence after cataract surgery," Dr. Hovanesian concluded.