This article is more than 5 years old. Information may no longer be current.
Small-aperture IOL moves solution for presbyopia a step closer
Click Here to Manage Email Alerts
The small-aperture IC-8 IOL from AcuFocus is undergoing a phase 3 clinical trial in preparation for FDA consideration. According to John A. Vukich, MD, medical monitor of the trial, the lens delivers on the promise of a premium IOL with the ease of use of a monofocal.
“It is functionally very beneficial, well tolerated by patients and easy to use from a surgeon’s standpoint. We are one step closer to what we want to achieve with IOL solutions for presbyopia,” he said.
The concept of the IC-8 IOL relies on an ocular principle that has been known for almost 3,000 years — that is, the use of a pinhole to collimate the central light and minimize refractive errors. An annular opaque mask made of polyvinylidene difluoride and nanoparticles of carbon is embedded into a monofocal hydrophobic acrylic lens. The unfocused peripheral light rays are blocked while the central focus light rays converge and reach the retina through the central 1.36-mm aperture, enhancing depth of focus and allowing functional distance as well as near vision.
“The reason why it has taken us 3,000 years to fully exploit this optical principle is that only recently, with the latest advances of biometry, topography and other technologies, we have acquired the ability to achieve plano results with a refractive correction. Now we are able to maximize the optical property of depth of focus to enhance intermediate and near vision without degrading distance vision,” Vukich said.
Forgiving of astigmatism
Vukich has been involved in the development of the lens since its beginning and implanted some of the earliest prototypes about 6 years ago.
“My experience has been uniformly positive. Every step of the way we have been encouraged by the functionality of the lens as well as the simplicity with which it can be used. There is no learning curve. It is a lens that acts like any other single-piece hydrophobic acrylic lens, and from a surgeon’s standpoint it is very easy to use,” he said.
One advantage is that it is forgiving of astigmatism, unlike multifocal lenses that tend to amplify it, thus affecting visual acuity.
“We have to be very accurate regarding astigmatism when we implant a multifocal lens. On the contrary, with the IC-8 optical system, we can go up to 1.5 D of cylinder tolerance, and that leads to a great deal of flexibility in patient selection. Frankly, it is much easier for us to implant a lens if we do not have the burden of being absolutely spot-on with our calculations. Obviously we want to be accurate, but this lens gives us a very large acceptable area in which we can land with our refractive outcomes and still achieve beneficial results,” Vukich said.
Although the IC-8 is implanted monocularly, it does not use monovision in the traditional sense. Monovision requires alternated suppression of either the distance or near image because only one eye at a time is focusing at a given distance. With the use of this lens, the patient remains binocular at distance and distance acuity is not affected.
“Stereopsis and binocular summation are retained, and quality of vision at distance is unchanged binocularly. Neuroadaptation is easily achieved, unlike with monovision with single vision lenses. We have not come across individuals who could not tolerate this lens, and this makes it a very good alternative solution for patients who have not been successful with monovision or for those who want to achieve depth of focus but, for whatever reason, are directed away from the multifocal option,” Vukich said.
Although Vukich does use multifocal lenses, including the trifocal and extended depth of focus options, he has never been fully satisfied with the optical quality they offer. Visual aberrations such as halos, glare and “spider webs” are an inherent consequence of their optical systems and a reason for dissatisfaction in a number of patients, no matter how carefully they are selected.
“The very issue of having to carefully select patients for an implant is an admission that the implant is not a robust solution for what you are trying to accomplish. The opposite is true with this lens. You do not have to be careful about the patient you choose because it is a robust solution, it works, it is tolerant of astigmatism, it provides excellent distance vision, and near acuity is significantly improved. It is a more comfortable solution and does not need so much chair time because there is little that patients have to know and no issues they have to be warned of,” he said.
A prospective, nonrandomized study investigated the effect of photopic and mesopic pupil size on visual acuity and visual symptoms in 105 patients implanted with the IC-8 IOL. Little or no influence of pupil size was found, even in mesopic pupils greater than 5.6 mm. A European post-market study reported minimal complaints of visual symptoms and high patient satisfaction.
Small limitations
No pseudoaccommodative solution can re-create the perfect vision of a young eye, but the only limitation with the IC-8 strategy is that patients may not achieve absolute sharp vision at close distances. The lens provides a functional equivalence of about +1.75 D to +2 D. Patients who want to see small, intricate details might need to use low power reading glasses. On the other hand, intermediate vision is high quality.
“Any of the applications that are so much part of our life, such as tablets, computers and smartphones, can be used comfortably with this lens. It provides very good vision for all common daily tasks,” Vukich said. – by Michela Cimberle
- For more information:
- John A. Vukich, MD, can be reached at SSM Health Davis Duehr Dean Eye Care, 1025 Regent St., Madison, WI 53715; email: javukich@gmail.com.
Disclosure: Vukich reports he is a consultant for AcuFocus.