March 2016

 

REFRACTIVE SURGERY

 

Presentation spotlight

New generation of IOLs to correct presbyopia


by Louise Gagnon EyeWorld Contributing Writer

 
   
FineVision trifocal diffractive IOL

FineVision trifocal diffractive IOL
Source: Sheraz Daya, MD

Surgeon discusses a multitude of IOL options for presbyopia correction at the Walter Wright Symposium in Toronto

Speaking at the 55th annual Walter Wright Symposium in Toronto, Sheraz Daya, MD, medical director, Centre for Sight, London, said that most well-selected patients who receive IOLs to treat presbyopia are very satisfied with their outcomes; a minority will complain of issues like difficulty driving at night.

About 10% of patients initially complain of night vision trouble, but this becomes less of a problem as they adapt, Dr. Daya said. We have very good lenses that improve the range of focus. Dr. Daya, speaking about diffractive lenses and division of light energy, questioned if it is necessary to have 100% energy at a single focal point and asked to what degree energy is reduced by the presence of cataracts.

Do we need 100% for both reading and distance? Dr. Daya asked. The reality is that 100% is not required. Reviewing the history of IOLs developed to correct presbyopia, Dr. Daya noted that the performance of accommodative lenses could theoretically improve with the inclusion of a dual-optic design linked by spring haptics, citing the Synchrony dual-optic accommodating IOL (Abbott Medical Optics, Abbott Park, Ill.) as an example of such an IOL. The Synchrony IOL, however, has not stood the test of time in performance and seems to have fallen out of favor, Dr. Daya said. The WIOL (Medicem, Prague) is an accommodative IOL that is made of hydrogel and presents advantages such as glare-free optics, resistance to posterior capsule opacification, position stability, and improved uncorrected vision at far, intermediate, and near distances. Despite the lens being large (7.0 mm partially dehydrated), it is implantable through 2.6 mm and in the bag grows to full size at 9.0 mm. The view into the eye at a dilated examination is exceptional, Dr. Daya said.

Other IOLs that have been used to correct presbyopia include zonal, refractive lenses such as the M-Plus (Oculentis, Berlin). It acts like a bifocal lens, Dr. Daya said, noting the SBL-3 (Lenstec, St. Petersburg, Fla.) is similar in design. The asymmetric shape of the M-Plus created poor optics for patients, who complained of diplopia as well as glare at night and difficulty with night driving, said Dr. Daya, who has implanted 248 such lenses. The solution he put forth was to place the lens in an upside down position so that the glare would go upward and away from the road, but his patients then reported that they did not have good near vision.

Trifocal diffractive lenses include the FineVision (PhysIOL, Liege, Belgium), the AT LISA Tri (Carl Zeiss Meditec, Jena, Germany), and the PanOptix (Alcon, Fort Worth, Texas), and they are developed using the Huygens-Fresnel principle whereby the plane wave is changed into an infinity of secondary spherical waves after diffraction.

In terms of diffractive steps, the width of the step determines the addition of power such that the narrower the steps are, the higher the addition of power, and the wider the steps are, the smaller the addition of power, Dr. Daya explained. In terms of energy, the step height dictates the repartition of energy between far and near vision. The higher the steps, the higher the energy, he said. Too much energy, however, will cause halos and glare. The FineVision lens, for example, is designed such that it contains higher power in the center of the lens to avoid night vision problems. However, the compromise is pupil dependency for reading, so patients may have to turn the lights up to read.

With the same step height over the whole optic surface, there is the same energy proportion between far/near, regardless of the pupil aperture. Such a lens is pupil independent, Dr. Daya said.

Appropriate diagnostic tools are vital in managing astigmatism that can accompany refractive error and must be corrected in order to obtain maximum performance from premium lenses. For toric lenses, newer models of the IOLMaster (Carl Zeiss Meditec) such as the IOLMaster 500 and 700 as well as the NIDEK AL-Scan (NIDEK, Fremont, Calif.) can be employed. Dont use older versions of the IOLMaster to determine the axis of the lens, he said. They are not good for accurately determining the axis of astigmatism. There is a higher likelihood of incorrect orientation, and as a consequence, correction will be underpowered. Corneal topography is very important in determining the magnitude and axis of correction. The Symfony IOL (Abbott Medical Optics) features an echelette design to elongate IOL focus and achromatic technology to correct chromatic aberration and improve contrast. According to data from the manufacturer, the IOL has been found to produce uncorrected binocular visual acuity of 20/25 or greater for far and intermediate vision in more than 90% of patients who received these IOLs. The same percentage achieved 20/40 uncorrected visual acuity for near vision. When patients were asked about their dependence on spectacles, the majority (97%) said they were satisfied with their daytime vision without glasses, and 84% said they were satisfied with their night vision without glasses. Mild to moderate halos and glare were reported in 22%, and some patients complained of poor visual quality.

One of the newer presbyopia- correcting IOLs is the Acriva Reviol Trifocal (VSY Biotechnology, Amsterdam), which combines numerous mechanisms and includes features such as chromatic aberration control, photoprotection, a square edge, a diffractive trifocal pattern, extended depth of focus, and pupil independence, and makes the majority of patients free of glasses, Dr. Daya said, citing data from the manufacturer. Another newer IOL designed to treat presbyopia is the NuLens (NuLens, Herzliya Pituach, Israel), which reportedly provides accommodation of 68 D.

Still another new IOL is the FluidVision IOL (PowerVision, Belmont, Calif.), which features a fluid reservoir where fluid moves back and forth through a pliable system. With any lens, Dr. Daya stressed that there is a period of adaptation, so lenses should generally not be removed too soon after being implanted even if patients report some negative feedback. Patients learn to adapt, and that usually takes 3 months and in some cases longer. They often need a lot of support, he said.

If there is any likelihood of lenses being explanted, Dr. Daya suggested avoiding laser capsulotomy.

Editors note: Dr. Daya has financial interests with Abbott Medical Optics, Bausch + Lomb (Bridgewater, N.J.), Carl Zeiss Meditec, Medicem, and NIDEK.

Contact information

Daya: sdaya@centreforsight.com

Related articles:

Future of noninvasive presbyopia treatment by Liz Hillman EyeWorld Staff Writer

PresbyLASIK for presbyopia correction by Matt Young and Gloria D. Gamat EyeWorld Contributing Writers

Options for presbyopia correction by Ellen Stodola EyeWorld Staff Writer

Presbyopia solutions on the horizon by Kerry D. Solomon, MD, refractive editor

New generation of IOLs for presbyopia correction New generation of IOLs for presbyopia correction
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