Presbyopic intraocular lenses
How does one make a selection?
There has been a recent boom in the number of presbyopic intraocular lenses (IOLs) made available to surgeons and their patients. So how does one make a selection? Rita Mencucci MD, Eye Clinic, University of Florence, Italy, and her team conducted a prospective trial in which each of three lenses was implanted bilaterally in 20 patients with cataract, for a total of 60 patients, with a mean age of 75 years. The operations were performed separately, always within 30 days of each other.
The lenses included in the study were the Zeiss AT LISA trifocal 839MP lens, the Alcon AcrySof® IQ PanOptix trifocal lens, and the Abbott TECNIS Symfony® Extended Depth of Focus (EDOF) lens.
The AT LISA (Zeiss) is a single-piece, preloaded, aspheric, diffractive lens with +3.33D near addition and +1.66D intermediate addition at the IOL plane.
Alcon’s Acrysof IQ PanOptix has a non-apodized trifocal design with an intermediate focal point at 60cm, which is approximately arm’s length, said Dr Mencucci.
Whereas trifocal IOLs split light into several distinct foci, EDOF lenses feature a novel pattern of light diffraction that elongates the focus of the eye, resulting in an extended range of vision.
“The design of Abbott’s Symfony EDOF lens is optimised to achieve constructive interference of light from different zones, thereby elongating the focus,” explained Dr Mencucci.
The goal of an EDOF IOL is to smooth out the defocus curve, offering an extended point of focus. Furthermore, the lens’ correction of the chromatic and spherical aberration aims to improve contrast sensitivity via achromatic technology for the correction of longitudinal chromatic aberration. The Symfony EDOF is a diffractive IOL.
Patients were examined one month after the second surgery to measure corrected and uncorrected visual acuity (VA) at near (40cm), intermediate (80cm) and distance.
At three months postoperatively, photopic and mesopic VA (MNREAD Acuity Charts), reading speed and contrast sensitivity (Optec 6500 Vision Testing System) were measured, and a satisfaction questionnaire was administered.
At both follow-up visits, all patients had significant improvement in corrected and uncorrected VA at all distances. All patients also showed good contrast sensitivity and reading performance without correction.
There were, however, measureable differences between the IOLs’ performances. The trifocal IOLs provided significantly better performance in uncorrected near VA measurements than the EDOF lenses, reported Dr Mencucci.
She added that contrast sensitivity was better in patients who had received the TECNIS Symfony IOL implant than in those with the trifocal IOLs. This improved contrast sensitivity is presumably due to the lens’ correction of chromatic aberration.
“We measured no differences in reading performance between the three IOLs,” she said.
The MNREAD examination measures the smallest print size read without significant errors; the smallest print size read at maximum reading speed; and the absolute maximum reading speed in words per minute.
The satisfaction questionnaire revealed that 97% of patients were fully satisfied, reporting good VA at far and intermediate distances. But what about patients’ spectacle independence? This is ultimately a primary goal of presbyopia-correcting IOLs. Some 67% of trifocal patients and 60% of EDOF patients were fully independent of near correction, said Dr Mencucci.
Were there any side effects? Approximately 70% of patients in each group perceived mild halos, but these were reported as not disturbing, she said.
“All the IOLs tested in this study provided very good far and intermediate VA. The primary advantage of the trifocal IOLs from Zeiss and Alcon was the superior near VA. However, Abbott’s EDOF lens provided better contrast sensitivity,” said Dr Mencucci.
Rita Mencucci: email@example.com