Evaluation of Visual Function After Bilateral Implantation of EDOF IOLs

INTRODUCTION AND RATIONALE

Nowadays, the most common types of intraocular lenses (IOLs) to correct aphakia after cataract surgery consist of monofocal, multifocal or extended depth of focus (EDOF) IOLs.

Current monofocal IOLs provide one focal point which will provide the patient with unaided vision at only one distance, which necessitate the need of glasses to correct vision at all other distances.

Multifocal IOLs (mIOLs) can be divided into bifocal-, trifocal- or quadrifocal IOLs, and provide patients with unaided vision at more than one distance, causing less spectacle-dependency after cataract surgery. Although mIOLs offer better unaided near vision and less spectacle dependency in comparison to monofocal IOLs, a well-known drawback of mIOLs is the occurrence of halos and glare and the inherent loss of contrast sensitivity because of their optical design. The potential decrease in quality of vision makes implantation of mIOLs less suitable in highly demanding patients or in cases of pre-existing pathology of the visual pathway (i.e., macular degeneration, optic neuropathy, post refractive surgery).

EDOF IOLs offer an extended range of focus and enable the patient to have a wider range of unaided vision in comparison to monofocal IOLs, especially from intermediate to far, while mIOLs have shown better near vision in comparison to EDOF IOLs.

Photic phenomena like halos and glare are regarded as the most important drawbacks of mIOLs and EDOF lenses. These photic phenomena can be explained due to the optical design where either diffractive or zonal refractive technology is applied. These photic phenomena become less apparent in a few months after neuroadaptation has taken place in the majority of cases. However, these phenomena can persist in some patients and are one of the main reasons for IOL explantation.

Since intermediate vision is becoming increasingly important in day-to-day tasks due to smartphone, tablet and laptop use, a new IOL was introduced with this objective in mind. The extended depth of focus IOL provides vision at far and intermediate distances up to 60 cm. Both the Acunex® Vario and the Alcon AcrySof® IQ Vivity® IOL consist of this EDOF optic design. The Acunex® Vario IOL design includes a sector-shaped near vision +1.5D addition located on the anterior surface of the IOL. The Alcon AcrySof® IQ Vivity® IOL consists of two anterior surface transition elements: the surface transition element, which includes a slightly elevated plateau for stretching the wavefront, and a small curvature change for shifting the wavefront. The last mentioned wavefront-shaping area stretches and shifts the wavefront resulting in an extended focal range of >1.5 D.

The Alcon AcrySof® IQ Vivity® IOL is a commonly used EDOF IOL and has been used for several years offering good visual outcomes in patients. Patients who received this IOL in the Maastricht University Medical Center+ (MUMC+) are satisfied with their vision quality and rarely complain about dysphotopsias after implantation. The Acunex® Vario IOL is a new EDOF IOL. According to prior preliminary results and pilot studies, this IOL demonstrates good results, including excellent distance and intermediate visual acuity, very low levels of dysphotopsia and high levels of postoperative patients satisfaction.

Both IOLs offer extended depth of focus and have similar results according to our own experience and prior research, but there are no published studies comparing these IOLs in a randomized controlled trial. The aim of this study is to compare the optical function, side effects and patient satisfaction after implantation of the Acunex® Vario and Alcon Acrysof® IQ Vivity® IOL in a controlled double masked, randomized, prospective clinical trial.

STUDY DESIGN

Patients will be examined pre-operatively and 1 week, and 1 and 3 months postoperatively. Besides a preoperative visit at which both eyes are examined, 4 postoperative visits are included when delayed sequential bilateral cataract surgery (DSBCS) is performed: week 1 visit for the first operated eye, week 1 visit for the second operated eye, and 1-, and 3-months visits at which both eyes will be examined in the same visit. In the event that immediately sequential bilateral cataract surgery (ISBCS) is performed the week 1 visit will be combined resulting in 3 postoperative visits. In both scenario's (ISBCS or DSBCS) both eyes are examined simultaneously at 1, and 3 months postoperatively in order to minimize the number of postoperative follow-up visits for patients. Consequently, with DSBCS, at 1 months postoperatively, the first eye will be 5 weeks after surgery and the second eye 3 weeks. At 3 months postoperatively, the first eye will be 13 weeks after surgery and the second eye 11 weeks. The investigators assume that this time difference does not affect the results. At the control visits, patients will receive a general ophthalmic examination, imaging of the eye and will be asked to fill-in patient questionnaires.

The duration of the study is 18 months, based on preparation of the study in the first 3 months, the inclusion of patients into the Randomized Controlled Trial (RCT) in the following 9 months, a follow-up of 3 months after IOL implantation and analysis of the data during the last 3 months of the study.

STATISTICAL ANALYSIS

All data will be collected in Castor, an electronic data capture (EDC) system designed for medical research, and exported to SPSS (IBM Corp., USA) and/or Excel (Microsoft, USA) software packages for data analysis. For the final analysis of the data, a per-protocol analysis is used. For the analysis, only patients who have completed the originally allocated treatment (i.e. bilateral implantation of the Alcon AcrySof® IQ Vivity® IOL or the Acunex® Vario IOL), will be included.

All qualitative variables will be summarized as the distribution of frequency, absolute and percentage. For all quantitative variables, descriptive statistics (including mean [or median], SD, minimum and maximum values) will be calculated for all necessary parameters. All data will be presented as means with standard deviation or proportions with percentages. The frequency and proportion of patients with postoperative medical and lens complications, and ocular/visual symptoms will also be reported. SPSS will be used to determine the differences between groups and between pre- and postoperative assessments and evaluate whether these are equal (within the non-inferiority margin of 0.1 logMAR). T-tests for independent samples will be used to evaluate to what extent the outcomes of both study-groups are comparable, considering a non-inferiority margin of 0.1 logMAR. Further, paired t-tests will be used to analyse the changes in visual acuities between the preoperative and postoperative visits.

The student's t-test requires normally distributed variables. If this assumption is not true, the more robust non parametric Wilcoxon rank sum test or Mann-Whitney U test, when appropriate, will be used. In all tests the threshold of statistical significance will be assumed equal to p=0.05