Date Published: February 4, 2019
Publisher: Public Library of Science
Author(s): Krzysztof Petelczyc, Anna Byszewska, Ewelina Chojnacka, Zbigniew Jaroszewicz, Karol Kakarenko, Alejandro Mira-Agudelo, Aleksandra Ostrowska-Spaleniak, Aleksandra Składowska, Andrzej Kołodziejczyk, Marek Rękas, Adrienne Csutak.
Clinical assessment of a new optical element for presbyopia correction–the Light Sword Lens.
Healthy dominant eyes of 34 presbyopes were examined for visual performance in 3 trials: reference (with lens for distance correction); stenopeic (distance correction with a pinhole ϕ = 1.25 mm) and Light Sword Lens (distance correction with a Light Sword Lens). In each trial, visual acuity was assessed in 7 tasks for defocus from 0.2D to 3.0D while contrast sensitivity in 2 tasks for defocus 0.3D and 2.5D. The Early Treatment Diabetic Retinopathy Study protocol and Pelli-Robson method were applied. Within visual acuity and contrast sensitivity results degree of homogeneity through defocus was determined. Reference and stenopeic trials were compared to Light Sword Lens results. Friedman analysis of variance, Nemenyi post-hoc, Wilcoxon tests were used, p-value < 0.05 was considered significant. In Light Sword Lens trial visual acuity was stable in tested defocus range [20/25–20/32], Stenopeic trial exhibited a limited range of degradation [20/25–20/40]. Light Sword Lens and reference trials contrast sensitivity was high [1.9–2.0 logCS] for both defocus cases, but low in stenopeic condition [1.5–1.7 logCS]. Between-trials comparisons of visual acuity results showed significant differences only for Light Sword Lens versus reference trials and in contrast sensitivity only for Light Sword Lens versus stenopeic trials. Visual acuity achieved with Light Sword Lens correction in presbyopic eye is comparable to stenopeic but exhibits none significant loss in contrast sensitivity. Such correction method seems to be very promising for novel contact lenses and intraocular lenses design.
Nowadays presbyopia is a genuine problem of the world’s population. There are over 900 million people aged 60 or more all over the world, and this number is expected to rise one and half times within the next 15 years.  Prolongation of the working age in the context of aging of the human eye, requires compensation of accommodation mechanism by correction with artificial lenses (or systems) enabling good quality of vision at all functional distances.  There are various spectacles designs and contact (CL) or intraocular (IOL) lenses for compensation of presbyopia due to aging or as a consequence of cataract surgery. [3, 4] Multifocal CLs and IOLs with symmetry of revolution are the most widespread and frequently used e.g. CL: Acuvue Oasys for Presbyopia (Johnson & Johnson), Biofinity Multifocal (Cooper Vision), Dailies AquaComfort Plus (Alcon), IOL: Alcon Panoptix (Alcon), Tecnis Symfony (Abbott Medical Optics). Symmetry of revolution means that their shape is fully defined by one cross-section through the center [5, 6] due to placement of annular areas of disparate power in the center and periphery or some set of diffractive rings. Another approach consists of refractive elements with angularly varying optical power, termed Light Sword Lenses (LSLs), [7–9] which are subject of this study. Although there are some designs without symmetry of revolution on the market, e.g. LENTIS MPlus (Oculentis), continuous change of optical power exhibited by the LSL is a new concept which could be used for ophthalmic applications.
The S1 Protocol was approved by the Bioethics Committee of the Military Institute of Medicine in Warsaw in April 2015 and adhered to the tenets of the Declaration of Helsinki. The only modification of the study was the resignation of the examination of younger patients (Groups I and II in the S1 Protocol), therefore the study included more patients from Group III. Written consent was obtained from all participants after they had been informed about the investigative character of the study and declared their willingness to participate.
There were 34 eyes of 34 subjects of mean age 54.6 years (min: 47 y.; max: 62 y.; SD: 4.5 y.) examined in this study. Fourteen participants were female and 20 right eyes were included. The median spherical correction was (+) 0.64 D (min: 0.00 D; max: 1.75 D; IQR: 1.00 D), whereas cylindrical (-) 0.06 D (min: 0.00 D; max: -0.50 D).
In this paper visual outcomes of the LSL as a new method for presbyopia correction of 34 recruited subjects were presented. Their uncorrected presbyopic vision (REF) exhibited substantial degradation of VA with defocus (Figs 4A and 5 and Table 1: VA tasks) while corrected with LSL near and distant vision were characterized by acceptable VA and full CS (Fig 4D and Table 1: CS tasks). In order to better illustrate properties of the LSL, LSL results were confronted to STENO task outcomes, in which pupil is artificially limited by a small aperture. Such pinhole similarly to the camera obscura, realizes imaging with the extended depth of field (EDOF) with substantially suppressed contrast. These well-known features of pinhole imaging were well illustrated in (Fig 4B and 4D and Table 1). According to obtained results, the LSL provided uniform VA in whole range of investigated defocus with medians not higher than 0.2 logMAR (20/32) (Fig 4C and 5 and Table 1: VA tasks). Moreover correction by the LSL was accompanied by high quality CS in distant and near vision (Fig 4D and Table 1: CS tasks). Quality of VA was similar to that obtained in STENO (Table 2: VA tasks, Fig 6) and contrast vision exhibited coincidence with CS obtained in REF (Table 2: CS tasks, Fig 6).