Abstract
Purpose :
Low illumination conditions induce changes in the visual perception such as loss of visual acuity, glare increase or night myopia. Recently, a new lens design has been proposed to improve mesopic vision that provides a slight negative defocus in a small region just above the DRP. The goal of this study is to compare the mesopic visual function of users wearing general-use lenses and lenses optimized for mesopic vision.
Methods :
56 subjects participated in this observational, prospective and double-masked trial. Visual function in mesopic-illumination conditions after 15 minutes of dark adaptation was evaluated while users were wearing 2 different lenses: A) General-use design with standard power distribution and anti-reflective coating (control lens) and B) Special design developed ad-hoc for this study and characterized by a region with a slight negative defocus above the fitting cross and blue-light filter (test lens). Participants under 45 years of age tested single-vision lenses (Group 1, n=26) and subjects over 45 years of age tested progressive lenses (Group 2, n=30). Parameters analyzed were low-contrast undistorted distance visual field (VFm) using a rotating platform, and glare recovery time after flash (Gt). In addition, subjects were asked to use both pairs of lenses for 7 days and rate their general subjective satisfaction (SS) (scale 1-5) and select their preferred design for driving. Statistical analysis was performed using Statgraphics Centurion XVI.II software.
Results :
Clinical assessment revealed that lenses optimized for mesopic vision provided significant wider VFm and lower Gt for both groups. SS was significantly higher for group 1. (table 1). Preference for driving was higher for lenses optimized for mesopic vision. These lenses were preferred by 59% of wearers from group 1 and 58% from group 2 compared to 21% and 27% whose preferred standard lenses.
Conclusions :
A new lens-design concept characterized by inducing a slight negative defocus above the fitting cross and incorporating blue-light filter, improved mesopic visual function. These lenses provided wider undistorted distance visual field, lower glare recovery time and higher user satisfaction in general, and specifically at driving.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.