Evaluation of a Night Spectacle Correction Concerning an Improvement of Mesopic Vision Quality

Reduced quality of vision and glare in twilight or night are frequently mentioned complaints within the optometric examination. A reason for these problems could be a myopic refractive shift in dark light conditions, commonly known as night myopia or twilight myopia. The aim of this study was to investigate whether quality of vision in twilight or night could be improved by a spectacle correction optimized for mesopic light conditions. Moreover, objective refraction in large pupils measured by aberrometry was compared to subjective mesopic refraction.

After obtaining informed consent, aberrometry was performed in a darkened room (0.1 lux). Subjective photopic refraction and visual acuity were measured before light was turned off and mesopic refraction was obtained after a dark adaptation period of five minutes. Finally, frames and lenses were fitted by a centration system. Lens grinding was executed centralized by a grinding workshop. In the course of this study, subjects were randomly assigned to wear two glasses double-masked in turn. One with photopic subjective refraction data and another with mesopic subjective refraction data. Both were worn for 14 ± 2 days each. Follow Up 1: After two weeks, participants were asked for their subjective experiences with the first correction by a visual analogue scale questionnaire. After the evaluation, glasses were changed. Follow Up 2: Two weeks later, subjective experiences were evaluated again. After visual analogue scale questionnaire, subjects were asked to compare the two glasses concerning quality of mesopic vision and subjective safety level during night driving.

Value of refractive shift (SE) when changing luminance from a photopic to a mesopic level. At Baseline, participants were not separated into arms as the Randomization Process was carried out at a later time point after participants picked up study glasses. Therefore, data are presented for All Participants in one Arm/Group.

Difference of visual acuity (monocular and binocular) in a darkened room (0.1 lux) after a dark adaption period of 5 min. with photopic spectacle correction ("classic" refraction obtained in photopic light conditions) compared to mesopic spectacle correction (correction of night myopia) Scale: logMAR visual acuity, using Landolt C optotypes. At Baseline, participants were not separated into arms as the Randomization Process was carried out at a later time point after participants picked up study glasses. Therefore, data are presented for All Participants in one Arm/Group.

Evaluation of subjective perceived vision comfort with the study and control glasses. Both glasses (study and control glasses) were tested for two weeks each. After the two weeks test, each of the glasses was evaluated. For evaluation a visual analogue scale questionnaire (Scale 0 - 100) was used. Question: How would you evaluate vision comfort with the tested glasses in dark light conditions? Answer: visual analogue scale slider from 0 (insufficient) to 100 (very good)

Evaluation of subjective perceived vision sharpness with the study and control glasses. Both glasses (study and control glasses) were tested for two weeks each. After the two weeks test, each of the glasses was evaluated. For evaluation a visual analogue scale questionnaire (Scale 0 - 100) was used. Question: How would you evaluate vision sharpness with the tested glasses in dark light conditions? Answer: visual analogue scale slider from 0 (insufficient) to 100 (very good)

Evaluation of subjective perceived glare sensitivity with the study and control glasses. Both glasses (study and control glasses) were tested for two weeks each. After the two weeks test, each of the glasses was evaluated. For evaluation a visual analogue scale questionnaire (Scale 0 - 100) was used. Question: How would you evaluate glare sensitivity with the tested glasses in dark light conditions? Answer: visual analogue scale slider from 0 (no glare) to 100 (strong glare)

Evaluation of subjective perceived driving safety sense with the study and control glasses. Both glasses (study and control glasses) were tested for two weeks each. After the two weeks test, each of the glasses was evaluated. For evaluation a visual analogue scale questionnaire (Scale 0 - 100) was used. Question: How would you evaluate driving safety sense when driving in twilight or night with the tested glasses? Answer: visual analogue scale slider from 0 (not safe) to 100 (very safe)

Inclusion Criteria: Visual Acuity at least 0.8 (5/6) Binocular Vision Exclusion Criteria: refraction more than sph +/- 6 D and cyl 2 D Difference between habitual correction and actual refraction more than 0.5 D Medication with an influence on visual system Disease or eye disease with an effect on the visual system pregnancy or other hormonal variances influence of drugs mental handicap