TY - JOUR
T1 - Objective measurement of forward-scattered light in the human eye: An electrophysiological approach
AU - Solf, Benjamin
AU - Schramm, Stefan
AU - Link, Dietmar
AU - Klee, Sascha
AU - Merigan, William H.
N1 - Publisher Copyright:
© 2019 Solf et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
PY - 2019/4/4
Y1 - 2019/4/4
N2 - Purpose Psychophysical measurements are used to examine the perception of ocular stray light, for example, with C-Quant. These measurements are subjective due to their principles. This work aims to determine ocular stray light objectively; thus, a psychophysical method is transferred into an electrophysiological setup. Methods Stray light perception was measured using steady-state visual evoked potentials (VEPs) in 10 healthy subjects (7 males, 3 females, mean age ± SD: 29.6 ± 4.1 years). Stray light emulating filters (Tiffen Black Pro Mist 2) were used for simulating the effect of cataracts to validate the results for increased scattered light conditions. Based on the direct compensation method, the stimulus consisted of a central test field (radius = 2) with a luminance adjustable compensation light and surrounding ring-shaped stray light source (radius = 5 to 10). Both flickered in the counter phase at a frequency of 7.5 Hz. The stimuli were presented for 15 luminance levels of the compensation light. The recorded steady-state VEPs at Oz channel were transformed by means of Fourier analysis. The magnitudes at the evoked frequency were plotted against the measured brightness levels of the compensation light. By fitting two linear functions to the resulting data points, a robust minimum log(Leq) was determined, which was correlated with the amount of stray light perception. We measured the stray light parameter log(sc) using C-Quant. For comparison, our results were converted into the C-Quant equivalent parameter log(sepm) and paired t-tests were performed for normal distributed results. Results A significant difference is observed between log(sepm) (without filter) and log(sepm) (with BPM 2 Filter) (p>0.05). No significant difference is observed between log(sepm) (without filter) and log(sc) (without filter) (p > 0.05) and between log(sepm) (with BPM 2 filter) and log (sc) (with BPM 2 filter) (p > 0.05). Conclusion The electrophysiological approach offers the ability to measure stray light perception in an objective manner.
AB - Purpose Psychophysical measurements are used to examine the perception of ocular stray light, for example, with C-Quant. These measurements are subjective due to their principles. This work aims to determine ocular stray light objectively; thus, a psychophysical method is transferred into an electrophysiological setup. Methods Stray light perception was measured using steady-state visual evoked potentials (VEPs) in 10 healthy subjects (7 males, 3 females, mean age ± SD: 29.6 ± 4.1 years). Stray light emulating filters (Tiffen Black Pro Mist 2) were used for simulating the effect of cataracts to validate the results for increased scattered light conditions. Based on the direct compensation method, the stimulus consisted of a central test field (radius = 2) with a luminance adjustable compensation light and surrounding ring-shaped stray light source (radius = 5 to 10). Both flickered in the counter phase at a frequency of 7.5 Hz. The stimuli were presented for 15 luminance levels of the compensation light. The recorded steady-state VEPs at Oz channel were transformed by means of Fourier analysis. The magnitudes at the evoked frequency were plotted against the measured brightness levels of the compensation light. By fitting two linear functions to the resulting data points, a robust minimum log(Leq) was determined, which was correlated with the amount of stray light perception. We measured the stray light parameter log(sc) using C-Quant. For comparison, our results were converted into the C-Quant equivalent parameter log(sepm) and paired t-tests were performed for normal distributed results. Results A significant difference is observed between log(sepm) (without filter) and log(sepm) (with BPM 2 Filter) (p>0.05). No significant difference is observed between log(sepm) (without filter) and log(sc) (without filter) (p > 0.05) and between log(sepm) (with BPM 2 filter) and log (sc) (with BPM 2 filter) (p > 0.05). Conclusion The electrophysiological approach offers the ability to measure stray light perception in an objective manner.
UR - http://www.scopus.com/inward/record.url?scp=85063986602&partnerID=8YFLogxK
U2 - 10.1371/journal.pone.0214850
DO - 10.1371/journal.pone.0214850
M3 - Journal article
SN - 1932-6203
VL - 14
SP - e0214850
JO - PLoS ONE
JF - PLoS ONE
IS - 4
M1 - e0214850
ER -