Abstract
Purpose :
Myopia control lenses that use optical scattering are associated with deteriorated retinal image quality. Little is known about visual processing in this context. Therefore, this study investigated the impact of short-term neural adaptation on induced optical scattering.
Methods :
Neural adaptation was determined by changes in the neural contrast sensitivity, which was psychophysically measured with a unique interferometric system enabling an aberration-free stimulus presentation. A 1.5-degree narrowband (550 ± 5 nm, 300 td) stimulus was used containing horizontal fringes with a spatial frequency of 6 cycles per degree. Neural contrast sensitivity is reported in logarithmic scale units (logCS) as the average of four consecutively recorded threshold measurements via method of adjustment. The retinal image was optically degraded by two separately tested conditions: 0.8 Bangerter foil and spherical defocus of +0.5 D. Each reduced the visual acuity equally by one line on the letter vision chart. In a control condition the participants were tested with a clear lens.
Measurements were carried out with the respective dominant eye of 30 participants (22 females, spherical equivalent of -1.00 ± 1.82 D) before and after an adaptation period of 30 min. During adaptation participants watched a movie in 5 m distance. Mean differences and standard error of neural contrast sensitivity were reported and analyzed by t-tests.
Results :
Neural contrast sensitivity improved after adaptation for all conditions: +0.05 ± 0.01 logCS for Bangerter foil (p < 0.001), +0.02 ± 0.02 logCS for defocus (p = 0.32), and +0.03 ± 0.01 logCS for control (p = 0.01). Only the adaptation to the Bangerter foil condition showed significantly increased changes compared to the defocus condition (p = 0.01) and the control condition (p = 0.02).
Conclusions :
Although both conditions reduce the visual acuity by one line on the letter vision chart, the Bangerter foil affects contrast across all spatial frequencies, while defocus impacts mainly higher spatial frequencies. Consequently, short-term neural adaptation was only observed in the Bangerter foil condition. In summary, this study contributes to understanding the neural mechanisms triggered by optical scattering of myopia control lenses.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.