Abstract
Purpose :
Accommodation dysfunction following mild traumatic brain injury (mTBI) can lead to symptoms such as blur, asthenopia, and photosensitivity, impairing patients’ near-work comfort and efficiency. Accommodative insufficiency is widely reported in mTBI patients who show significantly higher accommodative error (AE). Chromatic filters (CF) have been used as a clinical treatment to improve these symptoms. This study aimed to explore the potential mechanism underneath the CF treatment effect by assessing the effective threshold to blur (ET), a concept introduced by Jiang's modified control model for steady-state accommodation to account for the sensory component.
Methods :
Data was obtained from 54 healthy (age 21-30 years) and 30 mTBI subjects (age 18-33 years) using Power Refractor 3. Monocular static accommodation was recorded continuously for 1 minute at 5 distances (6m-20 cm) under 3 conditions: baseline without filter (NF), subjects' selected CF using the Intuitive Colorimeter, and transmission-matched neutral density filters (ND). Further subgrouping was based on subjects’ high vs. low color preference. ET was averaged for all distances. The longitudinal chromatic aberration (LCA) was calculated for each selected CF.
Results :
Consistent with previous report, AE significantly correlated with ET for non-TBI subjects for all conditions. This correlation was disrupted in the mTBI group and restored by CF and ND Fig.1. The non-TBI group did not show any correlation between ET and LCA Fig.2. Similar result was found in mTBI subjects with low color preference. In contrast, the mTBI subjects with high preference selected a wavelength that induced ET change which was highly correlated with the LCA (r=-0.90, p=0.001), indicating a potential link between the color and accommodative sensory control.
Conclusions :
Our data suggested that accommodation sensory control was impaired in mTBI patients. CF and NF rescued this impairment by altering wavelength and/or luminance. Subjects with high color preference selected color that might modify the ET via LCA, restoring the control through blur sensitivity. This finding provided the first evidence supporting the hypothesis that the CF treatment effect in mTBI might rely upon improving accommodation control.
This is a 2021 ARVO Annual Meeting abstract.