Abstract
Purpose :
Accommodation dysfunction following mild Traumatic Brain Injury (mTBI) can cause symptoms such as diplopia, blurry vision, headache and asthenopia that impact near-work tasks. Chromatic filters have been shown to impact accommodative function and reading behavior. They are also used clinically in treating patients with mTBI and subsequent light sensitivity. However, they have not been investigated for their effect on the accommodation system in the mTBI population. This study aimed to assess the accommodation function in subjects with mTBI, and the effect of chromatic filters on their accommodative response.
Methods :
Totally, 28 healthy subjects and 19 with mTBI (age 18-33) were recruited. Three testing conditions were used: baseline without filter, subjects' selected chromatic filter that provides the most comfort and text clarity using the Intuitive Colorimeter, and luminance-matched neutral density filters. Power Refractor 3 was used to assess the accommodation response monocularly from the right eye. After 5 minutes dark adaptation, static accommodation was recorded continuously for 1 minute while subjects viewed high contrast target at 5 distances respectively (6m-20 cm in randomized order).
Results :
Except at distance, mTBI subjects showed significant accommodative lag at all targets demand levels, rendering a significantly lower k value for the fitted stimulus-response curve (Fig. 1) (groups mean difference for k = -0.35, p < 0.01). Lens conditions did not show an effect on k value within the mTBI group. However, k was different between neutral density filter and chromatic or no lens conditions within the non-TBI group (mean difference 0.1, p = 0.03 and 0.091, p = 0.01, respectively) (Fig. 2).
Conclusions :
To our knowledge, this is the first study to objectively investigate the effect of filters on accommodation response in individuals with mTBI. Our results showed impaired accommodative response in mTBI subjects during the static accommodation task. However, filter conditions have no significant impact on the stimulus-response relationship. It is possible that the effect of filters might be on the dynamics of accommodation/disaccommodation, or the stability and microfluctuation status. Further studies are warranted to investigate the mechanism of how chromatic filters work in individuals with mTBI.
This is a 2020 ARVO Annual Meeting abstract.