Authors
Yuhas, Phillip T.; Shorter, Patrick D.; McDaniel, Catherine E.; Earley, Michael J.; Hartwick, Andrew T. E.

Blue and Red Light-Evoked Pupil Responses in Photophobic Subjects with TBI

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Abstract/Introduction

Purpose 

Photophobia is a common symptom in individuals suffering from traumatic brain injury (TBI). Recent evidence has implicated blue light-sensitive intrinsically photosensitive retinal ganglion cells (ipRGCs) in contributing to the neural circuitry mediating photophobia in migraine sufferers. The goal of this work is to test the hypothesis that ipRGC function is altered in TBI patients with photophobia by assessing pupillary responses to blue and red light.

Methods 

Twenty-four case participants (mean age 43.3; 58% female), with mild TBI and self-reported photophobia, and 12 control participants (mean age 42.6; 58% female) were in this study. After 10 minutes of dark adaptation, blue (470 nm, 1 × 1013 phots/s/cm2) and red (625 nm, 7 × 1013 phots/s/cm2) flashing (0.1 Hz) light stimuli were delivered for 30 seconds to the dilated left eye while the right pupil was recorded. The amplitude of normalized pupil fluctuation (constriction and dilation) was quantified using Fourier fast transforms.


Conclusion/Results

Results 

In both case and control participants, the amplitude of pupil fluctuation was significantly less for the blue light stimuli as compared to the red light stimuli, consistent with a contribution of ipRGCs to these pupil responses. There was no significant difference in the mean pupil fluctuation amplitudes between the two participant groups, but case participants displayed greater variability in their pupil responses to the blue stimulus.

Conclusions 

Case and control participants showed robust ipRGC-mediated components in their pupil responses to blue light. The results did not support the hypothesis that ipRGCs are “hypersensitive” to light in TBI participants with photophobia. However, greater pupil response variability in the case subjects suggests that ipRGC function may be more heterogeneous in this group.


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Testimonials


My eight year old daughter was terrified to go to the eye doctor for fear of her eyes being dilated. The doctor was SO KID friendly! He immediately made her comfortable by engaging her in conversation. It was a geat experience.


Joya B.

Dr. Garbus spent an amazing amount of time to solve my very complicated visual problems. Over the years he has continually achieved results beyond what others felt possible. He is always up to date on the latest science. He is great!


Dolores K.

Family Vision Care Valencia makes it so easy. Staff is knows what they are doing and Dr. Garbus is thorough and kept me well informed during the exam.


Kristy B.

I have been coming to Family Vision Center for almost 20 years. Dr. Garbus has been able to help my vision when other doctors could not. Now my kids see him as well. I highly recommend this office!


Autumn C.

The Doctor is very good. I felt on this visit he seemed rushed. I had questions to ask him but he was already with another patient. I still do not know if my eyes are the same , worse, or better.


Howard B.

All the staff is friendly, helpful and knowledgeable, and has been for all the years I have been going there.


Mary Ann H.
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