Many people develop intolerance to light after a head injury, leading to ambient light levels causing discomfort. We do not fully understand why this occurs and how it should be treated. A growing number of clinicians have reported improvement in TBI related symptoms reported by patients that undergo daily fixation training with a dim light target. While fixation training using various colored light targets is reported, blue light targets specifically appear to be used in this patient population more often than other light target colors. However, the effectiveness of this approach has yet to be assessed in a well-controlled clinical study. In this work, we will recruit individuals who had a recent brain injury and developed increased light sensitivity. Participants will be divided into two groups: one that first uses daily 20 minute sessions for 12 weeks with the at-home fixation device set to display a blue light target; and another that will undergo similar sessions for 12 weeks using a red light target. Every 6 weeks, masked examiners will measure how well participants can read letters on an eye chart, record pupil responses to light, measure the side vision, measure eye alignment and focusing ability when viewing a near target, and collect information about participants' symptoms. In a cross-over study design, the participants will then switch to sessions involving the other colored fixation light target for another 12 weeks, with data being again collected every 6 weeks. Potential differences in pupil responses to light between the treatment groups will be assessed as an objective outcome measure and compared to subjective symptom survey information. Thus, this work will test the hypothesis that daily fixation training using a blue light target can alleviate light intolerance in participants after head injury more than fixation training with a red light target, and this improvement is associated with altered pupil responses to light. As a significant minority of eye care clinicians currently utilize this approach in this population of patients, this study has the potential to influence clinical practice patterns whether the fixation training is shown to be effective or not.

A growing number of clinicians are regularly using fixation training, in which patients undergo daily sessions fixating on colored light targets on light boxes, to treat symptoms including photophobia associated with traumatic brain injury (TBI). While fixation training using various colored light targets is reported, blue light targets specifically appear to be used in this patient population more often than other light target colors. The College of Syntonic Optometry (www.csovision.org) estimates that there are roughly 500 practicing optometrists that utilize fixation training in the USA alone. However, evidence supporting this approach is primarily anecdotal, and there are no controlled, masked clinical trials published that evaluate the efficacy of this therapy against a control group.

Therefore, the goal of this study is to assess whether daily 20 min fixation training sessions using a blue light target alleviates symptoms of light sensitivity and alters pupil response more than daily 20 min fixation training sessions using red light targets in a masked cross-over clinical trial involving participants with chronic TBI-associated photophobia. In addition, we will determine if any improvement in symptomology correlates to any changes in pupil responses to red, blue and white light pulses and potential changes in other standard clinical measures of visual function. In short, this study will compare the effect of fixation training using a blue light target to the effect of fixation training using a red light target in participants with chronic TBI-associated photophobia.

Inclusion Criteria:

• 18 to 80 years old and subjects able to consent for themselves
• Completion of first session in entirety (participants who cannot complete the entire first visit will be considered as a screen fail)
• Best-corrected visual acuity of at least 20/32 in both the right and left eyes, and 20/25 using both eyes
• Prior head injury with current photophobia - A mild or moderate TBI occurring at least 3 months prior to visit, verified by a score of 2, 3 or 4 on OSU-TBI survey, and participant reports having experienced greater light sensitivity since their head injury

Exclusion Criteria:

• Pregnancy or suspected pregnancy - based on self-report
• Previous history of neurodegenerative disease (e.g. Alzheimer's, Parkinson's, multiple sclerosis, myasthenia gravis, seizures)
• History of pathology of the retina and optic nerve (includes retinal tears, diabetic retinopathy, glaucoma, macular degeneration, optic nerve atrophy)
• Currently on cholinergic medications, which affect pupil responses
• Prior participation in fixation training sessions within the past 2 years
• Experiencing a migraine during visit
• Prior history of severe TBI (score of 5 or 6 on OSU-TBI survey)