Restoration of Vision After Brain Injury Using Magnet Glasses

Abstract

Visual impairments are common after traumatic brain injury (TBI) and negatively affect quality of life. We describe a 39-year-old woman with a severe TBI who was evaluated by the inpatient optometry and vision rehabilitation service with findings of complete right homonymous hemianopia and right cranial nerve III palsy with 30-degree right exotropia (eye turn out) and complete right ptosis (eyelid will not open). The 30-degree exotropia advantageously generated 30 degrees of right visual field expansion when the right ptosis was treated with a magnetic levator prosthesis, which restores eyelid opening. Once opened, the patient used visual field expansion derived from a right exotropia to overcome functional impairments caused by right hemianopia. Field expansion improved the patient's wheelchair mobility and reaching tasks during inpatient therapy. This is the first report of visual field expansion by strabismus facilitated by correction of ptosis. Strabismus should be considered for its potential field expansion benefits when homonymous visual deficits are present, before considering patching. A multidisciplinary vision rehabilitation team is well suited to make this determination.

Figure 1

A: Schematic of right hemianopia when fixating an object 2m distant (cross) and B: field expansion that occurs from right exotropia of 30°. The hashed red and blue lines represent the intact left visual fields. The areas of hemianopic vision loss are shaded gray. Field expansion comes at a cost- overlapping and double images in the portions of the field where red and blue fields overlap. Patients may or may not be bothered by double vision depending on the location of the object of interest, the type of task, and the degree of eye turn. As the magnitude of the eye turn increases, the secondary double image from the deviated eye is shifted further peripherally where it causes less interference. Therefore patients with larger angles of strabismus have more field expansion and are less likely to be bothered by the side effects of the strabismus.

Figure 2

a) Video frame showing complete ptosis of the right eye from CN III palsy. b) When wearing the MLP the right eye can be voluntarily opened and closed. The patient is looking at the camera with the left eye, but direction of gaze of the right eye is approximately 30° rightward due to the CN III palsy/exotropia. c) Illustration of the optometrist drawing from the inpatient record with angular estimates for c) left eye only and d) with the right lid opened with the MLP to reveal the exotropia and field expansion. The dark areas on the plot are unseen, white areas are seen. Confrontations results were identical at the 5-day follow-up.

Figure 2

a) Video frame showing complete ptosis of the right eye from CN III palsy. b) When wearing the MLP the right eye can be voluntarily opened and closed. The patient is looking at the camera with the left eye, but direction of gaze of the right eye is approximately 30° rightward due to the CN III palsy/exotropia. c) Illustration of the optometrist drawing from the inpatient record with angular estimates for c) left eye only and d) with the right lid opened with the MLP to reveal the exotropia and field expansion. The dark areas on the plot are unseen, white areas are seen. Confrontations results were identical at the 5-day follow-up.

Figure 3

Goldmann perimetry plots performed 2 months after discharge from the rehab hospital by a technician masked to the expected result. Right visual field expansion out to 30° was measured under binocular conditions (right-most panel), compared to either eye independently (middle and left). Note that the field plots are from the patient’s perspective, whereas the video frames in 2a & 2b are from the clinician’s perspective. Dashed lines represent a normal field extent in people without hemianopia. The right eye had some reduced visual field on the left side as well, related to traumatic optic neuropathy.