Accommodation and stereopsis in adults with traumatic brain injury

Abstract

Background: Traumatic brain injury has many adverse effects on visual functions. The aim of this study is to evaluate accommodation, stereopsis deficits and visual symptoms in Chinese patients with traumatic brain injury. Methods: This is a cross-sectional study that included 22 patients with traumatic brain injury and 22 controls; the refractive status, stereoacuity, and accommodative ability of each subject were measured. Results: Patients with traumatic brain injury were significantly more symptomatic than controls (p < 0.001). Near stereoacuity thresholds were significantly elevated in patients with traumatic brain injury compared to controls (p < 0.001). Accommodative amplitude (right eye: p = 0.007; left eye: p = 0.01; both eyes: p = 0.002) and accommodative facility rates (right eye: p < 0.001; left eye: p < 0.001; both eyes: p < 0.001) were significantly lower in patients with traumatic brain injury, for whom there were no significant differences between the accommodative facility rates of the pre-and post-three-minute binocular flipper sessions (p = 0.51). Patients with traumatic brain injury showed greater accommodative lag to 2.5 D (p = 0.03), 3 D (p = 0.03), 4 D (p = 0.004) and 5 D (p = 0.001) stimuli, but not to the 2 D (p = 0.10) stimulus. The regression equation of accommodative lag to stimuli was steeper for the traumatic brain injury group (slope: p = 0.01; y-intercept: p < 0.0001). There were also significant correlations between visual symptoms and clinical findings including binocular accommodative amplitude (r = −0.480, p = 0.001), binocular accommodative facility (r = −0.445, p = 0.004) and stereopsis (r = 0.457, p = 0.002). Conclusion: Patients with traumatic brain injury have deficits in accommodation and stereopsis.

Montreal Brain Injury Vision Screening Test for General Practitioners

“…Q 2. Another core visual complaint post-TBI has to do with accommodative insufficiency (Ciuffreda et al, 2007 ; Chen et al, 2020 ), i.e., the inability of the visual system to accommodate on a visual target ( Figure 4 ). While accommodation is engaged every time we focus on a target, its function can mostly be tested when reading.…”

“…An accommodative insufficiency is tested by assessing the patient's capacity to focus and read using a near vision reading chart at 40 cm. Post-TBI, a clinician can expect reading difficulties during this test (Chen et al, 2020 ), and the difficulty can be alleviated by use of a positive lens—typically varying from +1 to +2.00 that can be added while the patient is reading ( Figure 4C ). To dissociate with possible presbyopia, physicians should verify that the blurred perception during reading began after the head injury.…”

“…An accommodative insufficiency is tested by assessing the patient's capacity to focus and read using a near vision reading chart at 40 cm. Post-TBI, a clinician can expect reading difficulties during this test (Chen et al, 2020), and In the presence of an accommodative insufficiency, the patient is unable to focus on the target and sees the reading blurry (B). In such a case, the addition of a positive lens (+1.00 to +2.00) should bring the target within the patient's range of accommodation which should bring the target in focus (C).…”