Abstract
Purpose :
Mild traumatic brain injury (mTBI) is associated with visual symptoms including binocular vision problems, eye strain, photophobia, headaches and blurred vision. There are indications that the nerve fiber layer may be compromised in such patients. This study investigated the inner and outer retina using a combined adaptive optics (AO) – optical coherence tomography (OCT) – scanning laser ophthalmoscopy (SLO) system that allows simultaneous enface and cross-sectional viewing of the retina.
Methods :
Two patients diagnosed with mTBI for several years (2 years for mTBI #1 and 3 years for mTBI #2) underwent retinal imaging and functional testing. Both patients complained of binocular vision problems; convergence excess and accommodative infacility for mTBI #1 and fusional vergence dysfunction and accommodative insufficiency for mTBI #2 with severe photophobia. Retinas were imaged with a fundus camera, spectral-domain OCT and the AO-OCT-SLO system. Humphrey 24-2 SITA-FAST threshold tests measured visual sensitivity over the central 50°. AO images were taken at 8° temporal retina (TR), fovea and 4° and 8° nasal retina (NR). Cone spacing, total retinal thickness (TRT), inner retinal thickness (IRT), inner segment (IS) and outer segment (OS) lengths and nerve fiber bundle (NFB) diameters were measured. Both eyes of mTBI subjects were tested and the results compared to age-matched control subjects.
Results :
Both eyes of mTBI patients showed normal visual field results. TRT was thicker in control subjects than in mTBI patients at 8° TR, fovea and 4° NR (p < 0.05). For the IRT, the trend was not as consistent; at 8° TR, the IRT was thicker in control subjects (p <0.05) but at 4° NR, mTBI #1 had significantly thinner IRT whereas mTBI #2 had significantly thicker IRT than the controls, with correspondingly larger NFB diameters. Overall, mTBI #1 had shorter IS and OS lengths compared to both the controls and mTBI#2. Significantly larger cone spacing was found in mTBI patients than in control subjects (p < 0.05) at 4° NR, but at other retinal locations, the difference in cone spacing was not statistically significant. NFB diameter directly correlated with the thickness of IRT.
Conclusions :
There were no consistent trends in changes of inner and outer retina in two chronic mTBI patients with binocular vision problems compared to age-matched control subjects, further study with more subjects is warranted.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.