Indirect Traumatic Optic Neuropathy in Mild Chronic Traumatic Brain Injury

Abstract

PURPOSE. To analyze the clinical presentation and optical coherence tomography (OCT) findings in indirect traumatic optic neuropathy (ITON) in veterans with chronic mild traumatic brain injury (mTBI). METHODS. This retrospective study is the first to describe the OCT pattern of subclinical to mild ITON in veterans with chronic mTBI. The thicknesses of the macular ganglion cell layer (mGCL), peripapillary retinal nerve fiber layer (pRNFL), and subfoveal choroidal layer were analyzed in young veterans who had mTBI of >6 months' duration and either blunt head injury or improvised explosive device (IED) concussions. RESULTS. Three major OCT findings were demonstrated: (1) temporal pRNFL thinning was associated with subclinical TON in the eyes of chronic mTBI patients compared with controls; within mTBI subjects, nasal mGCL thinning at the 3-mm modified Early Treatment Diabetic Retinopathy Study circle diameter distance from the fovea correlated with the corresponding temporal retinal nerve fiber layer thinning; (2) inner (1 mm) superior thinning was greater than that of the temporal mGCL in blunt head injury and could potentially distinguish it from IED concussive head trauma; and (3) subfoveal choroidal thinning was significantly worse in eyes of mTBI patients compared with those of controls. CONCLUSIONS. These OCT findings may contribute to the understanding of the spectrum of visual injuries resulting from head trauma.

Indirect traumatic optic neuropathy after head trauma in adolescent male mice is associated with behavioral visual impairment, neurodegeneration, and elevated endoplasmic reticulum stress markers at acute and subacute times

“…Further, many symptoms may not be identified immediately, which can lead to missed diagnosis, especially in connection to the head injury. [2] Visual sequelae of TBI can also cause significant issues with recovery, [3] and can impact functional outcomes in children after even mild injuries. [4] Among the pathophysiologic mechanisms of TBI-associated visual deficits is traumatic optic neuropathy (TON).…”

“…[8] Optical coherence tomography (OCT) can also be a useful tool as it has revealed that indirect TON (iTON) results in significant thinning and deterioration of retinal layers at the time of injury and up to 35 years later, with retinal ganglion cell (RGC) death seemingly initiating subsequent deterioration of the other retinal layers. [2] Imaging of iTON within the brains of living human subjects, on the other hand, has only been possible through diffusion tensor imaging (DTI), thus limiting our knowledge of iTON. DTI has suggested that mild TBI can produce axonal injury in optic radiations [8][9][10] and the anterior thalamic radiations from the lateral geniculate body [9].…”

Acute monocular nasal hemianopia following a mild traumatic brain injury

“…Chan et al analyzed 19 veterans who suffered from indirect TON in mild chronic traumatic brain injury. [ 10 ] They found 3 major patterns of optical coherence tomography changes in these patients:…”

“…Mild traumatic brain injury is defined as traumatic head injury with conscious loss less than 30 minutes, a Glasgow coma scale score of 13 or more, and amnesia less than 24 hours. [ 10 ] In some uncomplicated brain concussion cases, computed tomography scans or MRI may not detect brain structural damage. However, clinicians should keep in mind that limited structural axonal injury and permanent loss of axonal function might be present without radio-image evidence.…”

Association of Optical Coherence Tomography With Longitudinal Neurodegeneration in Veterans With Chronic Mild Traumatic Brain Injury

“…11,12 The association of OCT measures of retinal layer thinning with the degree of central nervous system (CNS) neurodegeneration has been well-established in disorders such as Alzheimer disease, Parkinson disease, and multiple sclerosis. [13][14][15][16][17][18][19][20] OCT has been used to detect neurodegeneration in preclinical models of TBI [21][22][23] and in a few human studies, [24][25][26][27][28] but longitudinal studies have been lacking. The current study aimed to identify evidence of neurodegeneration through longitudinal evaluation of structural and functional changes in the visual nervous system and CNS in veterans with a history of mild TBI.…”