Commotio Retinae is a transient opacification of the retina due to outer retinal disruption occurring in a contre-coup fashion after blunt trauma injury.^1,2 Histological studies in animals and humans after ocular blunt trauma have revealed that disruption occurs at the level of the photoreceptor outer segments and retinal pigment epithelium (RPE).^2,3 Recent reports using optical coherence tomography (OCT) have shown detectable disruption at the level of photoreceptor inner segment/outer segment junction and RPE ^4-6 and that these changes may be reversible overtime with restoration of normal outer retinal architecture.⁵ However, resolution of existing OCT technology may not be sensitive enough to detect photoreceptor disruption. Adaptive optics (AO) imaging systems enable cellular-resolution imaging of the human retina, and there is a growing number of cases where deficits have been visible on AO images but not on OCT. Here we present a case of subclinical photoreceptor disruption after head trauma as seen by adaptive optics scanning ophthalmoloscope (AOSO) not apparent clinically or on spectral domain-OCT.

A 43-year-old male described a 5-year history of a stable, crescent-shaped purple scotoma nasal to central fixation in his right eye that developed after an industrial accident in which he sustained significant head and body trauma. A complete ophthalmic examination revealed best-corrected vision of 20/20 OU and no fundus findings or abnormalities. Fluorescein angiogram (FA) and spectral domain optical coherence tomography (SD-OCT) (Spectralis SD-OCT, Heidelberg Engineering, Carlsbad, CA) were unremarkable. (Figure 1) Humphrey Visual Field 10-2 testing and microperimetry revealed a small nonspecific area of functional visual loss near fixation in the right eye. Images of the photoreceptor mosaic near the fovea were acquired using a newly developed AOSO. Images were processed and registered using custom MatLab software (The Math works, Natwick, MA). While foveal cone density was normal, the AOSO images revealed a well-defined crescent-shaped area of photoreceptor disruption just temporal to the fovea. (Figure 2A – large arrows) Other focal areas of photoreceptor irregularities were also seen superior, temporal and inferior temporal to the fovea. (Figure 2A- small arrows) Both cone and rod photoreceptors were visualized with this AOSO imaging, and both cell types appear to be disrupted. (Figure 2 A, B)

AOSO detected photoreceptor disruption resulting from head trauma not apparent clinically or by other standard imaging modalities, including SD-OCT. Restoration of outer retinal appearance in SD-OCT has been reported after commotio retinae⁵, suggesting recovery of outer retinal structure. Our data demonstrate photoreceptor disruption may still exist. SD-OCT axial resolution is likely not sensitive enough to reveal the full extent of photoreceptor disruption that may occur after ocular or head trauma. AOSO imaging may prove useful in improved detection and understanding of photoreceptor involvement in ocular or head trauma. In addition, patients with traumatic brain injury often report visual symptoms. AOSO may be of value to help differentiate retinal versus cortical contributions to vision loss in these patients.