a 68-year - old male presented complaining of sudden and profound loss of central vision in his left eye following blunt eye trauma .
he reported seeing a large , dense , central scotoma that began fading 1 h after the injury .
he was emmetropic , phakic , and had no significant ophthalmic history . on examination , 24-h postinjury , best - corrected visual acuity ( bcva ) in the left eye
oct of the left macula ( spectralis , heidelberg engineering , 5-line raster acquisition protocol ) revealed abnormal hyper - reflectivity and nodularity of the photoreceptor os layer .
interestingly , the patient was found to have prominent abnormalities on infrared imaging using the infrared reflectance protocol of the spectralis oct [ fig . 1 ] .
infrared imaging of the left fundus revealed diffuse infrared hypo - reflectance dotted with spots of very low pixel value ( dark ) , creating a stippled appearance .
point - to - point correlation between the infrared and oct images using the spectralis software ( heidelberg engineering , germany ) demonstrated that the infrared dark spots correlated with foci of thickened os seen on 5-line raster oct .
no pathology of the superficial retina , retinal pigment epithelium or choroid was detected using red - free reflectance , fundus auto - fluorescence , and enhanced - depth imaging ( edi ) , respectively .
30 posttrauma , and at 8 months posttrauma , bcva in the left eye was 20/25 and the retina appeared normal on examination and when imaged with infrared reflectance , 5-line raster oct , fundus auto - fluorescence , and edi [ fig .
2 ] . left fundus images at day 1 postblunt trauma to the left eye .
( b ) infrared confocal scanning laser ophthalmoscope fundus image demonstrating stippled hypo - reflectance at the macula . ( c )
optical coherence tomography of the macula demonstrating abnormal hyper - reflectivity of the outer segments ( between arrowheads ) .
( b ) infrared confocal scanning laser ophthalmoscope fundus image reveals resolution of the infrared hypo - reflectance
in this case , there is a clear temporal relationship between eye trauma , transient vision loss , transient oct changes consistent with cr , and transient infrared hypo - reflectance .
cases of cr detectable on oct , but not fundus examination have been described , confirming that some cases of cr are subclinical . to the best of the authors knowledge
the pathology of cr has been studied histologically and on oct , and comprises fragmentation of the photoreceptor os without injury to the inner retina .
as demonstrated by our case , this manifests on 5-line raster oct as abnormal hyper - reflectivity of the os layer .
this oct feature is subtle and is easily overlooked if the study is not carefully scrutinized .
our case implicates infrared imaging as a diagnostic adjunct for detecting subclinical cr . since focal dark spots on infrared imaging correlated with points of nodular os thickening in our case
, we infer that the infrared hypo - reflectance in cr is caused by increased absorption of infrared light by an abnormal os layer . with a wavelength of 820 nm ,
the infrared mode of the spectralis oct penetrates deeper into the retina than modalities using visible wavelengths of light .
it is , therefore , useful for detecting outer retinal pathology , such as that of cr .
the spectralis uses a confocal scanning laser ophthalmoscope ( cslo ) and records infrared reflectance without barrier filters . compared with conventional recording techniques
, cslo improves image resolution by using a higher emission of light energy and by reducing the capture of scattered light .
further studies are required to determine whether infrared hypo - reflectance is a consistent feature in all cases of cr , and whether this imaging modality has greater sensitivity for detecting subclinical cr than 5-line raster oct .
nevertheless , this case suggests that infrared imaging may have a role as a diagnostic adjunct for detecting subclinical cr .
we recommend that clinicians consider performing infrared imaging of the retina when managing a patient who presents with unexplained vision loss after blunt trauma and a normal - appearing fundus .
 commotio retinae ( cr ) is an outer retinal disorder following blunt trauma to the eye . 
 histologically it is characterized by disruption of the photoreceptor outer segments ( os ) , typically without injury to other retinal layers . 
 using spectral - domain optical coherence tomography ( oct ) the condition is visible as hyper - reflectivity of the os . 
 most cases of cr are associated with transient grey - white discoloration of the retina and are easily diagnosed clinically , but there have been reports of oct - confirmed cr without retinal discoloration . 
 it is likely that this subclinical variant of cr is under - recognized as the oct features of cr are subtle . 
 here , we report a case of oct - confirmed subclinical cr that demonstrated prominent infrared hypo - reflectance , using the infrared protocol of the spectralis oct , heidelberg engineering . 
 this case suggests that infrared reflectance may have a role in diagnosing cases of subclinical cr . 