Commotio retinae refers to traumatic retinopathy secondary to direct or indirect trauma to the globe. Retinopathy may be present at areas of scleral impact (coup) and or distant sites (contrecoup) including the macula. Commotio retinae in the posterior pole is also referred to as Berlin's edema.
Closed globe trauma or blast injury. Commotio retinae is present in about 30% of all eye traumas presenting for hospital treatment.
High impact sports activities (most commonly ball sports), violence, motor vehicle accidents and other activities associated with blunt trauma to the face and orbits.
Blunt trauma causes displacement of the lens-iris diaphragm with expansion of peripheral structures outward. Indirect injuries such as blast trauma or orbital trauma transmit shockwaves to the globe causing similar deformation related force injuries. This causes stretching and tearing of ocular tissues secondary to vitreoretinal deformation caused by transmission of hydraulic forces.  The retina is inelastic and absorbs the full effect of shock waves resulting in injury to various layers mainly the outer segment of photoreceptor and RPE junction. It has been postulated that the injury is most severe at the photoreceptor processes as they are not suspended by the Muller cells, in contrast to the remainder of the neurosensory retina.
There is no significant blood retina barrier breakdown associated with commotio retinae. The retinal blood flow does not appear to be altered, though the choroidal circulation may be impaired.
Mansour et al. showed disruption of photoreceptor outer segments, deposition of debris in the subretinal space and RPE cell injury in a cadaveric human eye processed within 24 hours of trauma. The characteristic glistening appearance described below is likely related to increased scattering of light by the abnormal photoreceptor processes and subretinal debris, which is well characterized by OCT.
Restoration of photoreceptor outer segments begins at 1 week and continues for at least 2 months which may explain course of visual acuity recovery. The clinical appearance of commotio retinae resolves within 1 week, with restoration of normal fundus appearance or pigmentary changes depending on the severity of the injury.
Primary prevention includes protective eye wear for athletes. 2-mm polycarbonate lenses in normal streetwear is recommended for low impact sports. Impact resistant sports frames with a 3-mm polycarbonate lens are recommended for moderate to high impact sports. Face masks attached to a helmet should be used in the highest risk sports including ice and field hockey, football, baseball, and lacrosse.
Diagnosis is clinical and is made based on characteristic appearance listed below Physical Examination. OCT usually shows hyper-reflectivity of the ellipsoid layer. 
Patients or bystanders will often offer a mechanism of trauma. It is important to screen for child abuse and domestic abuse as indicated.
A complete ophthalmoscopic exam to rule out open globe injury and orbital fracture including dilated fundus examination is indicated after significant trauma.
Dilated funduscopic exam reveals glistening gray-white opacification of the neurosensory retina with or without intraretinal hemorrhages and RPE mottling. A pseudo cherry red spot may be seen when commotio involves the fovea. The fundus reflex may be notably white as opposed to red.
Optical coherence tomography (OCT) signs include increased reflectivity and thickness of ellipsoid zone (EZ) with disruption of interdigitation zone (IZ) and occasionally inner retinal layers.
OCTA may or may not show any significant microvascular changes in the superficial or deep capillary plexuses.  Montorio et al reported OCTA findings over 6 months of 18 patients with Berlin's edema after blunt trauma; an initial early decrease in vessel density in superficial and deep capillary plexuses along with radial peripapillary capillary plexus was seen at 1 month with gradual normalizing of the values at 6 months. 
Blurry vision, vision loss or visual field defect occurs immediately following trauma.
- Dilated fundus examination
- Fundus photography
- Ultrasonography in cases with unclear media due to vitreous hemorrhage or anterior segment injury.
- Retinal ischemia
- Choroidal rupture
- Purtscher retinopathy
- Traumatic macular hole
- Chorioretinitis sclopetaria
- Retinal detachment
Patients suffering substantial ocular trauma with commotio retinae should be followed with serial eye exams to evaluate for any additional treatable conditions. As commotio of macula resolves, partial or full thickness macular holes can develop.
There is no approved or commonly used medical treatment for commotio retinae. However, in cases that do not resolve spontaneously, high dose IV steroids have been anecdotally shown to reduce retinal swelling and improve visual acuity. 
Acute commotio retinae is commonly associated with traumatic macular hole, retinal tears, choroidal rupture, lens subluxation, hyphema, orbital fractures, late glaucoma, late cataract, late retinal tears, widespread chorioretinal atrophy.
While most patients recover completely, some patients will remain visually impaired with reduced vision or paracentral scotoma.
Ahn et al. created a 4-step grading system for prognosis by evaluating damage in photoreceptor layers including cone outer segment, inner segment and external limiting membrane. The classification is based on OCT findings: Grade 1: increased reflectivity of the EZ with loss of ordinary definition of the photoreceptor lines. Grade 2: loss of reflection in cone outer segment tips (IZ) Grade 3: loss of reflection in IZ and EZ Grade 4: loss of reflection in the IZ, EZ and ELM. In this study increasing grades of pathology were predictors of poor visual recovery.
Most cases resolve within 4 weeks of injury although some improvement can continue for up to 6 months. However, some patients can have permanent macular damage with absolute or relative scotoma. Patients with commotio retinae involving macula have poorer prognosis because of damage to the fovea along with increased risk of macular hole or permanent RPE atrophy as a secondary complication. 26% of patients with macular involvement are permanently visually impaired with a VA of <20/30. This is in comparison with 3% of patients sustaining permanent visual consequences after extramacular injury. There are no treatments to improve outcomes in these patients.
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