Commotio Retinae

Transient retinal whitening (so called Berlin oedema) of the outer retina after blunt trauma, caused by the contre coup transmission of the force of impact through the vitreous and globe to the retina and retinal pigment epithelium. The injury is to photoreceptor outer segments and the retinal pigment epithelium, with disruption and swelling, rather than true extracellular oedema.

• Most commonly at the posterior pole (macular involvement) or in the peripheral retina opposite to the impact site (temporal after a nasal blow).
• Common after sports injuries (balls, fists), fireworks, airbag deployment, paintball and road accidents.
• Often coexists with hyphaema, angle recession, vitreous haemorrhage, choroidal rupture, retinal tears and optic neuropathy.
• Natural history: whitening appears within hours and resolves over 3 to 4 weeks. Visual outcome depends on macular involvement and pigment changes.

• Blurred vision or central visual loss (variable, from normal to 6/60), often delayed hours after trauma; peripheral cases are asymptomatic.
• Grey white cloudy retinal discolouration with a "cherry red" appearance of the fovea, absence of retinal haemorrhage in the whitened area (though haemorrhages may coexist), and normal retinal vessels.
• Central scotoma, metamorphopsia and reduced contrast sensitivity if the macula is involved.
• Late: pigment mottling, macular atrophy, macular hole formation (from retinal thinning or vitreous traction), and permanent visual loss in a minority (about 10 to 20 percent of macular cases).

• Dilated fundus examination with indirect ophthalmoscopy and scleral depression (to detect peripheral injury and retinal tears), slit lamp biomicroscopy with a fundus lens.
• Optical coherence tomography: hyper reflectivity of the outer retinal layers (ellipsoid zone and photoreceptor tips), disruption of the interdigitation zone, subsequent outer retinal thinning, and exclusion of macular hole or subretinal fluid.
• Fundus autofluorescence for retinal pigment epithelium damage; fluorescein angiography is usually normal or shows minor leakage.
• Visual acuity, Amsler grid, visual fields, and examination for other injuries (hyphaema, angle, lens, optic nerve).
• Follow up OCT at 2 to 4 weeks and at 3 months.

• No proven treatment; most cases recover spontaneously. Reassure the patient and give a clear follow up plan.
• Observe with serial acuity and OCT at 1 week, 4 weeks and 3 months.
• Corticosteroids (oral prednisolone 1 mg/kg for 1 to 2 weeks) are used by some for severe macular involvement but without proven benefit; avoid if head injury or infection concerns.
• Treat associated injuries: laser retinopexy or cryopexy for retinal tears or dialysis, surgery for retinal detachment or macular hole (vitrectomy with internal limiting membrane peeling and gas tamponade).
• Advise protective eyewear, and instruct patients to return urgently for flashes, floaters, field loss or worsened vision.
• Dilated examination at 1 to 2 weeks and 3 months to detect delayed retinal tears or detachment.
• Prognosis is good when the fovea is spared; outer retinal disruption on OCT predicts poor recovery.