Commotio Retinae

Key Points at a Glance

Highlights of this disease

• Commotio retinae is a reversible lesion in which the outer segments of photoreceptors are damaged after blunt ocular trauma, resulting in white retinal opacification.
• Also called Berlin edema (Berlin opacity), this term is used when the macula is involved.
• White opacification peaks 2–3 days after injury and usually resolves spontaneously within 1–2 weeks.
• No effective drug treatment exists; observation is the mainstay.
• In macular lesions, higher OCT grades are associated with worse visual prognosis. ¹⁾
• Differentiation from irreversible retinal contusion necrosis is important; dense white opacification with hemorrhage suggests necrosis.
• In ocular trauma, complications other than retinal injury (hyphema, lens dislocation, angle damage) must also be assessed.

1. What is Commotio Retinae?

Commotio retinae is a reversible lesion caused by blunt ocular trauma, leading to disruption and edema of photoreceptor outer segments and retinal pigment epithelium (RPE) cells. The main finding is white retinal opacification, which often resolves spontaneously.

When the macula is involved, it is characterized by a cherry-red spot-like appearance at the fovea surrounded by white opacification, and is also called Berlin edema (Berlin opacity). In contrast, irreversible damage is termed retinal contusion necrosis.

It is a relatively common condition, occurring in about 30% of closed globe injuries. It can result from direct impact (coup injury) or from shock waves transmitted to the opposite side (contrecoup injury).

Q Are "commotio retinae" and "Berlin edema" the same disease?

A

Berlin edema is the term used for commotio retinae occurring in the macula. It presents with a characteristic appearance: the fovea looks like a cherry-red spot surrounded by white opacification. Commotio retinae can occur outside the macula and is a broader disease concept.

2. Main Symptoms and Clinical Findings

Fundus findings suggestive of commotio retinae

Liu Y, et al. Creation of a New Explosive Injury Equipment to Induce a Rabbit Animal Model of Closed Globe Blast Injury via Gas Shock. Front Med (Lausanne). 2021. Figure 5. PMCID: PMC8495021. License: CC BY.

Fundus images of a rabbit exposed to 5,000 KPa pressure: (A) hazy fundus on day 3, (B) mild vitreous hemorrhage, (C) fundus opacity on day 3 suspicious for commotio retinae, (D) extensive retinal pigmentation. This corresponds to commotio retinae discussed in the section “2. Main symptoms and clinical findings”.

Subjective symptoms

• Visual field scotoma: Visual field defect or depression corresponding to the lesion. May be relatively unnoticed in extramacular lesions.
• Decreased visual acuity: Prominent when the lesion involves the macula.
• Blurred vision: Often present immediately after injury.
• Transient course: Subjective symptoms often improve within 1–2 weeks after injury. However, permanent visual impairment may remain in macular lesions.

Clinical findings

Fundus examination reveals characteristic shiny, small patchy to geographic white opacities. Opacities appear immediately after injury, peak at 2–3 days, and resolve over 1–2 weeks. Usually no hemorrhage.

In macular lesions (Berlin’s edema), a cherry-red spot-like appearance occurs due to relative redness of the fovea, with prominent contrast against the surrounding white opacities.

OCT typically shows hyperreflectivity and thickening of the ellipsoid zone (EZ) and disruption of the interdigitation zone (IZ). The OCT grading by Ahn et al. is useful for prognosis. ¹⁾

Mild Grade 1-2

Grade 1 (EZ hyperreflectivity): EZ hyperreflectivity is present but structure is preserved. Visual prognosis is relatively good.

Grade 2 (IZ loss): IZ reflectivity is lost. Indicates moderate photoreceptor outer segment damage.

Severe Grade 3-4

Grade 3 (IZ+EZ loss): Both IZ and EZ are lost. Visual prognosis tends to be poor.

Grade 4 (IZ+EZ+ELM loss): The most severe type, with loss up to the external limiting membrane (ELM). Visual prognosis is the poorest.

OCTA may help assess changes in macular vascular density. Also, choroidal thickening may be present in the early stages of injury.

Q How long does it take for vision to recover?

A

Macular lesions may result in permanent visual impairment. Higher OCT grades (Grade 3–4) indicate a poorer prognosis, making OCT evaluation at the time of consultation important. ¹⁾

3. Causes and Risk Factors

Mechanism of Injury

Commotio retinae is caused by closed ocular trauma or blast injury.

• High-impact sports: Ball sports (baseball, tennis, squash, etc.) are the most common. Occurs when a ball or equipment directly hits the eye.
• Assault/violence: Direct blow to the eye area from a fist or object.
• Motor vehicle accidents: Impact from airbag deployment or collision.
• Explosions/blast injuries: Can occur in military-related injuries or industrial accidents.

Prevention and Daily Care

Many sports-related eye injuries can be prevented with appropriate protective eyewear. Choosing materials according to the level of impact is important.

• Low to moderate impact (general ball sports): Polycarbonate lenses 2–3 mm thick are recommended.
• Moderate to high impact (hard balls, high-speed sports): Polycarbonate lenses 3 mm or thicker are required.
• Highest-risk sports (e.g., ice hockey, lacrosse): Wearing a helmet with a face mask is recommended.

If you hit your eye during sports, see an ophthalmologist as soon as possible, regardless of pain or visual abnormalities.

Q Which eye protection should I choose for sports?

A

It is recommended to choose polycarbonate lenses according to the impact level. For low to medium impact, 2–3 mm thickness is appropriate; for high impact, 3 mm or more. For highest-risk sports such as ice hockey and lacrosse, a helmet with a face mask is suitable. Regular eyeglass lenses are insufficient as protective gear, so dedicated protective eyewear should be used.

4. Diagnosis and Examination Methods

Basic Diagnostic Procedures

Dilated fundus examination is the standard. Diagnosis is often relatively easy due to the characteristic finding of a shiny white opacity.

In trauma examination, it is important to simultaneously check for intraocular complications other than retinal ones.

• Hyphema: Reflects damage to the angle or iris vessels.
• Angle injury: Requires evaluation by gonioscopy. Can cause traumatic glaucoma.
• Lens dislocation/subluxation: Occurs due to zonular rupture from strong blunt force.
• Vitreous hemorrhage: If fundus observation is difficult, use ultrasound examination.

Imaging Tests

• OCT (Optical Coherence Tomography): Typical findings include hyperreflectivity and increased thickness of the EZ. Grading based on the presence or absence of IZ/ELM loss is useful for predicting visual prognosis. ¹⁾
• Ultrasound (B-scan): Used when the fundus is poorly visible due to anterior segment opacity or vitreous hemorrhage.
• OCTA: Used adjunctively for macular vascular density assessment and follow-up.

Differential Diagnosis

In post-traumatic retinal whitening, the following differential diagnoses are important.

The table below shows the main differentiating points between commotio retinae and retinal contusion necrosis.

Feature	Commotio Retinae	Contusion Necrosis
Opacity appearance	Shiny white	Dense white
Hemorrhage	None	Present
Prognosis	Spontaneous resolution	Irreversible

Other differential diagnoses include the following.

• Retinal ischemia: White opacity due to vascular occlusion. Accompanied by vascular findings.
• Choroidal rupture: Crescent-shaped white line. Becomes apparent several weeks after trauma.
• Purtscher retinopathy: Multiple white spots and hemorrhages occurring after head trauma or chest compression.
• Traumatic macular hole: Full-thickness defect in the macula. Can be confirmed by OCT.

5. Standard Treatment

Currently, there is no established treatment with proven efficacy for commotio retinae. The opacities usually resolve spontaneously, and observation is the basic management.

White opacities often resolve spontaneously within 1 to 2 weeks after injury. Improvement in OCT findings may continue for several months thereafter.

There are anecdotal reports of high-dose intravenous steroid administration, but its efficacy is not established and it is not currently recommended as standard treatment.

The most important aspect of observation is detection and management of complications.

• Macular hole: May occur during the post-traumatic course. If symptoms worsen again, perform OCT promptly.
• Retinal tear/detachment: Blunt trauma may be accompanied by lattice degeneration or tears in the peripheral retina. Perform regular dilated peripheral fundus examinations.
• Secondary glaucoma: May develop secondary to angle damage. Regular intraocular pressure checks are necessary.

Treatment Precautions

• Commotio retinae may be accompanied by complications such as lens dislocation, retinal tear, or angle damage. It is important to continue regular ophthalmologic follow-up after injury.
• In particular, complications affecting the entire eyeball such as lens dislocation may be present, so do not conclude the evaluation of ocular trauma based solely on retinal findings.
• Even if the patient feels that the condition has “improved,” retinal tears or detachment may progress asymptomatically.
• Vigorously rubbing or pressing the eye may worsen complications.
• Refrain from using contact lenses until inflammation or the condition has subsided.

Q If there is no treatment, is it okay not to see a doctor?

A

An ophthalmological examination is essential. Commotio retinae itself often resolves spontaneously, but complications such as retinal tears, macular holes, angle damage, and lens dislocation may also occur. Missing these can lead to permanent visual impairment or visual field defects. In particular, regular follow-up after injury is directly linked to early detection of complications.

6. Pathophysiology and Detailed Mechanism of Onset

Mechanical Mechanism

Blunt impact to the eye applies mechanical stress to the retina through the following mechanisms:

1. Rapid deformation of the eyeball: The impact causes the lens and iris diaphragm to rapidly displace posteriorly.
2. Generation of hydrodynamic forces: Sudden pressure changes in the intraocular fluid occur.
3. Bidirectional pressure on the retina: Pressure from the vitreous side and repulsive force from the scleral side sandwich the retina.

Contrecoup injury occurs when the shock wave passes through the eyeball and reaches the opposite retina.

Histological Changes

Mansour et al. confirmed destruction of photoreceptor outer segments and accumulation of subretinal debris in donor eyes processed within 24 hours after injury²⁾.

• Fracture of photoreceptor outer segments: This is the most vulnerable site. Photoreceptor processes (outer segments) are not supported by Müller cells, making them susceptible to mechanical stress.
• Mild damage to the retinal pigment epithelium: Retinal pigment epithelial cells show relatively mild changes.
• Preservation of the blood-retinal barrier: In commotio retinae, significant disruption of the blood-retinal barrier is not thought to occur. This is one reason why bleeding is absent.

Optical mechanism of white opacity

The glossy white opacity of the fundus results from abnormal light scattering caused by disrupted outer segments and debris. The essence is physical disruption of outer segment structures, not fluid accumulation (edema) within the tissue.

Recovery process of outer segments

Repair of outer segments begins approximately 1 week after injury. Complete recovery may take more than 2 months.

In normal photoreceptor outer segments, there are 1,000–2,000 disc membranes, and about 10% of the distal outer segment is phagocytosed by the retinal pigment epithelium daily for renewal. This turnover cycle renews the entire outer segment in about 10–14 days. This physiological outer segment renewal mechanism is thought to underlie the natural resolution after trauma.

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7. Latest research and future perspectives (reports under investigation)

For patients: Please read this

The following content is currently under investigation or in clinical trials and is not standard treatment available at general hospitals. It is reference information for professionals regarding future medical developments.

Follow-up evaluation using OCTA

OCTA may be useful as a non-invasive follow-up tool. However, the clinical significance of prognostic prediction in commotio retinae requires further investigation.

Prognostic prediction using OCT grading

The OCT grading system by Ahn et al. has attracted attention as a tool for predicting visual prognosis from acute-phase findings. ¹⁾ In particular, identification of severe cases (Grade 3–4) is thought to help determine the need for early intensive follow-up. Validation through future multicenter prospective studies is required.

Choroidal Blood Flow Change Hypothesis

Changes in choroidal blood flow after blunt trauma may contribute to dysfunction of the retinal pigment epithelium and photoreceptor outer segments. This hypothesis is useful for understanding the pathophysiology, but it has not yet been established as a therapeutic target.

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8. References

1. Ahn SJ, Woo SJ, Kim KE, et al. Optical coherence tomography morphologic grading of macular commotio retinae and its association with anatomic and visual outcomes. Am J Ophthalmol. 2013;156(5):994-1001.e1.
2. Mansour AM, Green WR, Hogge C. Histopathology of commotio retinae. Retina. 1992;12(1):24-28.