Laboratory Studies
Amylase level: Purtscher-like retinopathy is associated with acute pancreatitis; thus, an elevated amylase level may be diagnostic of this condition.
Complement C5a level: Activated complement C5a is associated with the development of Purtscher-like retinopathy in numerous conditions. This test may be diagnostic in presentations without an antecedent history of trauma.
A positive antinuclear antibody (ANA) test is helpful in establishing the diagnosis of certain collagen vascular diseases, such as lupus (>95% positive) and scleroderma (about 40% positive). Dermatomyositis rarely shows a positive ANA.
Similarly, anti–double-stranded DNA antibody is frequently positive in lupus (>75% positive) and scleroderma (about 15-50% positive).
Rheumatoid factor is positive in approximately 40% of patients with dermatomyositis.
Evidence of muscle disease and breakdown may be present in patients with dermatomyositis, to include the following:
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Elevated serum transaminase
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Elevated serum creatine phosphokinase
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Elevated serum aldolase
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Elevated serum myoglobin
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Elevated urine myoglobin
In patients with lupus, antiphospholipid antibodies may be associated with an increased risk of retinal vascular thrombosis.
Imaging Studies
If the patient has a history of head trauma or thoracic trauma, obtain appropriate x-ray films or imaging studies.
Skull or rib fractures may be present.
Severe crushing injuries of the chest in people who are unrestrained during MVAs may be associated with severe deep vascular injury, cardiac or pulmonary contusion, and abdominal organ injury. These injuries may require more extensive investigation.
Other Tests
Electromyographic (EMG) studies may be helpful in establishing the diagnosis of dermatomyositis.
Procedures
Fluorescein angiography studies (early in the disease) demonstrate capillary leakage and staining of the retinal arteries. In severe disease, the following are often noted together:
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Nonperfusion of the small arterioles that surround the central macula
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Perivenous staining
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Venous dilation and leakage
Fluorescein angiogram of a patient who sustained blunt chest compression as an unrestrained driver in a motor vehicle accident shows focal microvascular occlusion in the area of the cotton-wool spot. Mild venous leakage and staining is seen in the perifoveal capillary bed just beneath the central fovea. A small amount of fluorescein leakage is also seen beneath the fovea.
Histologic Findings
Histopathologic examination of an eye with prior Purtscher retinopathy shows evidence of inner retinal atrophy, which is consistent with inner retinal arterial occlusion. Late findings include nerve fiber layer dropout and evidence of optic atrophy.
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Characteristic fundus findings of Purtscher retinopathy. Multiple cotton-wool spots surround the optic nerve after blunt thoracic trauma.
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Mild Purtscher retinopathy in a patient after blunt chest compression as an unrestrained driver in a motor vehicle accident. This patient presented with visual loss in the left eye and had unilateral disease. The fundus photograph shows a large cotton-wool spot along the inferotemporal arcade and more subtle microvascular injury between the disc and fovea in the central macula. Whitening of the central fovea is present. Visual acuity was 20/200 but returned to 20/30 after 6 weeks.
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Fluorescein angiogram of a patient who sustained blunt chest compression as an unrestrained driver in a motor vehicle accident shows focal microvascular occlusion in the area of the cotton-wool spot. Mild venous leakage and staining is seen in the perifoveal capillary bed just beneath the central fovea. A small amount of fluorescein leakage is also seen beneath the fovea.
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Purtscher-like retinopathy in a patient with systemic lupus erythematosus with microvascular encephalopathy and retinopathy. Multiple cotton-wool spots of varying sizes and ages surround the optic nerve. A branch arterial occlusion is present along the supertemporal arcade with retinal whitening between the major artery and vein. Multiple occlusions are seen in arterial and venous trees with disruption of the blood columns.
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Patient perception of visual deficits in an eye with Purtscher retinopathy
