Choroidal detachment is a detachment of the choroid from the underlying sclera due to the accumulation of fluid in the suprachoroidal space, generally due to increased intraocular pressure (IOP), as observed in some settings:
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choroidal effusion
transudative: trauma
exudative: fluid accumulating in the suprachoroidal space secondary to many causes, most commonly inflammation (e.g. uveitis)
choroidal hemorrhage: trauma and surgery
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Terminology
Please note that this article will prefer the term choroidal detachment regardless its fluid content, with choroidal effusion and choroidal hemorrhage used as its subtypes. In ophthalmological practice this latter type is termed suprachoroidal hemorrhage, the suprachoroidal space being a potential space between the sclera and choroid.
Pathology
Etiology
Depending or not on the rupture of small choroidal vessels, the content within the detachment may be hemorrhagic or effusion. Some of the more common causes of choroidal detachment are:
trauma
surgery
spontaneous (Valsalva, etc.)
medications for lowering IOP
hypertension
ocular hypotony: small globe with a characteristic umbrella sign or scleral infolding
ocular neoplasms (lymphoma, carcinoma)
Radiographic features
Imaging is usually not required unless a specific underlying cause, such as a metastasis is considered.
Ultrasound
A high frequency, small footprint probe, performed through the closed eyelid provides excellent detail, typically demonstrating the following sonographic features 5:
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paired, convex echogenic bands extending posteriorly from the ciliary bodies
the posterior points of attachment are distal to the optic disc, corresponding to the insertion of the vortex veins, to which the sclera and choroid are tightly adherent
anteriorly, the detached membrane extends beyond the ora serrata (distinguishing it from a retinal detachment, which is limited by the ora serrata)
remain fixed in position during eye movements, allowing differentiation from retinal and posterior vitreous detachments
CT/MRI
the detachment is not limited anteriorly by the ora serrata (unlike a retinal detachment)
posteriorly the detachment diverges as it approaches the optic disc (compared to the retinal detachment that converges to the disc) due to the insertion of the vortex veins
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choroidal effusions
CT: hypodense convex fluid collections elevating a relatively hyperdense choroid
MRI: low T1 and high T2 signal
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choroidal hemorrhage
CT: hyperdense lentiform lesion
MRI: signal may be heterogeneous but typically hyperintense on T1 and hypointense on T2 (depending on the age of the blood)
Treatment and prognosis
In non-traumatic cases, the cause is treated and IOP is reduced with appropriate medication. If persistent, surgery may be required.
Trauma cases may be treated surgically.
Un- or under-treated choroidal detachment can damage the cornea and cause cataracts.