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ultrasonography focused on the posterior eye segment: what radiologists should know. Choroidal detachment. a Diagram showing typical bilateral exudative choroidal detachment, with two convex rigid lines protruding into the vitreous, extending from the scleral spur near the ciliary body (arrows) to the level of the exit foramina of the vortex veins (arrowheads), at some distance from the papilla. b US image in a 69-year-old woman with glaucoma in the right eye 1 day after cataract surgery shows two lines ballooning into the vitreous, demonstrating an exudative choroidal detachment (arrows)

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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:

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

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.

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
inflammatory choroidal disorders
caroticocavernous fistula
severe atherosclerosis

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 :

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
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 (compared to the retinal detachment that is limited)
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 neurovascular structures at the ciliary body
choroidal effusions appear on CT as hypodense linear fluid collections elevating a thick hyperdense choroid. On MRI, they usually will exhibit low T1 and high T2 signal
choroidal hemorrhage classically appears as a hyperdense lentiform lesion on CT and, on MRI, will show hemoglobin products throughout the sequences, typically with a high T1 signal

Treatment and prognosis

In non-traumatic cases, the cause is treated and IOP is reduced with appropriate medication. Trauma cases may be treated with surgery, like non-traumatic cases persisting for a week or more, where the fluid may be drain and a tamponade method performed.

Un- or under-treated choroidal detachment can damage the cornea and cause cataracts.