Choroidal Detachment Pathophysiology
Choroidal detachment occurs when fluid or blood accumulates in the suprachoroidal space—the potential space between the choroid and sclera—most commonly triggered by hypotony combined with inflammation, disrupting the delicate balance of intraocular pressure and choroidal vascular integrity. 1
Fundamental Pathophysiologic Mechanism
The core pathophysiology revolves around fluid leakage from the choriocapillaris into the suprachoroidal space 2. This process is driven by:
- Hypotony as the primary trigger: Low intraocular pressure creates a pressure gradient that favors fluid transudation from choroidal vessels into the suprachoroidal space 1, 2
- Inflammatory component: Postoperative or disease-related inflammation increases vascular permeability, exacerbating fluid accumulation 2
- Vascular instability: An unstable choroidal vascular system, particularly in myopic eyes, predisposes to detachment 3
Etiologic Categories and Mechanisms
Surgical Causes (Most Common)
- Post-trabeculectomy: The most frequent cause, where surgical hypotony combines with postoperative inflammation 1
- Other intraocular surgeries: Cataract extraction, retinal detachment repair, and glaucoma procedures all create risk through similar mechanisms of hypotony and inflammation 2, 4
Idiopathic Causes
- Uveal effusion syndrome: Caused by scleral abnormalities with hypoplasia or partial absence of the vortex venous system, leading to impaired choroidal drainage 2
- Microphthalmia: Anatomic predisposition to fluid accumulation 2
Inflammatory Conditions
- Scleritis, sympathetic ophthalmia, pars planitis, Harada's disease: These conditions increase choroidal vascular permeability through inflammatory mediators 2
Trauma and Other Causes
- Direct ocular trauma: Disrupts normal anatomic barriers 1
- Corneal ulcers and IOP-lowering agents: Create hypotony through different mechanisms 5
Clinical Presentation Spectrum
The pathophysiology manifests across a wide clinical spectrum 1:
- Asymptomatic cases: Minimal fluid accumulation with preserved IOP
- Severe presentations: Marked visual loss, profound hypotony, severe ocular pain, nausea, and vomiting
- Associated findings: Serous retinal detachment (from choroidal elevation), secondary angle closure (from anterior rotation of ciliary body), and markedly shallow anterior chamber 1, 3
Special Consideration: Myopic Eyes
Myopic patients with choroidal detachment present with particularly poor prognosis due to inherent choroidal vascular instability and higher risk of proliferative vitreoretinopathy 3. The pathogenesis in these patients involves the combination of hypotony, myopic anatomic changes, and an already compromised choroidal vascular system 3.
Management Principles Based on Pathophysiology
Medical Management
Systemic corticosteroids (oral prednisone 1 mg/kg/day) should be initiated preoperatively to reduce inflammation and choroidal detachment, directly addressing the inflammatory component of pathophysiology 6.
Surgical Intervention
When medical management fails, surgical approaches target the underlying mechanisms:
- Vortex vein decompression and/or sclerotomy: Most effective for idiopathic cases by addressing venous drainage abnormalities 2
- Scleral buckling with cryotherapy: For cases with concurrent retinal detachment, performed under direct visualization to release both choroidal and subretinal fluid 3
Natural History Considerations
- Postoperative cases: Usually resolve spontaneously as IOP normalizes and inflammation subsides 2
- Idiopathic cases: Variable course with prolonged duration, remissions, and exacerbations, often requiring surgical intervention 2
Critical Pitfalls
Delays in diagnosis significantly worsen prognosis, particularly in cases with concurrent retinal detachment where proliferative vitreoretinopathy may develop postoperatively 3. Point-of-care ultrasound can expedite diagnosis when fundoscopic examination is limited 5.