Other / Other / MRI

Retinal detachment

Retinal detachment presents with photopsia, floaters, and progressive peripheral visual field loss; imaging is indicated when an underlying cause such as malignancy needs to be ruled out or for surgical planning.
Look For First
  • Bright, continuous, smooth folded membrane within the vitreous on ultrasound with independent aftermovement
  • Triangular or V-shaped configuration with insertion into the optic disc on ultrasound
  • Folded membrane with subretinal fluid (hyperdense on CT) converging posteriorly on the disc on cross-sectional imaging
Key Image Findings
  • Ultrasound shows a bright, reflective, freely moving membrane within the vitreous that demonstrates aftermovements with extraocular muscle recruitment, distinguishing acute from chronic detachment
  • Acute retinal detachment is mobile on ultrasound real-time imaging with pronounced movements, whereas long-standing detachments show progressively decreased mobility
  • Total or extensive detachment appears as a characteristic triangular or V-shaped configuration with insertion at the optic disc and anterior extent limited by the ora serrata
  • On CT/MRI, folded membrane with subretinal space fluid (hypodense on MRI, hyperdense on CT) that converges posteriorly on the optic disc, distinguishing it from choroidal detachment which diverges at the disc
  • The anterior limit of retinal detachment is bounded by the ora serrata, while choroidal detachment extends beyond the ora serrata
  • Post-treatment imaging may demonstrate a scleral band from scleral buckle surgery used to relieve vitreous traction and promote closure of retinal defects
Differential Diagnosis
  • Choroidal detachment: does not demonstrate aftermovements on ultrasound and diverges at the optic disc (rather than converging) and extends beyond the ora serrata on cross-sectional imaging
  • Posterior vitreous detachment: less mobile than acute retinal detachment and lacks the characteristic triangular configuration with optic disc insertion
  • Vitreous hemorrhage: appears as echogenic material without the characteristic smooth membrane architecture or aftermovements
  • Retinal tear without detachment: similar photopsia and floaters but no membrane or subretinal fluid on imaging
Discussion

Rhegmatogenous retinal detachment (most common type) results from fluid ingression through a retinal break in the setting of posterior vitreous detachment, trauma, or predisposing lesions like lattice degeneration

Myopia is the most common risk factor; post-cataract surgery patients (aphakic or pseudophakic) are at significantly increased risk due to loss of the supportive lens

Macula-on retinal detachments where the fovea remains attached have better prognosis and visual outcomes compared to macula-off detachments involving the central retina

Non-rhegmatogenous detachments (tractional and exudative) are secondary phenomena from conditions like proliferative diabetic retinopathy, sickle cell retinopathy, central serous chorioretinopathy, or choroidal neoplasms

Ultrasound's real-time evaluation with aftermovements is key to acute detection and differentiation from structural mimics, making it the primary imaging modality when clinical suspicion is high

Cross-sectional imaging (CT/MRI) is reserved for evaluating underlying orbital pathology or when malignancy such as choroidal melanoma is in the differential

Reporting Pearls

Report the location and extent of retinal detachment (macula-on vs. macula-off, quadrant, and percentage involvement), describe the morphology (triangular/V-shaped with optic disc convergence), confirm mobility/aftermovements on ultrasound to establish acuity, and note any associated findings such as subretinal fluid characteristics or signs of underlying choroidal pathology.

Pitfalls
  • Confusing retinal detachment with choroidal detachment: remember that choroidal detachment does NOT show aftermovements and diverges at the optic disc, whereas retinal detachment converges at the disc
  • Mistaking a long-standing detachment for a posterior vitreous detachment: chronic detachments show decreased mobility; comparison with real-time ultrasound motion and morphology helps differentiate
  • Over-relying on cross-sectional imaging when ultrasound is superior for detecting mobility and confirming acute detachment; ultrasound should be first-line imaging
  • Failing to distinguish macula involvement: macula-on vs. macula-off status critically impacts prognosis and requires careful anatomic assessment of foveal attachment