Retinal detachment - Clinical Tree

Key points

Definition: Retinal detachment (RD) is a condition in which the inner retinal layer peels away from the middle choroidal layer of the globe permitting fluid to accumulate in what was previously only a “potential space.” It is a true medical emergency, progressing to vision loss and permanent blindness if not repaired within 24 to 72 hours.
Classic clue: Middle-aged or older patient presents with flashes, floaters, and hairs and a “heavy” eye. Computed tomography (CT) shows high-attenuation, “tulip-shaped” intraocular density stopping sharply at the ora serrata.

CT and magnetic resonance imaging (MRI) features of RD depend on what fluid is found below the detachment.
The fluid found beneath the retina often depends on the cause of the RD.
The radiologic differential diagnosis of RD depends more on appreciating the anterior margin than on recognizing a particular shape.
The anterior margin of an RD must stop at the ora serrata.
The anterior margin of a choroidal detachment (CD) must stop at the limbus, which is 8 to 9 mm anterior to the ora serrata.
RD typically demonstrates a tulip shape.
The CD extends anterior to the ora serrata and has a “slalom-course” shape.
The ophthalmoscope cannot see behind the retina, except through a tear. CT and MRI can easily evaluate the entire orbit.

CT attenuation of the RD depends on what fluid is below the detachment.
- The fluid beneath the RD often depends on the cause of the RD.
- Recent hemorrhage demonstrates high attenuation (see Figure 10-1 ).
- Retinal tears may permit low-attenuation vitreous humor to burrow beneath the retina (see Figure 10-1 ).
- May have a combination of high-attenuation hemorrhage and low-attenuation vitreous humor (see Figure 10-1 ).
- An effusion may have low CT attenuation.
The CT diagnosis of RD depends more on delineating the anterior margin.
- Anterior margin of RD must stop at the ora serrata (see Figure 10-1 ).
- Anterior margin of a CD may continue to the limbus, located 8 to 9 mm anterior to the ora serrata.

Melanomas may cause RD with hemorrhage or effusion.
Melanomas may be indistinguishable from hemorrhage, without contrast.
See Chapter 18 : Ocular Melanoma.
CT is not the imaging modality of choice but is frequently the imaging modality that is most readily available.

MRI is the assessment modality of choice. Compared with ultrasound (US), it has the advantage of imaging the complete orbit and the benefit of contrast. Compared with CT, it has the advantages of lack of ionizing radiation and of multiple, complex imaging sequences.
The MRI signal of RD depends on what fluid is below the detachment.
- The fluid beneath the RD often depends on the cause of the RD.
- Recent hemorrhage demonstrates high T1 signal.
- Retinal tears may permit vitreous humor to burrow beneath the retina causing the MRI signal to resemble that of the vitreous humor (reduced T1, increased T2).
- An RD containing an effusion typically has increased T1 signal related to increased protein levels. Effusions can generally be distinguished from tumors by T1 gadolinium enhancement, in which tumors appear bright, whereas effusions are not enhanced.
The MRI diagnosis of RD depends more on delineating its anterior margin.
- The anterior margin of RD must stop at the ora serrata.
- The anterior margin of a CD may continue to the limbus, located 8 to 9 mm anterior to the ora serrata.

Bright, continuous, smooth, folded membrane within vitreous.
Real-time imaging shows reflective, free-floating, folded membrane.
Membrane movement decreases with increasing time.
Extensive detachments form triangle with attachments to optic disc posteriorly and ora serrata anteriorly.

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