Ultrasound examination of the ocular globe is an accessible,
non-invasive and useful technique,
in situations that prevent a normal eye examination,
or when examination findings suggest particular pathology of the eye.
there is certain ignorance in this area among radiologists,
as long as ophthalmologists are responsible for making the diagnosis without resorting to ultrasound imaging technique,
or by using more invasive or expensive imaging methods.
Indications of ocular ultrasound:
- Situations that prevent a normal eye examination due to the opacity of anterior segment structures (leucoma,
cataract) or posterior segment structures (hemovitreous,
- To provide useful information when examination findings suggest particular pathology of the eye (identification and monitoring tumors,
evaluation of choroidal detachment,
Contraindications and limitations of ocular ultrasound:
Ultrasound examination should not be performed in cases of suspected diagnosis of post-traumatic or postoperative ocular perforation.
Ocular ultrasound is not useful in evaluating bony orbital walls and posterior orbit.
At the present time the anterior segment evaluation has practically no indications because of development of ultrabiomicroscopy.
Proper technique of performing ocular US
A high-resolution 7.5-10 Mhz linear array ultrasound transducer is used to perform an ocular examination.
B-mode ultrasound should be performed in a supine patient with closed eyes,
taking transverse and sagittal views.
Eye movements in different directions and colour Doppler help us to get more info.
It is important to adjust the device controls and settings: gain and focus.
The gain manage is very important in mode-B ocular ultrasound.
The study starts with a medium gain,
that shows the view of medium and high echogenicity structures,
and then it is maximized to visualize very low-echogenicity structures (early vitreous or subvitreous hemorrhage,
Normal sonographic anatomy of ocular globe
The eye ball is divided by the lens into two segments:
- Anterior segment: subdivided by the iris in anterior and posterior chamber.
It includes the cornea,
cilliary body and lens.
It contains a fluid called aqueous humor.
- Posterior segment: also contains more consistent fluid called vitreous humor.
vitreous humor and the cornea are the transparent structures of the eye.
The eyeball wall is composed by three layers:
- The external layer: a fibrous layer that is very resistant and keep the shape of the eye.
It is formed by the sclera at the back and the cornea in the anterior part.
- The intermediate layer: the uveal tract is a vascular layer,
divided in anterior part (iris and cilliary body) and posterior part (choroid).
- The internal layer: a neural layer,
which contains different structures in its surface: macula,
fovea and papilla or optic disk.
The structures of the eye are easily visible on ultrasound.
The previous structure is the cornea,
shown as a thin line,
it can sometimes be unidentifiable.
The anterior segment comprises two anechoic areas: the anterior chamber (between the cornea and the iris) and the lens,
an anechoic structure with thin anterior and posterior capsules.
Cilliary bodies are on both sides of the lens shown as hypoechoic structures.
The vitreous is seen as an anechoic region posterior to the lens.
The posterior wall (three layers) appears as a concave echogenic line,
interrupted by the optical disk.
Ultrasonographic semiology of the ocular diseases
Morphologic features of the ocular lesions
- Point-like echoes: small lesions with a variable echogenicity according to their composition.
Low-echogenicity echoes may be due to degenerative conditions like early vitreous hemorrhage or hyalitis,
and high or medium-echogenicity echoes may be caused by evolving vitreous hemorrhage and endophthalmitis evolved.
- Membrane-like echoes: linear images,
with a variable length,
thickness and echogenicity according to their etiology.
the posterior vitreous detachment shows a low-echogenicity membrane while the retinal detachment exhibits a higher echogenicity and thicker membrane.
- Solid echoes: bigger images than point-like echoes.
They can be focal or diffuse.
Kinetic-mobility of ocular lesions
After evaluating the morphology of the lesion,
proceed to ask the patient to do eye movements in all axes.
It is important to show hidden membranes on the posterior wall in the rest position.
The movement that membranes do to return to its position is called after-movement.
After-movement can be fluid (degenerative posterior vitreous detachment),
rigid (early retinal detachment) or be absent (choroidal detachment).