Practical approaches to B-scan ultrasound in retina practice

B-scan ultrasonography is a valuable imaging tool in retina practice, particularly when direct visualization of the posterior segment is limited by media opacity, trauma, or other clinical factors. It can provide important structural and dynamic information about the vitreous, retina, choroid, optic nerve, and posterior segment lesions, helping clinicians refine diagnosis, assess urgency, and monitor disease over time.

We spoke with Dr Mohan about when B-scan is most useful, how to structure the assessment, and practical ways to improve image quality and diagnostic confidence in a busy retina clinic.

Don’t miss out on hearing about our latest peer-reviewed articles, expert opinions, conference news, podcasts and more.

Register Register

In which clinical situations do you use B-scan ultrasound in retina practice, and what information are you looking for?

B-scan ultrasonography is an invaluable investigation whenever posterior segment visualization is limited, or when additional structural information is required. Common indications include dense cataract, corneal opacity, vitreous hemorrhage, endophthalmitis, ocular trauma, unexplained visual loss, intraocular foreign bodies, and intraocular tumors.

I primarily use B-scan to assess:

• Vitreous status, including posterior vitreous detachment, vitreous hemorrhage, membranes, and vitreoretinal traction
• Retinal status, including whether the retina is attached or detached, and the extent and configuration of any retinal detachment
• Choroidal pathology, including choroidal detachment and suprachoroidal hemorrhage
• Intraocular masses, including lesion location, size, internal reflectivity, and associated findings
• Ocular trauma, including globe integrity and detection of intraocular foreign bodies
• Optic nerve and scleral abnormalities, such as optic nerve head drusen and posterior staphyloma
• Dynamic characteristics of membranes and lesions, which often help differentiate retinal detachment from vitreous pathology.

In cases of endophthalmitis, B-scan is particularly valuable when media opacity precludes fundus examination. It helps identify vitreous opacities, membranes, retinal detachment, choroidal detachment, or suprachoroidal fluid, providing important prognostic information and helping determine the urgency of surgical intervention.

B-scan is also extremely useful for follow-up. In eyes with a poor fundus view, serial examinations allow monitoring of vitreous hemorrhage clearance, progression of traction, development of retinal detachment, response to treatment, and timing of surgery. For intraocular tumors and other posterior segment lesions, ultrasound provides objective measurements for documenting lesion growth and monitoring response to therapy over time.

How do you structure a B-scan assessment when the fundus view is limited by vitreous hemorrhage, dense cataract, corneal opacity, or trauma?

A standardized, systematic approach is essential.

I typically assess:

• The presence of lens or intraocular lens reverberations, or aphakia
• The vitreous, evaluating for vitreous hemorrhage, inflammatory debris, membranes, posterior vitreous detachment, or traction. The density, distribution, and reflectivity of vitreous echoes can provide clues to the underlying pathology
• The retina, including whether it is attached or detached, and the location, extent, and configuration of any retinal detachment. I assess membrane thickness, insertion to the optic disc, mobility, and reflectivity, as retinal detachments typically demonstrate high reflectivity and restricted mobility
• The choroid, assessing for choroidal detachment, suprachoroidal hemorrhage, or thickening. Choroidal detachments are characteristically smooth, dome-shaped, highly reflective membranes with poor mobility
• The posterior pole and optic nerve region, evaluating for masses, optic disc drusen, posterior staphyloma, scleral abnormalities, or other posterior segment pathology. Internal reflectivity and lesion morphology are important when assessing intraocular tumors
• Dynamic examination, observing after-movements and membrane mobility to distinguish retinal detachment from vitreous membranes or posterior vitreous detachment in difficult cases. Dynamic scanning often provides diagnostic information that static images cannot
• In trauma cases, scleral disruption or disorganized globe architecture, and the presence and reflectivity of intraocular foreign bodies
• Axial length measurement.

I perform longitudinal, transverse, and axial scans in all quadrants and document findings with representative images where possible.

What are the most common errors clinicians make when performing or interpreting posterior segment B-scan ultrasound?

Common pitfalls include:

• Incomplete scanning of all quadrants, leading to missed peripheral pathology
• Failure to perform dynamic scanning, which is often important for diagnosis and helps differentiate doubtful membranes, such as vitreous detachment versus retinal detachment
• Misinterpreting choroidal detachment, tractional retinal detachment, and posterior vitreous detachment because of unfamiliarity with their characteristic mobility patterns
• Excessive gain settings, resulting in artifacts
• Not confirming findings in multiple orientations
• Improper documentation of lesion location and extent
• Applying excessive probe pressure, particularly in trauma cases.

What practical tips can improve image quality, documentation, and confidence in a busy retina clinic?

A few practical tips can significantly improve efficiency and accuracy:

• Use a systematic scanning protocol for every patient
• Start with the lens shadow and evaluate each part of the ultrasound carefully
• Begin with higher gain to identify pathology, then reduce gain to refine structural details
• Always assess dynamically with eye movements
• Perform longitudinal, transverse, and axial scans in all quadrants to avoid missing pathology
• Correlate ultrasound findings with the clinical history, examination findings, and surgical findings when indicated
• Document and save representative images from multiple quadrants, and include measurements when relevant, such as for intraocular foreign bodies or masses
• Record lesion location using clock hours and quadrant-based documentation
• Always compare with the fellow eye.