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Eye Ultrasound (B-Scan): Seeing Inside the Eye When It Can't Be Seen Directly
Eye ultrasound uses harmless high-frequency sound waves to create a picture of the inside of your eye. It is the test your surgeon turns to when a dense cataract, bleeding inside the eye or a cloudy cornea blocks the normal view of the retina, and it is also used to measure the eye and to assess lumps or lesions. At Laser Istanbul Clinic it is used where your examination calls for it, and the surgeon who reads the images is the one who treats you.
An eye ultrasound, also called a B-scan, is a quick, painless scan that sends high-frequency sound waves into the eye and turns the echoes into an image. It shows the retina, the gel inside the eye, the lens and any growth even when a dense cataract or bleeding blocks the view. Retina specialists Doç. Dr. Muhammet Derda Özer and Op. Dr. Aysan Bayram review these scans, and the test takes only a few minutes.
What an eye ultrasound measures
An eye ultrasound works like an echo: a probe sends sound waves into the eye, tissues of different density reflect them back, and the machine converts the echoes into an image or a measurement. Because it uses sound rather than light, it can see through things that light cannot, such as a dense cataract or a cloud of blood. EyeWiki, the clinical wiki of the American Academy of Ophthalmology (AAO), notes that ultrasound is safe, uses no radiation, is widely available and is low cost.
There are three main types, and most patients have one or two of them.
| Type | What it shows | Typical use |
|---|---|---|
| B-scan ("brightness" scan, about 10 MHz) | A two-dimensional, cross-section picture of the eye: retina, vitreous gel, lens, optic nerve, any mass | Looking behind a cloudy view; retinal detachment, bleeding, tumours, foreign bodies, dislocated lens |
| A-scan ("amplitude" scan, about 8 MHz) | Not a picture but a line of spikes that measures distances and tissue structure | Measuring the length of the eye for lens-power calculation; characterising a tumour |
| Ultrasound biomicroscopy (UBM) (35–100 MHz) | A very detailed image of the front 4–5 mm of the eye: iris, drainage angle, ciliary body | Narrow-angle glaucoma, cysts and lumps at the front of the eye, injuries |
The frequencies come from EyeWiki. Higher frequencies give finer detail but do not travel as deep, which is why detailed front-of-eye imaging uses a different, higher-frequency probe from the standard B-scan.
Our examination uses {{ultrasound machine / probe model used by your surgeons}}.
Why you may need an eye ultrasound
Your surgeon may ask for an eye ultrasound for one of four main reasons.
1. To see the retina when something blocks the view
A normal eye examination relies on looking through the clear front of the eye to the retina. A very dense cataract, bleeding into the gel (vitreous haemorrhage) or a scarred cornea can make that impossible. EyeWiki lists dense cataract and vitreous haemorrhage as important indications for ultrasound whenever the back of the eye cannot be examined directly. A teaching guide from the University of Iowa's EyeRounds describes ultrasound as particularly useful when pathology prevents or obscures ophthalmoscopy.
2. To detect a retinal detachment
A B-scan can show a detached retina, and it can help tell different types of detachment apart. EyeWiki states that B-scan can distinguish a rhegmatogenous (tear-related) detachment from an exudative one, and a detachment from retinoschisis. In a 2020 systematic review and meta-analysis in JAMA Network Open (9 studies, 1,189 eyes), ocular ultrasound detected retinal detachment with a pooled sensitivity of 94% and specificity of 94%, and vitreous haemorrhage with a sensitivity of 90% and specificity of 92%. That review looked at scans performed by emergency doctors rather than eye specialists; in an eye clinic the scan is performed and read by the specialist team.
Retinal detachment is an emergency. The NHS lists the warning signs as floaters or flashes of light, a dark curtain or shadow moving across your vision, and blurred vision. If these appear suddenly, seek urgent medical help straight away. Do not wait for a travel plan.
3. Before cataract surgery
Most cataract patients never need a B-scan; they have a normal examination and optical measurements. It is used in two situations.
- When the cataract is so dense that the surgeon cannot see the retina. The scan checks that the back of the eye is healthy, because a retinal problem could limit how well you see after the lens is replaced. A leaflet from an NHS eye hospital describes ultrasound as useful as a simple screening test before planned procedures such as cataract surgery.
- When light-based measurement fails. The power of your new lens depends on the length of your eye. Optical biometry (such as the IOL Master) measures this with light, but dense cataracts scatter light. In a 2021 study in the Indian Journal of Ophthalmology, partial-coherence interferometry failed in 68.6% of eyes with dense cataracts and in 100% of the densest nuclear cataracts, whereas every measurement was possible with immersion ultrasound. This is the "eye ultrasound with water" some patients search for: in immersion A-scan, a small saline-filled cup sits against the eye and the probe is held in the fluid without touching the cornea. A trade journal review explains that this avoids the corneal compression of contact (applanation) measurement and can measure through almost any opacity.
4. To assess lumps, lesions and injuries
Ultrasound helps to find, measure and characterise growths inside the eye, including choroidal melanoma. EyeWiki reports that combined A-scan and B-scan examinations are more than 95% accurate in diagnosing choroidal melanomas thicker than 3 mm, and a 2025 review in Retina Today notes that B-scan can show tumours from 1.5 mm in thickness. Ultrasound measures the tumour so that changes can be tracked over time; it does not replace a full examination by an ocular oncology specialist. It is also used to look for a foreign body, a dislocated lens or damage after an injury.
What to expect: the eye ultrasound procedure
Eye ultrasound is quick and does not hurt. The exact method depends on what your surgeon needs to see.
Before the test
- You can eat and drink normally and take your usual medicines.
- Remove contact lenses. You will be asked to take them out, so bring your glasses and a lens case.
- Tell the team about any eye-drop allergy and about any difficulty lying down.
- Plan not to drive straight afterwards if your surgeon also dilates your pupils, because dilating drops blur vision for several hours (an NHS leaflet gives 6–8 hours).
- Bring any previous scans and your eye reports.
During the test (B-scan through the eyelid)
- You lie back or sit reclined, with your eyes closed.
- A little ultrasound gel is placed on your closed upper eyelid.
- The probe rests gently on the lid. You are asked to look up, down, left or right to bring each part of the retina into view.
- The images appear on a screen and are saved for your surgeon.
For some scans, the probe is placed directly on the surface of the eye after numbing drops, using artificial tears as the gel. This is also painless. Immersion A-scans and UBM use a small water or saline bath or cup placed against the eye. Numbing drops make the eye feel numb for about 20–30 minutes, so do not rub it until normal feeling returns.
How long does it take? An NHS patient leaflet says the procedure is not painful and takes only a few minutes. A systematic B-scan examination covers four transverse views around the eye and two axial views, according to EyeWiki.
Is it safe? The NHS leaflet describes eye ultrasound procedures as very safe, and the scan uses no radiation. The one situation needing special care is a suspected open injury to the eyeball, where pressure on the eye could cause further damage; in that situation EyeRounds advises that only an experienced echographer scan the eye. Tell your surgeon at once about any recent eye injury or surgery.
After the test: wipe off the gel and carry on as normal, apart from the effects of any dilating drops.
How eye ultrasound results are read
Reading a B-scan is a specialist skill. Your surgeon looks at the images together with your history and examination.
Brightness tells density. Dense tissue looks bright and fluid looks dark; very dense tissue casts a "shadow" behind it. The sensitivity (gain) is turned up to pick up faint structures such as small vitreous opacities, and turned down to assess solid masses (EyeRounds).
What your surgeon looks for:
| Finding on the scan | What it can mean |
|---|---|
| A thin, bright membrane inside the eye | Retinal detachment (the type and extent are then assessed) |
| Echoes floating in the vitreous gel | Vitreous haemorrhage or vitreous opacities |
| A normal, flat retina behind a dense cataract | Reassuring before cataract surgery: no hidden retinal problem seen |
| A solid, dome- or mushroom-shaped lesion under the retina | Possible choroidal tumour, measured and followed up |
| A bright object or an abnormal lens position | Foreign body or dislocated lens |
| Axial length in millimetres (A-scan) | Used to calculate the power of the new lens |
This table is a guide only. Ultrasound has limits: in the 2020 meta-analysis its sensitivity for detecting a vitreous detachment was lower (67%), and a B-scan alone cannot always tell every type of detachment apart. Your surgeon combines the scan with a full examination and, where needed, other tests.
When a tumour is suspected, ultrasound is one part of the work-up. Retina Today notes that tumour size and shape are easily seen on ultrasound, but genetic and molecular analysis may be needed for a full risk assessment.
Eye ultrasound price: how much does an eye ultrasound cost?
An eye ultrasound is included in your treatment price when your surgeon needs it as part of your pre-operative examination and scans. If you only want an ultrasound, for example a second opinion on a retinal problem or a check behind a dense cataract, a standalone examination with eye ultrasound costs {{£ price for a standalone eye ultrasound examination}}. Hotel and airport transfers are not included and are a separate charge if you would like us to arrange them.
You can also send recent scans from your own eye doctor for a free initial review before you travel.
Who reads your scans
Your images are read by the surgeon who will treat you. Doç. Dr. Muhammet Derda Özer (Doç. means Associate Professor) is our retina, uveitis and ocular oncology specialist and reviews scans for retinal disease, inflammation and eye lumps. Op. Dr. Aysan Bayram diagnoses and treats retinal disease and operates on cataracts, so she uses ultrasound when a cataract hides the retina. Prof. Dr. Ahmet Satıcı uses ultrasound-based measurements in planning cataract and lens surgery. If a scan shows something unexpected, your surgeon explains it in plain language, through your personal interpreter if you wish.
Treatments an eye ultrasound supports
| Treatment | How ultrasound is used |
|---|---|
| Retina surgery (vitrectomy, retinal detachment repair) | Shows the retina and the cause of vision loss when bleeding or a cataract blocks the view; guides the plan |
| Cataract surgery | Checks the retina behind a dense cataract; measures the eye when optical biometry cannot |
| Lens replacement and implantable-lens planning | Provides axial-length measurements when light-based methods fail |
| Treatment of intraocular lumps | Measures and follows a lesion; supports the specialist's decision |
Other tests in your eye examination
An eye ultrasound is one of several tests, each answering a different question:
- Corneal topography: maps the shape of the cornea (/en/eye-tests-diagnostics/corneal-topography/)
- OCT scan (optical coherence tomography): detailed cross-section scans of the retina when it can be seen clearly (/en/eye-tests-diagnostics/oct-scan/)
- FFA (fundus fluorescein angiography): imaging of the blood vessels at the back of the eye (/en/eye-tests-diagnostics/fluorescein-angiography/)
- Visual field test (perimetry): checks your side vision (/en/eye-tests-diagnostics/visual-field-test/)
- Tonometry (eye pressure measurement): important for glaucoma checks (/en/eye-tests-diagnostics/tonometry/)
- VEP & ERG electrophysiology tests: measure the electrical responses of the retina and visual pathway (/en/eye-tests-diagnostics/vep-erg-tests/)
In short: OCT is the choice when the retina is visible, ultrasound when it is not.
Eye ultrasound: frequently asked questions
An eye ultrasound (B-scan) is a painless scan that uses high-frequency sound waves to create a picture of the inside of the eye. It is used when the retina cannot be seen directly, for example behind a dense cataract or blood in the eye, and to measure the eye and assess lumps.
It shows the retina, the vitreous gel, the lens, the optic nerve and the back wall of the eye. It can reveal a retinal detachment, bleeding inside the eye, a tumour, a foreign body or a dislocated lens, and it can measure the eye's length.
No. A B-scan through the closed eyelid involves a little gel and gentle pressure. Scans placed directly on the eye are done after numbing drops. The drops last about 20–30 minutes, so avoid rubbing your eye until they wear off.
Typically only a few minutes, according to an NHS patient leaflet. Your appointment is longer because it includes your full examination.
Yes. It uses sound waves, not radiation. The only special caution is a suspected open eyeball injury, where an experienced operator must do the scan to avoid pressure on the eye.
Only if the cataract is very dense or optical measurements fail. The scan checks the retina behind the cataract and measures your eye's length so the new lens power can be calculated. In dense cataracts, light-based biometry often fails while immersion ultrasound still works.
It usually means immersion A-scan: a small cup of saline sits against the eye and the probe is held in the liquid. Because the probe does not touch the cornea, the cornea is not flattened, so the length measurement is more reliable. A B-scan through the closed eyelid uses gel instead.
A B-scan makes a two-dimensional picture of the inside of the eye. An A-scan produces a line of spikes that measures distance and tissue properties, such as the length of the eye. Both use ultrasound and are often combined.
It can find and measure many tumours inside the eye. EyeWiki reports that combined A-scan and B-scan are more than 95% accurate for choroidal melanomas thicker than 3 mm. It is one part of the assessment; your specialist may recommend further tests.
It is included in your treatment price when your surgeon needs it for your pre-operative examination. A standalone eye ultrasound examination costs {{£ price for a standalone eye ultrasound examination}}. Hotel and transfers are not included.
It is a compact ultrasound unit with a hand-held probe connected to a screen. A B-scan probe works at about 10 MHz and an A-scan probe at about 8 MHz. The scans you may see online for pets ("eye ultrasound dog" or "cat") are done by vets; we treat human eyes only.
Yes. Upload your prescription and any ultrasound, OCT or retina reports, and a surgeon will review them free of charge.
Sources for the facts on this page
- EyeWiki (AAO), Ophthalmologic Ultrasound: B-scan about 10 MHz, A-scan about 8 MHz; indications (retinal detachment, vitreous haemorrhage, choroidal melanoma, foreign body, lens dislocation); B-scan through the eyelid with gel; combined scans more than 95% accurate for choroidal melanoma thicker than 3 mm; safe, no radiation, low cost; dense cataract and vitreous haemorrhage as key indications; distinguishes rhegmatogenous from exudative detachment and from retinoschisis. https://eyewiki.org/Ophthalmologic_Ultrasound
- EyeWiki (AAO), Echography (Ultrasound): A-scan axial length before cataract surgery; probes 7.5–12 MHz; systematic scan of four transverse and two axial views; caution in acute open-globe trauma. https://eyewiki.org/Echography_(ultrasound)
- EyeWiki (AAO), Ultrasound Biomicroscopy: 35–100 MHz, 4–5 mm penetration; angle, iris, ciliary body; supine position; contact or immersion technique. https://eyewiki.org/Ultrasound_Biomicroscopy
- Fairbanks A, Myers L, Flanary W, Warner L, Boldt HC. Ocular Ultrasound: A Quick Reference Guide for the On-Call Physician. EyeRounds, University of Iowa: quick, non-invasive; useful when ophthalmoscopy is obscured; through the eyelid or on the eye with topical anaesthesia; open-globe caution; density and gain. https://eyerounds.org/tutorials/ultrasound/Ocular-Ultrasound.pdf
- Manchester University NHS Foundation Trust, Ultrasound scan of the eye (patient leaflet REH 007, reviewed July 2025): gel on closed eyelid; not painful, a few minutes; screening test before cataract surgery; very safe; numbing drops about 20–30 minutes; remove contact lenses; drop-allergy and lying-down notes; dilation may blur vision 6–8 hours. https://mft.nhs.uk/app/uploads/sites/2/2018/05/REH-007-Ultrasound-scan-of-the-eye.pdf
- Propst SL, Kirschner JM, Strachan CC, et al. Ocular Point-of-Care Ultrasonography to Diagnose Posterior Chamber Abnormalities: A Systematic Review and Meta-analysis. JAMA Netw Open 2020;3(2):e1921460: retinal detachment sensitivity 0.94 / specificity 0.94; vitreous haemorrhage 0.90 / 0.92; vitreous detachment sensitivity 0.67 (9 studies, 1,189 eyes; emergency-practitioner-performed scans). https://pmc.ncbi.nlm.nih.gov/articles/PMC12527417/
- González-Godínez S, et al. Ocular biometry in dense cataracts: comparison of partial-coherence interferometry, swept-source OCT and immersion ultrasound. Indian J Ophthalmol 2021: PCI failure 68.57% overall and 100% in the densest nuclear cataracts; all measurements possible with immersion A-scan. https://pmc.ncbi.nlm.nih.gov/articles/PMC8917608
- Ophthalmology Management, Measuring Axial Length (2012): applanation corneal compression; immersion measures through almost any axial opacity. https://ophthalmologymanagement.com/issues/2012/july/measuring-axial-length/
- Retina Today, The Role of Ultrasonography in Choroidal Melanoma (April 2025): B-scan shows tumours from 1.5 mm thick; size and shape on ultrasound; genetic analysis needed for full risk stratification. https://retinatoday.com/articles/2025-apr/the-role-of-ultrasonography-in-choroidal-melanoma
- NHS, Retinal detachment: warning signs (floaters, flashes, dark curtain, blurred vision); seek urgent help. https://www.nhs.uk/conditions/retinal-detachment/
Have scans already? Let a surgeon look at them, free
Upload your prescription and any eye ultrasound or retina reports. Doç. Dr. Özer, Prof. Dr. Satıcı or Op. Dr. Bayram will tell you what they show and which treatments may suit you, with no obligation.
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Prof. Dr. Ahmet Satıcı
Doç. Dr. Muhammet Derda Özer
Op. Dr. Aysan Bayram