Eye pathology
Anterior Eye
The primary ultrasound anatomy of this area is:
- Cornea
- Aqueous humor
- iris
- Ciliary bodies
Ultrasound image- A post surgical tear of the iris. Red arrow indicates the defect.
Ultrasound image- A small cyst associated with the eyelid. By asking the patient to look left/right, it is seen to move freely and independently over the globe.
Lens Pathology
CATARACTS
- Is a progressive clouding of the crystalline lens of the eye.
- Ultrasound generally isnt used to examine cataracts but it is important to be familiar with their appearances, as they will be regularly encountered.
- The surgical treatment via a lens replacement is common in the western world. The normal appearances of a replaced lens must be familiarised so complications will be recognised.
Ultrasound image- Eye ultrasound comparing a cataract (left) and a normal lens
Ultrasound image- A developing cataract.
Ultrasound image- An artificial lens replacement.
Ultrasound image- A collapsed lens from an old penetrating injury.
SUBLUXED LENS
- Generally is traumatic or post surgical, but can be associated with some medical conditions such as Marfan’s syndrome.
Ultrasound image-A subluxed lens following complications from cataract surgery.
Ultrasound image-A dislocated lens.
Ultrasound image- A dislocated contact lens. This contact lens had been missing for almost 1 year.
Ultrasound image- A small shard adjacent to but not penetrating the cornea.
Ultrasound image- The foreign body (red arrow) showing a small hypoechoic reaction (green).
Ultrasound image- These cysts are usually asymptomatic and are often known to the referrer. However small peripheral ones may not have been clinically visible.
Ultrasound image- Iris cyst: Small isolated cysts may be seen in the anterior chamber on the iris or laterally at the ciliary bodies.
Vitreous Haemorrhage
- The vitreous humour is a colourless, gelatinous liquid filling the posterior chamber and giving the eye its shape. It is composed of 98% water. It also contains phagocytes which remove debris from the visual field. It is created by specific retinal cells, but not replenished so if significant material (haemorrhage) enters the vitreous it will remain there unless removed.
- The vitreous is attached anteriorly at the Ora Serrata with the retina. So vitreous detachment/haemorrhage will have a ‘V’ shape similar to a retinal detachment. The dynamics of ultrasound make it easy to tell the 2 apart. Get the patient to look from side to side as you scan, a vitreous detachment will lift off the posterior globe whilst a retinal detachment remains fixed at the optic disc.
- Vitreous will also deteriorate with age (liquefaction) and have swirling mobile debris visible.
Ultrasound image- Vitreous haemorrhage. High gain settings may be needed to adequately visualise the haemorrhage. Ask the patient to look left/right to see the haemorrhage move within the vitreous.
Ultrasound image- A chronic vitreous haemorrhage
Eye ultrasound of an acute on chronic vitreous haemorrhage.
Ultrasound image- The acute haemorrhage underlying the vitreous humor.
Ultrasound image- Use of color maps on B-mode may give additional information and detail.
Ultrasound image-The margin of a vitreous haemorrhage may have a detached irregular appearance.
Retinal Detachment
- A retinal detachment occurs when the retina lifts off the underlying choroid.
- The most common cause is due to a tear of the retina. Retinal tears occur when the vitreous lifts off the retina and an adherent portion tears the retina leaving a flap. Viteous humor or haemorrhage may then make it’s way under the retina.
Ultrasound appearances are a characteristic membranous ‘ V ‘ that remains fixed at the optic disc. If a retinal detachment is discovered early in it’s evolution it may only be one ‘arm’ of the ‘ V ‘.
Ultrasound image- Retinal detachment: Note the typical fixed ‘V’ pattern.
Imaging Post-Treatment of Retinal Detachment
Material is inserted into the globe to apply retinal tampinade.
- Scleral buckle and cryotherapy
- Vitrectomy
- Gas – Pneumatic retinopexy
- Silicone oil
Pneumatic or silicon oil retinopexy is often used in conjunction with vitrectomy.
Silicone oil is heavier and provides better pressure than the gas but has more associated complications including cataract, glaucoma and corneal opacification. (REF http://www.ncbi.nlm.nih.gov/pubmed/1762369 ).
Maintaining appropriate post operative head position is vital to the success of either treatment. The oil or gel must remain against the detachment.
Ultrasound image- Silicone gel in an eye to treat a retinal detachment.
Ultrasound image- Ultrasound of a ruptured globe containing air and silicone oil.
Ultrasound of an eye treated by pneumatic retinopexy.
Ultrasound of an eye treated by silicone oil and pneumatic retinopexy.
Choroidal Detachment
The choroid is the firm, vascular layer between the retina and the outer sclera.
In humans, it is rich in melanin giving it a dark colour. This controls unwanted reflection of light.
High melanin content also increases the risk of melanoma (see Choroidal melanoma)
Eye ultrasound of a choroidal detachment from one side of the globe.
Choroidal Melanoma
- The choroid is rich in melanin giving it a dark colour. This controls unwanted reflection of light. High melanin content also increases the risk of melanoma.
- Uveal Melanomas (comprising,the iris, ciliary bodies and choroid) are the most common eye malignancy.
Patients with small choroidal melanoma (< 4 mm thickness) develop metastasis in 16% of cases at 5 years follow up, whereas those with medium choroidal melanoma (4-8 mm thickness) and large choroidal melanoma (> 8 mm thickness) develop metastasis in 32 and 53%, respectively. The difficulty with early detection of choroidal melanoma relates to its clinical similarity to benign choroidal nevus. {REF:
“Clinical features of small choroidal melanoma.” Curr Opin Ophthalmol. 2002; 13(3):135-41 (ISSN: 1040-8738) }
Ultrasound image- Choroidal Melanoma. Importantly, note the thickness and distance from the optic nerve.
Ultrasound image- Increased vascularity adjacent to the choroidal melanoma.
Ultrasound image-The melanoma is evident postero-superiorly but cannot be viewed in detail. By asking the patient to ‘look-up’ the melanoma moves into a more accessible position (see zoomed image).
Ultrasound image- A large choroidal melanoma with an associated small retinal detachment.
Colour doppler ultrasound demonstrating flow in a choroidal melanoma.
Ultrasound image- A large eye mass abutting the lens.
Ultrasound image- A large eye melanoma with a retinal detachment and vitreaous haemorrhage.
Ultrasound of a large metastasis in the eye.
Choroiditis
Choroiditis (uveitis) is often related to auto-immune disease. If the retina is involved, it is ‘chorioretinitis.
Chroiditis with a small choroidal detachment posteriorly.
Choroidal Osteoma
- A rare benign tumour involving ossification of the choroid, particularly in the peri-papillary region.
- Unknown etiology
- Is often assymptomatic and affects otherwise healthy eys.
Choroidal Osteoma
Eye Osteoma
Chalazion
- A chronic sterile granuloma residing within the eyelid. If acute secondary infection (e.g. Staphylococcus aureus) takes place, the lesion is known as hordeolum.(1)
- Etiology: induced by retained sebaceous secretions from meibomian gland.
(1)REF: http://eyewiki.aao.org/Chalazion
Ultrasound image- A chalazion.
Ultrasound image- These will usually be clinically diagnosed and excised, however patients may be referred for assessment of a lump.
Staphyloma
- A staphyloma is the abnormal stretching of the uveal tissue.
- This can be anterior, equatorial or posterior.
- Anterior staphyloma’s are clinically evident by a characteristic black protrusion under the eyelid (black due to the melanoma rich uvea/choroid).
- Ultrasound may be used to confirm posterior staphyloma’s
Ultrasound appearances are of deformity or distortion of the normally smoothly rounded posterior globe.
Ultrasound image-The extended Anterior-posterior eye length can cause near-sightedness.
Ultrasound image-Bilateral staphyloma’s.
Foreign Body
Ultrasound image-The normal appearance of a contact lens.
Ultrasound image-A contact lens displaced, misplaced high under the tarsal plate.
Ultrasound image-A small echogenic foreign body with adjacent fluid. Markedly increased vascularity seen with power doppler confirming acute inflammatory change.
Optic Disc and Optic Nerve Abnormalities
Ultrasound image-Papilledema suggests raised intracranial pressure.