Ocular (new book)

Question 1

Overall, a healthy eye appears as an oval image with four clear hyperechoic structures. Moving from the anterior to the posterior they are?

Answer 1

the cornea, iris, pos- terior crystalline capsule, and the retina/choroid/ sclera complex, which physiologically cannot be detected separately on US images.

Question 2

How does the normal cornea appear and what is its thickness?

Answer 2

The cornea appears as a fine, regular curvilinear hyperechoic line (corneal epithelium), an anechoic area (corneal stroma), and an unbroken, 2.33 ± 0.39 mm thick, hyperechoic line which should not vary in the entire cornea (corneal endothelium).

Question 3

How can corpora negra or iris cysts be differentiated?

Answer 3

Cysts have an anechoic content.

Question 4

The crystalline is another term for the what?

Answer 4

Lens

Question 5

Lens dimensions are approximately what?

Answer 5

antero-posterior 12mm; diameter about 20 mm

Question 6

Changes in echogenicity of the vitreous can indicate?

Answer 6

Extraneous material (blood due to trauma, fibrin due to infection or inflammation, vitreous degrada- tion, asteroid hyalosis, lipid and calcium-contain- ing spheres that are visualized as echoic granules).
Change in echoic status (e.g., due to uveitis)

Question 7

Is an US indicated in cases of corneal US

Answer 7

No, although it may be helpful if severe eyelid oedema prevents direct eye examination.

Question 8

Anterior synechia are likely secondary to… and posterior are likely secondary to …..?

Answer 8

corneal perforation/ abscess and chronic uveitis.

Question 9

What is the posterior chamber?

Answer 9

Between the iris and the lens.

Question 10

What is the most common cause of equine blindness?

Answer 10

Uveitis, the most common cause of equine blindness, is an inflammation of the iris and/or the ciliary body due to systemic disease or directly to other eye disease.

Question 11

What are some of the US features of uveitis?

Answer 11

Clinical features include anterior chamber distension and some or all of the following signs that are detected by US:
● Eyelid or corneal edema
● Conjunctival hyperemia
● Acqueous humor opacity due to the presence of
inflammatory cells, fibrin, and blood (ifema)
● Miosis
● Darker, opaque, and swollen iris
● Anterior or posterior synechiae
● Crystalline opacity and cataract
● Crystalline sub-luxation or dislocation
● Vitreous apacity or degradation opacità
● Fundus oculi abnormalities

Question 12

What is an iris prolapse

Answer 12

Iris prolapse is usually caused by trauma or corneal wound and the iris protrudes through the wound. It is often associated with fibrin, blood (ifema), and/or pus (ipopion) deposits in the anterior chamber. The standard eye examination cannot be performed because of the accumulates in the anterior chamber, inflammation, and miosis.

Question 13

Glaucoma in the horse is frequently secondary to?

Answer 13

Uveitis, trauma, intra-ocular growths, blood (ifema), chronic intra-ocular inflam- mation, anterior lens dislocation, and any other agent that causes an imbalance in acqueous humor produc- tion and elimination.

Question 14

What is aphakia and microphakia?

Answer 14

congenitally absent or small lens.

Question 15

What holds the lens in position

Answer 15

Zonular strands

Question 16

Vitreous inflammation is often associated with?

Answer 16

uveitis

Question 17

Asteroid hyalosis is?

Answer 17

observed in some cases, is not usually of clinical importance. Usually constituted of calcium phosphate crystals, it appears as free, highly reflective, and hyperechoic on the EOUS

Question 18

Complete retinal detachment has a characteristic appearance but partial detachment can have other differentials such as?

Answer 18

Partial retina detachment appears as a hyperechoic convex line which should not be confused with other hyperechoic findings in the vitreous chamber like pseudomembrane or fibrin filaments

Question 19

What is important to assess with a suspected retinal detachment?

Answer 19

Assessing the area below the detached retina is cru- cial. If it is anechoic, it indicates a fluid-like ooze which might be reabsorbed. Echoic material suggests hemorrhage, neoplastic infiltrates, or inflammatory cells may be present.

Question 20

What is the most common intraocular tumour?

Answer 20

Melanoma, particularly of the iris.

Question 21

What are the most common retrobulbar neoplasms?

Answer 21

optic nerve medullo-epitelioma, hemangioma, fibroma, microglioma, granulocyte, sarcoma, lipoma, adenocarcinoma, lymphosarcoma, multilo- bar osteoma, and melanoma.

Question 22

What is a Baum’s bump artefact?

Answer 22

observed in a B-mode scan, create the illusion of an uprising Fundus oculi. They develop when the ultrasounds are refracted quickly from the center of the lens toward its periphery.

Question 23

What is shown in image A?

Answer 23

Corneal oedema

Question 24

What is shown in this image?

Answer 24

Stroma abscess

Question 25

What is shown in these images?

Answer 25

Perforated corneal ulcer and iris prolapse.

Question 26

A is the abnormal eye, what is shown?

Answer 26

Anterior uveitis. This image is from an 8-year-old paint mare with unilateral anterior uveitis. These images are a comparison of a normal eye (B) and an eye with uveitis (A and C). Hypoechoic material is within the posterior chambers (blue arrows) in the horse with uveitis. The hypoechoic material within the posterior chamber is inflammatory debris, probably fibrin or vitreous degeneration, that is typical in anterior uveitis. The lens is normal in position and shows no signs of cataracts. The cornea is irregular as evidenced in the yellow rectangle. These are typical signs of keratitis and anterior uveitis. 1: Cornea; 2: Iris; 3: Posterior lens capsule; 4: Corpora nigra.