SAM3.1: Optho Orbit

Microphthalmos

Congenitally small globe +/- abnormalities.

Microphthalmos must be differentiated from

phthisis bulbi.

True microphthalmos is association

without other ocular defects (cataracts, anterior segment dysgenesis, PHPV, retinal dysplasia).

Vision w/ microphthalmos

May or may not be present

Toxic microphthalmos

Pigs: Vitamin A deficient dams.

Griseofulvin pregnant queen (not a pig... it's a cat).

Genetic risk of microphthalmos in some spp/breeds includes

Merle ocular dysgenesis - homozygous for merle gene.

Throughbreds.

Exophthalmos

An eye that is more prominent or push forward w/in orbit.

Symptoms of exophthalmos (6)

Prominent (not enlarged) globes.

Difficult to retropulse.

Conjunctival hyperemia/chemosis.

Possible PO cavity lesions.

Elevated third eyelid.

+/- ocular discharge.

Dx for exopthalmos (6)

Palpation of the orbit/oral exam.

Chest rads and bloodwork.

Skull/dental rads.

FNA for cytology/biopsy.

U/S.

CT/MRI.

Palpation of the orbit/oral exam includes (2)

Retropulsion of the globe.

Examine PO cavity at the end of the exam (b/c it can be painful)

Chest rads and bloodwork should be done to

r/o disseminated neoplasia/infectious.

2 most common causes of exophthalmos are

masses or infections/inflammatory processes.

Etiology of Exophthalmos (12)

Retrobulbar cellulitis/abscess.

Neoplasia.

Crypto.

Eosinophilic myositis of masticatory mm.

Extraocular polymyositis.

Craniomandibular Osteopathy.

Cysts.

Hemorrhage.

Orbital fxs.

Vascular Anomalies.

Granulomas.

Tetanus.

What may you see in a P' w/ retrobulbar cellulitis/abscess

anorectic and/or febrile.

elevated WBCs.

involve FB.

involve teeth/SG.

Retrobulbar cellulitis/abscess is usually

very painful.

Tx for retrobulbar abscess

Drain.

C&S.

Appropriate ABX.

compresses.

Anti-inflam.

Remove FB/tooth.

Most common etiology of exophthalmos

Neoplasia (generally older P's)

Neoplasia pain in the eye

usually painless and slowly progressive.

What may you see with exophthalmos (2)

globe depressed by mass.

Secondary inflam can develop.

Trend for ocular neoplasia

usually primary tumors and malignant.

Ddx for primary retrobulbar tumors

multilobular osteoma,

fibrosarcoma,

meningioma,

adenocarcinoma,

SCC,

myxoma

Ddx for secondary retrobulbar tumors

metastatic,

adenocarcinoma from nasal cavity,

lymphosarcoma

Pseudotumor

a retrobulbar tumor that is a quasi-inflammatory process (not lymphoma)

Tx for retrobulbar tumors

Chemotherapy (LSA)

Radiation therapy (may damage lens, retina, lacrimal tissue)

Surgical excision (orbiotomy, may only be palliative)

Exenteration of orbit

Eosinophilic myositis of masticatory muscles signalment

bilateral, young dog

GSD

Eosinophilic myositis of masticatory muscles effect on eye

exophthalmos (during inflammation),

may cause muscle atrophy/fibrosis and enophthalmos

Etiology of eosinophilic myositis of masticatory muscles

immune-mediated

Dx of eosinophilic myositis of masticatory muscles

Bx of temporal m, submit to specialized lab

May see eosinophilia

Tx of eosinophilic myositis of masticatory muscles

immunosuppressive medications

Extraocular polymyositis signalment

bilateral, usually young, large breed dog

golden retriever may be predisposed

Extraocular polymyositis effect on eye

exophthalmos

T or F? Extraocular polymyositis is associated with thyroid hormone

False. NOT assoc with thryoid hormone, not like Grave’s disease in people

Tx of extraocular polymyositis

immunosuppressive medication (e.g. prednisone)

Craniomandibular osteopathy signalment

usually 3-6mo old,

scottish terrior/WHWT predisposed

Craniomandibular osteopathy etiology

self-limiting, non-neoplastic proliferative bone disease

What condition must be differentiated from exopthalmos

buphthalmos

Buphthalmos is

enlarged eye

How do you differentiate Buphthalmos and Exophthalmos

Buphthalmos eyes usually appear to have abnormalities.

Exophthalmos eyes are healthy eyes that look displaced.

Enophthalmos is

decreased volume of orbital contents - globe sunk into orbit.

Etiologies of Enophthalmos (6)

Pain.

Atrophy of the retrobulbar fat or m. tissue.

Dehydration.

Horner's syndrome.

Phthisis bulbi/microphthalmia.

Skull Fx.

Proptosis def

Forward displacement of the globe. Lid margins are behind globe equators.

proptosis is differentiated from

exophthalmos - lid margins on surface of the globe.

Prognosis for Proptosis?

Grave for vision.

Proptosis is

an emergency

At risk breeds for proptosis

brachycephalic dogs

Proptosis Tx

Surgically replace globe or enucleate - cool compresses and may need lateral canthotomy

Post-op Rx for Proptosis (2)

Topical ABX (and atropine if ulceration).

Systemic ABX and anti-inflammatory.

Post-op Sx for Proptosis (2)

Remove sutures when swelling subsides.

Assess vision and viability of globe.

Describe prolapse retrobulbar fat

herniation of retrobulbar fat through Tenon’s capsule

usually dorsal-lateral and presents as conjunctival swelling

Phthisis Bulbi (3)

Globe is phthisical.

was normal at one point.

chronic, diffuse intraocular inflammation w/ contraction may result in shrunken, disorganized, or atrophic globe.

Phthisis Bulbi is usually

comfortable (globe can remain until it becomes painful)

Globe position: Exotropia

Wall eyes - lateral strabismus

Globe position: Esotropia

Cross eyed (Siamese cats)

Strabismus can be the result of (3)

m. imbalance.

n. dysfxn.

central lesion.

Surgeries invoving the opthoorbit (6)

enucleation

exenteration

orbital prothesis

intraocular prosthesis

obitotomy

extrascleral (shell) prosthesis

Enucleation def

Removal of the globe, third eyelid, lacrimal tissue and eyelid margins.

Enucleation is indicated for

blind/painful eyes or neoplasia

Enucleation techniques (2)

Subconjunctival approach.

Transpalpebral approach - harder to do and takes longer, but more ideal for containment of potential infection/neoplasia.

Post op warning to client for enucleation

blood from the nostril on the same side as the enucleated eye w/in a few days post-op is normal.

Complications of Enucleation (5)

Hemorrhage.

Pain.

Draining fistula or orbital swelling - retained lacrimal tissue.

Orbital infection (rare).

Orbital emphysema.

Orbital infections: You may not want to do enculeation

at the same time as dirty procedures (teeth and AG)

Exenteration def

Removal of globe and orbital contents (extraocular mm). Less cosmetic appearance.

Orbital Prothesis placement of (2)

trimmed silicone sphere into orbit to improve cosmetic appearance.

More difficult to perform after exenteration.

Intraocular Prothesis has (2)

more cosmetic appearance.

dark silicone sphere.

Intraocular prothesis will allow

globe to move normally, but cornea can still be injured.

Intraocular prothesis is not indicated for

infection/tumor.

Intraocular prothesis has

lengthy recovery.

More follow up.

Comfort procedures as options for blind and painful eyes

Enucleation.

Intraocular prosthesis (only if no infection/tumor)

Chemical ciliary body ablation.

Chemical ciliary body ablation is not for

feline patients.