Eye Flashcards by Gwen Gross

What are the 5 compartments of the eye?

Eyelids/Conjunctiva Cornea Uvea (iris, ciliary body, retina) Lens Retina and Vitreous

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What are 3 circulatory disorders of the eye?

Corneal Edema Hyphema Glaucoma

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What ocular disorder is observed in this puppy?

Corneal Edema

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What are the 2 common causes of corneal opacity?

Corneal edema and corneal deposits

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What are the 3 causes of corneal edema?

Injury to epithelium (ulceration)

Injury to endothelium: corneal endothelial dystrophy, increased IOP (glaucoma), immune-mediated

Keratitis: neovascularization w/ leaky capillaries

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What is causing corneal edema in this patient and what diagnostic test has been performed?

A corneal ulcer is causing edema in this patient and it is confirmed with a fluorescein stain when the stain is taken up by the stroma.

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What mechanism of corneal edema involves inflammation and neovascularization from the limbus?

Keratitis

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What causes “blue eye” in puppies?

Immune mediated corneal edema.

Ag-Ab complexes deposited on Descemet’s membrane destroy its integrity.

Consequence of infection with Canine Adenovirus 1 (Canine Infectious Hepatitis)

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Pathogenesis of _____ _______ _____ involves inborn errors of metabolism and death of corneal endothelial cells.

Corneal endothelial dystrophy

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What are the features of Corneal Endothelial Dystrophy?

No inflammation

Bilaterally symmetrical

Begins laterally and becomes diffuse over the course of months

Breed predispositions!

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A patient presents with blood in the anterior chamber of the eye. What is the name of this disorder and where is the blood usually coming from?

Hyphema

Blood usually comes from the uvea or retina

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Hyphema can be primary or secondary. How can you tell the difference?

Physical exam would show hemorrhage elsewhere in the body with secondary hyphema.

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Serious consequences of hyphema include:

Blindness: due to physical vision obstruction, or retinal detachment

Filtration angle can be affected and lack of drainage can cause glaucoma.

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What are 4 potential causes of hyphema?

Trauma

Clotting disorders

Vasculitis (inc permeability due to inflammation: common in cats with FIP)

Severe hypertension (cats with renal disease or hyperthyroidism)

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A dog with painful, large eyes presents to your clinic. What disorder do you suspect and what tests could you use to confirm?

Glaucoma

IO pressure test

R/O neoplasia behind the eye by gently pushing on the eye to see if it moves backward

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Features of glaucoma on opthalmic exam:

Large, protruding eyes. Sclera visible all the way around.

Loss of iris margins due to corneal edema

Engorged scleral vessels

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Blepharospasm:

Eyelid spasm/squinting

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Epiphora:

tear production

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Bupthalmia:

Big eye

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Goniodysgenesis (malformation of the trabecular meshwork) causes what type of inherited glaucoma in dogs?

Primary glaucoma: due to abnormal filtration angle

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Secondary glaucoma is the most common type and can be caused by anything that obstructs drainage of the aqueous humor, including:

Exudate (endophtalmitis)

Lens luxation

Posterior synechia (iris adheres to lens)

Peripheral anterior synechia (iris adheres to cornea)

Compression of the filtration angle

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Optic nerve atrophy, lens luxation, cataracts, iris atrophy, and retinal degeneration and atrophy are consequences of:

Glaucoma

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A 12 year old Cocker Spaniel with no previous history of ocular disease presents to your clinic with a bulging, enlarged left eye. The sclera is visible all the way around and the scleral vessels are significantly enlarged. In addition, the lens is displaced. What could have caused the lens to shift in position?

Lens luxation is a consequence of glaucoma, caused by disruption and stretching of the zonular fibers that normally hold the lens in place

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Bingo is having trouble seeing in his old age. Upon examination of the left eye, you note a marked opacity, yet you can see the iris all the way around, which tells you this is affecting the lens and not the cornea. What is this disorder and mechanism?

Cataracts

Swelling/degeneration of the lenticular fibers leads to opacity. This is the most common disease of the lens.

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How does the lens respond to injury?

Swelling of injured fibers \> fiber fragmentation and disintegration Hyperplasia and fibrous metaplasia of the lens epithelium Posterior lens epithelial migration Shrinkng and wrinkling of the lens capsule. Mineralization.

Which of the following will result in a cataract? Radiation Increased IOP Endopthalmitis Diabetes mellitus Trauma

ALL will result in a cataract

The lens on a 15 year old dog is tinted blue, and the dog still seems to be able to see. Is this a cataract?

No. This is lenticular sclerosis, and is a normal senile change.

An 8 year old pomeranian comes in for apparent blindness. She's exhibiting extreme mydriasis and has no PLR. You perform a fundic exam and determine the cause to be retinal degeneration and atrophy. What underlying causes could be on the differential?

Senile change Inherited metabolic defect of photoreceptor cells (progressive retinal atrophy) Toxicity (kills retinal neurons) Metabolic deficiencies (taurine, vit A) Increased IOP Retinal detachment

Retinal detachment occurs between the neural and pigmented layers, and leads to retinal degeneration and atrophy. What can cause retinal detachment?

INFLAMMATION choroiditis, retinitis hemorrhage neoplasm trauma

A cat presents to your clinic with ocular swelling and edema, discharge, chemosis, and hyperemia. What can be causing conjunctivitis in this cat?

Feline Herpesvirus 1 Chlamydiophilia felis Mycoplasma felis (normal resident)

You arrive at a farm to see that a horse's eye has chemosis, corneal edema, and mucopurulent exudate. You would like to stain the eye to look for keratitis, but the owner is refusing treatment. A few days later the owner calls back because the eye now has a melting ulcer (keratomalacia) . What is the likely cause?

Bacterial infection. Necrosis of corneal epithelium and stroma due to neutrophilic enzymes. \*Pseudomonas aeruginosa

What's wrong with this cow's eye and what is the primary pathogen?

Infectious keratoconjuntivitis caused by Moraxella bovis

Keratitis can be caused by:

Trauma Bacterial (M. bovis, Pseudomonas) Chlamydia/Mycoplasma Viruses (IBR, MCF, FHV-1) Fungi (Aspergillosis, Mucormycosis) Drying and dessication Idiopathic

What are the 3 idiopathic instances of keratitis in small animals?

Chronic superficial keratitis (Pannus) in German Shepherds Superficial indolent ulcers in Boxers Feline eosinophilic keratitis

The horse with the melting ulcer has been on antibiotics for a few days, and is now presenting with this lesion. What is this and what is your next step?

Descmetocele. Cornea; degeneration has reached all the way down to Descmet's membrane, the last line of defense before corneal rupture. Your next step is ER referral to a specialist.

What are some consequences of corneal perforation?

Phthisis bulbi Descmetocele Anterior senechia Shrinking of the anterior chamber

This characteristic black lesion on the cornea is caused by localized necrosis of the epithelium and anterior stroma. What is it and why does this cat likely have it?

Corneal sequestrum Caused by severe corneal trauma or FHV

Tutu comes into your clinic with mucopurulent exudate coming from her right eye. You perform a shirmer tear test and diagnose Tutu with keratoconjunctivitis sicca, or dry eye. What causes this condition?

Lacrimal gland injury Immune-mediated injury to lacrimal glands \> decreased tears \> dried out cornea/conjunctiva \> chronic irritation

What is blepharospasm?

Inadvertant closing of the eyelids. Squinting.

When there is exudate settling in the anterior chamber of the eye (hypopyon), what is the most appropriate morphological diagnosis? What disease can cause uveitis in this cat?

Anterior uveitis Can indicate FIP in cats

Feline idiopathic lymphoplasmacytic uveitis, equine recurrent uveitis, and other systemic diseases, can cause uveitis by what mechanism?

Hypersensitivity

What are the infectious causes of uveitis?

Systemic disease with uvea affected (FIP, mycoses) Perforating corneal ulcers Penetrating injuries

An inflammatory response to lens protein can cause uveitis. What are the 2 lens-induced uveitis mechanisms?

Phacolytic: leakage of lens protein from a hypermature cataract Phacoclastic: lens rupture (more severe)

Keratic precipitates are a good indicator of:

uveitis

A cat comes in with keratic precipitates and dyscoria, and you suspect anterior uveitis. What could be causing the irregular shape of the iris?

Posterior synechia: attachment of the iris to the lens.

Consequences of uveitis:

Synechia Preiridal fibrovascular membrane (PIFM) Cataracts Lens luxation Glaucoma Retinal detachment Phthisis bulbi

What is the most common cause of blindness in horses, ponies, and mules?

Equine Recurrent Uveitis (periodic opthalmia, moon blindness, iridocyclitis)

You are called to a farm where a horse is suddenly unable to see and has an opacity over its eye as shown. What disorder is this and what should you be testing for as a potential cause?

Moonblindness or Equine Recurrent Uveitis Test for Leptospirosis interrogans serovars, as moon blindness is from a hypersensitivity to previous infection.

Retinitis is usually an extension from _______ or \_\_\_\_\_\_\_.

Choroiditis; Encephalitis

What are some infectious causes of retinitis?

Neurotropic viral infections (RV, Pseudorabies, Distemper) Visceral Larval Migrans (Baylisascaris procyonis or Toxocara canis)

You arrive at a farm to find several lambs with synopthalmos. What is the likely cause?

Ingestion of Veratrum californicum at day 14 gestation. Incomplete separation of the orbits during embryogenesis.

In utero infection of BVDV, bluetongue, border disease, akabane, panleukopenia, and classical swine fever is known to cause what?

Developmental anomalies

Although this developmental anomaly can be inherited, what should be on your differential for this cow?

In utero infection with BVDV can cause micropthalmia in cattle.

This developmental anomaly features hair and skin growing over the surface of the eye:

Corneal dermoid

What can cause lens luxation?

Trauma Glaucoma Anterior Uveitis Inherited issue with zonular fibers that hold the lens in place

Histology on a dog with glaucoma. What is causing increased IOP in this patient?

Goniodysgenesis: malformation of the iridocorneal filtration angle

A family has just adopted a cat and has noticed an abnormality in his eye. They want to know how this could have happened and if the cat is blind. What do you tell them?

This is persistent pupillary membrane It happens during early development when the vascular tunic that supplies the lens fails to regress. The cat was born with this anomaly and its vision is not obstructed.

What the heck is going on with this dog's eye?

Iris hypoplasia

A breeder brings a couple of her 5 week old Collie puppies in because they have notch-like defects in their irises. She's worried that her son may have damaged their eyes while playing with them. What can you tell her to reassure her?

This is an iris coloboma and the puppies were born this way (defective closure of the embryonic fissure of the eye). Collies are predisposed to this condition. Colobomas can occur after birth in some dogs, as a result of glaucoma.

The Collie breeder is back for genetic testing and fundic exams on her new breeding stock! She's interested in testing for Collie Eye Anomaly before breeding the dogs. What would you expect to find on fundic exam in dogs with scleral ectasia?

Tortuous retinal vessels Focal to diffuse choroidal and tapetal hypoplasia Optic nerve coloboma (choroid ballooning into the optic nerve) Retinal separation with intraocular hemorrhage

In a Collie with scleral ectasia, would you expect to find signs in one or both eyes?

BOTH. Always bilateral.

What is this disease of animals born with visual defects?

Retinal dysplasia

Besides being an inherited condition, what are some other causes of retinal dysplasia?

Retinal injuries in the embryonic eye: BVDV Bluetongue Parvo Panleuk

Zipper the cat comes in for an eye exam. The owner states that her eye used to be all yellow, but these freckles have been growing larger over the past couple months. Upon looking at the eye, you note that the lesions look raised, and have a velvety texture. What disease does Zipper have?

Feline diffuse iris melanoma. The most common intra-ocular neoplasm in cats. Most are malignant.

What is the best treatment for Zipper, the cat with feline diffuse iris melanoma?

Enucleation. Although the rate of matastasis is low, the chance of ZIpper having glaucoma is very high.

What is the most common intra-ocular neoplasm in dogs and other species?

Uveal melanoma \*usually benign in dogs, but will still cause physical damage like glaucoma and retinal detachment.

This canine melanoma of the conjunctiva is most likely (benign/malignant)?

Malignant \*canine melanomas of haired skin of the eyelid are benign

What are the most important prognostic factors for melanocytic neoplasms?

Species and location

A client brings in his dog for a suspected eye infection, and upon examination you see discrete nodules in the posterior cavity of the eye. What are you most worried about in this situation?

Glaucoma and retinal detachment This is most likely a cilliary adenoma. Most of these cilliary neoplasms in dogs are benign, and even the malignant carcinomas act benign. Glaucoma is likely with this tumor because it can easily smash the filtration angle.

This neoplasm of cats arises after ocular trauma, and is always malignant. Why is the prognosis poor even with enucleation?

Intraocular sarcomas feature widespread invasion throughout the eye and down the optic nerve, allowing distance metastasis to occur following enucleation.

Uveal lymphoma is the most common metastasis involving the eye, especially in cats. How can you distinguish it from anterior uveitis?

Change in the color/shape of the iris (thickening/pallor)

What causes grey eye in chickens?

Marek's disease (Gallid herpesvirus 2)

What dat?

Meibomian adenoma

White cats and Hereford cows. What dat?

Squame

You notice this frosty, crystalline looking spot on a dog's eye. What other condition do you suspect this dog might have?

Hyperlipidemia This is corneal lipidosis, and although it can be idiopathic, it is associated with hyperlipidemia and certain breed predispositions.

What is the cause of Tropical Keratopathy (Florida Spots) in cats?

Anterior stromal collagen disorder with various degrees of epithelial hyperplasia.

What are the causes of corneal pigmentation in each of these cases?

A: Corneal sequestrum B: Entrapped uvea (iris entrapped in cornea) C: Melanin in response to injury (chronic keratitis)