Eye Flashcards
What are the 5 compartments of the eye?
Eyelids/Conjunctiva Cornea Uvea (iris, ciliary body, retina) Lens Retina and Vitreous
What are 3 circulatory disorders of the eye?
Corneal Edema Hyphema Glaucoma
What ocular disorder is observed in this puppy?
Corneal Edema
What are the 2 common causes of corneal opacity?
Corneal edema and corneal deposits
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
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.
What mechanism of corneal edema involves inflammation and neovascularization from the limbus?
Keratitis
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)
Pathogenesis of _____ _______ _____ involves inborn errors of metabolism and death of corneal endothelial cells.
Corneal endothelial dystrophy
What are the features of Corneal Endothelial Dystrophy?
No inflammation
Bilaterally symmetrical
Begins laterally and becomes diffuse over the course of months
Breed predispositions!
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
Hyphema can be primary or secondary. How can you tell the difference?
Physical exam would show hemorrhage elsewhere in the body with secondary hyphema.
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.
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)
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
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
Blepharospasm:
Eyelid spasm/squinting
Epiphora:
tear production
Bupthalmia:
Big eye
Goniodysgenesis (malformation of the trabecular meshwork) causes what type of inherited glaucoma in dogs?
Primary glaucoma: due to abnormal filtration angle
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
Optic nerve atrophy, lens luxation, cataracts, iris atrophy, and retinal degeneration and atrophy are consequences of:
Glaucoma
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
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.
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
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.
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
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
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.
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.
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
What is this disease of animals born with visual defects?
Retinal dysplasia
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.
This canine melanoma of the conjunctiva is most likely (benign/malignant)?
Malignant
*canine melanomas of haired skin of the eyelid are benign
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.
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)
