Special senses Flashcards
development of the ocular globe in carnivores continues after birth until
5-6 weeks
what does the eye develop from
outpouching of the brain
The three layers of the ocular globe are
outer/fibrous (sclera, cornea)
middle/uvea (iris, ciliary body, choroid with tapetum lucidum)
inner/nervous (retina)
What are the three chambers of the eye
anterior, posterior (both have aqueous humor) and vitreous (Gives the globe its shape)
Purpose of the eye
gather and permit entry to photons of light -> absorbed by retina to convert to electrical energy -> interpreted by the brain as sensory info
vision requires a ____ cornea, lens and humors
clear. anything that changes clarity impairs vision
What contributes to the adnexa of the eye
eyelids, conjunctiva, orbit. Important first line of protection
the eye has a ____ repertoire of responses, which means clinical exams while the patient is still living is super improtant
limited. Hard to determine inciting cause of eye problems post mortem
How does the clinical and pathological definition of uveitis differ
clinical - fibrin flare
pathological - inflammatory leukocytes in uvea
regeneration in the eye is ____
limited, except for the lens and cornea
Uveitis
Inflammation of the vascular layer/uvea
anterior uveitis vs panuveitis
Anterior uveitis = inflammation of the iris and ciliary body
* Panuveitis = inflammation of all 3 parts, iris, ciliary body and choroid
ophalmitis
Endophthalmitis = inflammation of the uvea and three ocular chambers
(anterior, posterior and vitreous)
Panophthalmitis = endophthalmitis + inflammation of the sclera
hypopyon
accumulation of neutrophils and fibrin that settles ventrally in the anterior chamber
hyphema
accumulation of blood in the anterior chamber
phthisis bulbi
end stage eye, atrophy, collapse, fibrosis
What is not present in the cornea?
blood vessels and pigment -> these would obstruct light
Largest component of the cornea
stroma -> dehydrated parallel bundles of collagen and rare keratinocytes
What are types of damage that can occur to the cornea
dessication, trauma, chemical injury
defenses of teh cornea
Tears, blinking, which have small numbers of leukocyets
keratitis
inflammation of the corena
neovascularization
new blood vessels grow from limbus into cornea
what are the two most common causes of corneal damage
trauma, dessication
causes of desiccation
breed related exophthalmos (protruding eyes in brachys)
defective eyelids structure or function
acquired ocular enlargement such as glaucoma
chronic keratitis
corneal response to injury. Abnormal tear film or mechanical injury leads to chronic corneal irritation, leading to metaplasia. Cornea becomes skin like
Superficial corneal ulcers
corneal edema with epithelial regeneration which covers the defect. Heals rapidly
Indolent ulcer
failure of normal ulcer healing with no underlying specific cause.
indolent ulcers are most common in what species
dogs
in indolent ulcers, the newly formed epithelium fails to adhere to the______
underlying stroma, and a cleft forms
Melting ulcer/ keratomalacia
ulceration leads to a release in lytic enzymes from neutrophils and/or pathogens, leading to stromal malacia/necrosis
Keratomalacia can involve what pathogens?
Fungal (keratomycosis) or bacterial
Descemetocele
deep ulcer that reaches descemets membrane
corneal sequestrum is most common in what species
cats
corneal sequestrums occur secondary to
chronic ulceration
Sequelae of corneal ulcers
- healing
- Indolent ulcers
- Melting ulcers
- Descemetocele
- Corneal sequestrum
- Perforation & Iris Prolapse
- phthisis bulbi
keratoconjunctivitis sicca (KCS)
Immune-mediated lacrimal adenitis (main cause) → ↓ tear film → desiccation → KCS
KCS is most common in
dogs
Dermoid
developmental abnormality due to ectopic hair follicles and adnexal glands
Infectious bovine keratoconjunctivitis (PINK EYE) caused by
Moraxella bovis
Infectious Bovine Keratoconjunctivitis Aka Pink Eye: more severe in calves or adults?
calves
Herpesvirus Keratitis
caused by FHV-1, usually a disease of kittens
Eosinophilic keratitis is most common in what species
cats >horses
gross features of eosinophilic keratitis
white to pink plaques on the cornea/ conjunctiva
Chronic superficial keratits affects which specific breeds?
German shepherds and sighthounds
What causes chornic superficial keratitis
immune-mediated disease targeting altered antigen of the cornea
Melanocytic neoplasia
darkly pigmented neoplasia derived from melanocytes of the limbus
