Eye Anatomy Flashcards
What is the pupil?
Opening which allows light to reach retina
Surrounded by iris
What is the ciliary body?
The muscle that changes the shape of the lens
What is the function of the cornea, lens and anterior chamber?
Refract light
What is the suspensory ligament?
Holds the lens of the eye in place
What is the sclera? What does it do?
The white of the eyeball
Provides support
WHat is the choroid?
A vascular layer in between the retina and sclera
Contains connective tissue
What is the fovea centralis?
The point on the retina where visual acuity is highest
No blood vessels
What is the optic disc?
The blind spot - where ganglia leave the retina
No photoreceptors
What is the tapetum lucidum?
Triangular area below optic nerve
Between retina and choroid
Contains reflective iridescent cells containing crystals
What is the ora serrata?
Where photoreceptors end (end of retina)
WHat is the limbus?
The transition between the cornea and sclera
How are images formed? (3 processes)
Refraction of light
Accommodation of pupil
Constriction of pupil
What is accomodation when image forming?
Distance vision - lens flat, lens fibres taught, ciliary muscles relaxed
Close up - lens round, lens fibres relaxed, ciliary muscles contract
How is aqueous humor formed?
By the ciliary processes filtering blood plasma
How is aqueous humour drained?
Fluid leaks from posterior to anterior chamber, then returns to the circulatory system at the limbus
When doing the pupillary light reflex, which muscles constrict and dilate the pupil?
Circular muscles construct
Radial muscles dilate
What is strabismus?
Abnormal eye position
What are the 3 types of strabismus? Which cranial nerve causes this?
Medial (CN VI)
Ventrolateral (CN III)
Extorsional (CN IV)
What layers make up the retina?
Uvea (vascular layer)
Fibrous layer
What are the layers & cells of the retina from the outside in?
Pigmented epithelial cells
Photoreceptors
Bipolar neutrons
Ganglia to optic nerve
What do rods/cones each detect?
Rods black and white, low light, high acuity
Cones trichrome, bright light, low acuity
Describe the development of the eye?
Optic groove develops from forefront
Optic groove surrounded by choroid fissure
Fissures fuse to form the optic cup
What is progressive retinal atrophy? WHich species is it common in?
Night blindness
Red setter, Abyssinian/Siamese cat
Blood vessels waste away, pupils dilate to compensate
What is a detached retina?
Nervous part of retina detaches from pigmented layer at optic canal
Retina is deprived of O2 and nutrients
What is cataract?
Cloudy lens due to age, diabetes and genetics
Can be accompanied by lens luxurious
Lens replacement
What is glaucoma?
Increased intraoccular pressure
Pain and blindness
Treat with drugs, improve drainage/reduce humor secretion
In cats, what can glaucoma be a symptom of?
Chronic renal failure
What is keratoconjunctivitis sicca?
Dry eye
Autoimmune disease - failure to produce lacrimal fluid
Treat with artificial tears
What is corneal ulceration? Why can corneas be easily transplanted?
Wounds that leaves scars and impair vision
No blood vessels, no immune response
What is conjuctivitis?
Inflammation of conjuctiva
