Opthalmology Flashcards
What are the 2 groups of tissues in the eye?
Adnexa and Globe
Define adnexa
Group of tissues around the eye (protect, support, and assist function of globe
What coordinates the eye movements?
Medial Longitudinal Fasciculus (CNS)
Describe the innervation of extra ocular muscles of the eye
Antagonistic muscles have reciprocal innervation
What muscles are innervated by CN III?
Dorsal, Medial, Ventral Rectus + Ventral oblique
The dorsal oblique is innervated by CN _______
IV
Which CN innervates the Lat Rectus?
VI
Which muscle forms a cone that envelopes and retracts the globe into the orbit, is absent in primates/birds/snakes and is innervated by CN VI?
Retractor bulbi
What protects the surface of the globe and spreads tears throughout the cornea?
Eyelids
What reflexes facilitate eyelid closure?
Corneal, Palpebral, Dazzle
Subcortical reflex means it is processed in which part of the brain?
Midbrain
Which glands line the lid margin?
Meibomian glands
Which eyelid is most mobile in avian and reptile species?
Lower
What is the term for eyelids sealed at birth?
Physiologic Ankyloblepahron
When do eyelids begin to open postpartum?
10-14 days
What lines the outer and inner surface of the TE?
Conjuctiva
Where is the TE located in domestic species?
Ventromedial
What is the outer oily layer produced by meibomian glands?
Precorneal tear film
List 3 functions of the tear film?
Hydration
Lubrication
Oxygen and nutritional support
What is the medical term for dry eye?
Keratoconjuctivitis sicca
List the clinical signs of dry eye
Mucupurulent ocular discharge, dry corneal surface
What is the outer/fibrous coat of the eye composed of ?
Cornea, sclera, limbus
How does the cornea stay clear?
Lack of vessels and pigment and non-keratinized epithelium
How are the corneal stroma collagen fibrils organized?
Lattice-like and equidistant to permit light transmission
Describe the cornea layers
Epithelium - strat squamous/hydrophobic
Stroma - hydrophilic can uptake fluorescein
What is another name for the corneal endothelium?
Descemet’s membrane
If there is loss of protection against Stroma hydration, what happens?
Corneal edema
Why are corneal ulcers so painful?
Cornea is highly innervated
List some clinical signs of ocular pain
- blepharospasm
- epiphora
- TE Elevation
The afferent aspect of the blink reflex is by which branch of CN V?
Opthalmic (V1)
What is the efferent innervation to the blink reflex?
Facial n
List the portions of the anterior urea
Iris and ciliary body
What is the shape of the pupil dependent on?
Predator vs prey species
What structure is most common in herbivore’s anterior uvea?
Granula Iridica - corporta nigra
Which muscle constricts the pupil?
Sphincter - parasympathetic
What muscle opens the pupil?
Dilator - sympathetic
Mydriasis =
dilation
Myosis =
Constriction
Why do animals have pupils of different shapes?
To direct light to the retina area with the most photoreceptors
What are the 2 parts of ciliary body?
Pars plicata and plana
Which part of the ciliary body contains the ciliary processes?
pars plicata
Describe the function of the ciliary body
Produce aqueous humor and origin of zonular fibers to keep lens in place
Where is the aqueous humor?
Anterior and posterior chamber
The intraocular pressure of the eye depends on :
Amount of aqueous humor in the eye
Describe fluid pathway in the eye
Must flow through the pupil to reach anterior chamber after being made
Define glaucoma
High pressure in the eye
Describe the anatomy of the lens
- avascular
- biconvex
Lens function:
Light focus into retina
The points where the lens fibers attach to one another:
Suture lines
What is the refractive power of the lens impacted by?
Refractive index and curvature
What originates from the ciliary body that accommodate the lens?
Zonular fibers
An aphakic crescent can be a sign of?
Lens subluxation - area of pupil zone not filled by lens
When the lens is no longer attached and may move around the chamber?
Lens luxation
The lens accommodate to do what?
Bring image into focus
How can accommodation occur?
- changing the curvature or position of lens (symp - distance ; close - parasympathetic)
If the ciliary muscles contract, what happens to the lens?
It becomes more rounded - zonular fibers relax
What is the transparent, gelatinous material attached to the back of the eye?
Vitreous
What is vitreous composed of?
Water, collagen, hyaluronic acid
If you have floaters, what is that a sign of?
Degeneration of the vitreous
How many layers does the retina have?
10
What does the tapetum do?
Acts like mirror to reflect light
Where is the lucidum/ what is it part of?
Choroid
Rods are responsible for ?
Night vision - black and white
Cones are responsible for what ?
Day vision and color
