Eye exam (Plummer) Flashcards
1
Q
Anatomy
A
- Outer vascular tunic
- cornea
- sclera
- limbus (where the cornea and sclera meet)
- Nasolacrimal duct
- Lacrimal glands (most dom species)
- orbital lacrimal gland
- third eyelid lacrimal gland
- Conjuctiva: thin vascular mucus membrane covering sclera
- Middle vascular tunic
- iris
- ciliary body: produces aqueous humor
- coroid: sits between retina and sclera
- Lens
- Neurosensory tunic
- retina
- Optic nerve
- Tapetum
2
Q
Anterior chamber
A
Fluid filled area between cornea and lens I think
3
Q
Cornea function
A
- Protection
- focusing power of eye
- refracts light
- like the gross focus on a microscope
4
Q
Lens function
A
- Accomodates (changes shape) to focus light onto the back of the eye
- Like the fine focus on a microscope
5
Q
Retina function
A
- Transduction of light stimulus via electrical signals
- stimulates photoreceptors
- rods and cones
- signal modified
- ganglion cell axons go towards the optic nerve, coalesce, leave through lamina fibrosa and turn into optic nerve behind the eye
- stimulates photoreceptors
6
Q
Optic nerve function
A
- Gathers info from retina and carries it to the brain
7
Q
Basic eye exam
A
- Take a proper history
- Observe animal in waiting/exam rooms
- Observe interactions with owner
- Outside to inside
- adnexa and symmetry
- Front to back
- Cornea
- Lens
- Retina
8
Q
Two main presenting complaints
A
- Visual deficits
- Painful eye
9
Q
Essentials for ophtho hx
A
- vision in light and dark?
- Nigh probs=> may be dz of rod photoreceptors
- Day probs=> may be dz of cones or axial cataract
- vision for stationary and/or moving objects?
- tennis ball?
- moving objects=>may be dz of peripheral oculur fundus
- stationary objects=>may be dz of central retina and ocular opacities w/in visual axis
- stairs?
- novel environments?
- acute or slowly progressing?
- trauma, systemic disease, drugs?
- clinical signs?
- other systemic signs? PU/PD?
- character if discharge?
- what meds have already been given?
10
Q
Basic instruments
A
- Focused light beam penlight
- Schirmer’s tear test strips
- Fluorescein
- ophthalmoscope
- direct/indirect + 20D lens
- 2-4x magnification
11
Q
Additional diagnostic equipment
A
- Culturettes
- Rose Bengal stain
- TOpical anesthetic
- Blades, glass slides
- take samples of cornea
- Catheters and syringe
- flush nasolacrimal duct
- Tonometer
- measure IOP
12
Q
Basic Eye exam
A
- pupillary light reflexes
- helps localize dz
- menace response, other estimates of vision
- shirmer’s tear test
- do this before you put stuff in eye (dye, anesthetics)
- C & S if indicated
- External eye exam with stains
- Tonometery
- before dilation
- ophthalmoscopy
- views back of eye, need to dilate
13
Q
Path of sensory info received by the eye
A
- Light focused on back of eye
- retina stimulated
- info travels from optic nerve (CN 2, afferent arm) to optic chiasm
- decussation at optic chiasm
- then transmitted to pretectal nucleus (CN 2 I think) and edinger westphal nucleus of CN 3
- signal transmitted back to eye via a motor response CN
14
Q
Light-induced Pupillary reflexes
A
- Not synonymous with vision
- subcortical reflex
- highly excited and aggressive dogs/cats
- have dilated pupils that respond poorly
- due to high levels endogenous circulating catecholamines
- have dilated pupils that respond poorly
- LA-need an assistant to check consensual response
- Swinging flashlight test
- dynamic contraction anisocoria
- Retinal and prechiasmal optic nerve diseases
15
Q
Vision/PLR rules of thumb
A
- visual with normal PLRs
- A-OK
- visual with absent PLRs
- efferent prob CN 3 or iris sphincter
- mechanical or pharmacological interference
- Blind with normal PLRs
- something obscuring vision
- cataract
- cortical dz
- somewhere behind reflex arc
- something obscuring vision
- Blind with absent PLRs
- retina
- optic n.
16
Q
Dazzle
(Photic Blink Reflex)
A
- Elicit by a beam of light at ocular fundus, observe a positive blink reflex
- subcortical reflex: rostral colliculi
- efferent tract is the facial n.
- Test for potential vision
- not a test of vision
- Use this test if we can’t see the pupil
17
Q
Menace Response
A
- First test of actual vision
- requires intact visual cortex
- learned response
- rapid hand movements or cotton balls thrown at patient behind a clear plastic shield
- patient cooperation is vital
- tough in puppies and cats
- Positive test more meaningful than negative test
18
Q
Palpebral reflex
A
- medial and lateral canthus
- CN 5, 7 test
- no response indicates facial paralysis
19
Q
Obstacle course
A
- conduct in exam room
- change room’s illumination
- use soft obstacles
- quiet essential to avoid leading animal with sounds
20
Q
Summary list of vision tests
A
- menace
- drop cotton ball
- obstacle course
21
Q
Regional anesthetics
A
- Lidocaine
- Carbocaine
- Bupivicaine
22
Q
Regional anesthesia
Blocks
A
- Motor blocks
- facilitate exam
- facilitate procedures
- akinesia: CN 7
- Sensory blocks
- facilitate procedures
- sensory analgesia: CN 5
23
Q
A
- Frontal n. block
- Auriculopalpebral n. block
- CN 7 (Facial)
- prevents lid closure
- also used on an eye that is very fragile
- Lacrimal n. block
24
Q
Auriculopalpebral block locations
A
- curve of zygomatic arch
- top of zygomatic arch
- base of ear (triangular shaped divet)
*can also be done in dogs, not really necesary tho
25
Q
Sensory Blocks
A
- Supraorbital
- aka frontal
- medial 2/3 of upper lid
- Lacrimal
- Line
26
Q
A
60
Q
A
