Opthalmic Exam Flashcards
What are the 3 main areas of concern that owners normally present their pets with?
Altered appearance of the eye
Loss of vision
Pain
What does protrusion of the globe AND the third eyelid indicate and why?
A space occupying lesion behind the eye. Normally the third eyelid comes across as the eye is withdrawn, displacing the fat pad. In health the third eyelid would not normally come across with a protruded eye hence it is likely that something is pushing the eye and the third eyelid out from behind e.g. neoplasia, abscess, fluid etc
Which species can move the third eyelid voluntarily (to a degree)
Cats
How should you place a STT strip?
Do this before anything that might agitate the eye and cause tear production (e.g. light, eyelid manipulation). Bend the strip in the packet, retract the lateral lower eyelid and place in the lower fornix laterally. It should touch the cornea once hooked but not poke the cornea as you place it.
How long should you wait per eye for STT?
1 minute
Why is it important that the tear strip is placed laterally?
Tears pool in the medial canthus so may give false reading, interference from the third eyelid would alter the result
What is considered normal and low readings for STT1? (remember to consider in context of other signs e.g. ulcer)
Above 15mm/min=normal
Lower than 10mm/min=low
In between is unclear, repeat at another time
What is the menace response?
Part fingers quickly in front of eye. (Do not touch the hairs, vibrissae or eyelids, and do not fan hand in front of face.) It is a learned (cortical) response not a reflex. A very crude test for vision
What is the anterior chamber?
The area in front of the iris
What is the posterior chamber?
The area between the iris and the ciliary body (tiny)
What is the anterior segment?
The area in front of the lens
What is the posterior segment?
The area behind the lens (vitreous humour etc)
What are the three classes of light examination techniques?
1) Transilumination/Slit examination
2) Direct Opthalmoscopy (DDO and CDO)
3) Indirect Opthalmoscopy (IO)
What can be assessed by slit examination/transillumination?
Anterior structures of the eye-eyelids, conjunctiva, third eyelid (non-transiluminable)
cornea, iris, anterior lens (transiluminable)
Reflexes-PLR (direct and indirect e.g. L to R)
What is the blue light on an opthalmoscope used for?
Fluorescein staining
What beam would you use for looking at surface architecture?
Circular, bright beam
Look for overall brightness and moisture, white conjunctiva, sharp and smooth purkinje reflexes
Do blinding cataracts effect PLR and dazzle reflex?
No!
How thick is the cornea?
0.5mm
What is an indirect PLR?
When you shine a light on one eye, the other pupil also contracts (indirect)
How well can you assess ulcer depth with a slit beam?
Not very well-need a slit lamp referral technique as expensive equipment and difficult to interpret
What is flare?
Protein/cells in the anterior chamber (aqueous humour)
What layers will you see highlighted by the slit beam?
Cornea, anterior chamber, iris, anterior belly of the lens, lens, possibly posterior belly of the lens
What are the seven changes in the AC visible with light examination? (TKHHPAA)
Tyndall effect (flare) Keratic precipitates Hyphema Hypopion Posterior synechia Anterior lens luxation Anterior presentation of the vitreous
Where is the aqueous humour made and where does it drain through?
It is produced in the ciliary body and it drains via the iridocorneal angle
Why do keratic precipitates settle at the bottom?
Gravity
What is aqueous flare or the Tyndall effect?
Light reflecting of proteins in the aqueous humour. Indicates inflammation in the anterior chamber
What are keratic precipitates?
Cells deposited on the ventral endothelium of the cornea, occurs as a result of inflammation of the iris or cilliary body
What is hyphema?
Blood in the anterior chamber
What is hypopion?
pus (white cells) in the anterior chamber
What is synechia? posterior and anterior
Posterior synechia is when the iris adheres to the lens, anterior synechia is when the iris adheres to the cornea. May lead to glaucoma
What is anterior lens luxation?
The lens is infront of the pupil, often in the anterior chamber. Leads to closure of iridocorneal angle and hence glaucoma
What is anterior presentation of the vitreous?
vitreous humour in the anterior segment
How should you do a fluorescein test?
Strips better than drops
Adheres to stroma (hydrophilic) repelled by epithelium, wet strip with saline and apply a drop onto dorsal conjunctiva, rinse with saline. look for ulcers. BLUE LIGHT
What is a Jones test and how do you do it?
Do not rinse out fluorescein, wait up to 4 mins and see if flows to nose via NLD, look with blue light. If doesn’t reach the nose may be blocked-indicates flushing
What are the three methods for checking intraocular pressure? (aka tonometry)
Indentation-old, cheap, inaccurate
Applanation-tonopen vet, new expensive, accurate
Rebound-Tonovet, new, expensive, accurate
what is the normal range for IOP?
12-22mmHg
What 2 conditions can IOP help you to distinguish from one another?
Glaucoma vs uveitis although NB long standing uveitis can lead to secondary glaucoma
What is Gonioscopy?
Measures the iridocorneal angle through which aqueous humour exits. Narrow or closed ICA doesn’t always correlate to glaucoma
