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What is tonometry?
the measurement of intraocular pressure (IOP)
What is the purpose of tonometry?
use to diagnose glaucoma (increased IOP)
Where is aqueous humor produced?
by the ciliary body and flows through the pupil
Aqueous humor drains from the eye through the _____.
What is the iridocorneal angle?
a sieve-like network located at the junction of the cornea and the iris
Normally, aqueous humor is produced and drained from the eye at approximately the same rate. What is this called?
stable internal eye pressure
What is glaucoma?
increased intraocular pressure
What causes glaucoma?
inadequate outflow of aqueous humor - pressure builds up inside the eye
What can glaucoma result in?
- optic nerve damage
What is primary glaucoma?
no other inciting cause - may be inherited
What are the two types of primary glaucoma?
- open-angle glaucoma
- narrow angle glaucoma
What is secondary glaucoma?
another inciting cause is present
What could be the potential causes of secondary glaucoma?
- dislocated lens
- intraocular tumors
- eye injuries
- diabetes mellitus
How does diabetes mellitus cause secondary glaucoma?
cataracts - leaks protein and causes uveitis or neovascularization blocking drainage angle
What are the three ways to diagnose glaucoma?
- clinical signs
What are the clinical signs of glaucoma?
- excessive tearing
- ocular discharge
- reddened eye
- blue cornea
- dilated pupil unresponsive to light
- pet may sleep or hide alot or become irritable
- later stages - enlarged eye
What is gonioscopy?
technique used to evaluate the drainage angle between the iris and cornea
How do we do gonioscopy?
- placing a goniolens (dome-shaped contact lens) on the eye
- allows direct visualization of the drainage angle
What are the two types of tonometry?
- Schiotz tonometry
- applanation tonometry
Should we squeeze the animal around the neck in restraint when doing tonometry? Why or why not?
no, this will increase ocular pressure
How do we do Schiotz tonometry?
- animal must be positioned either sitting with nose pointing directly upward or on its back
- tonometer must be held vertically
What is used to do applanation tonometry?
Tono-Pen Vet Tonometer
How do we do applanation tonometry?
press the tip of the tonometer against the flattening of the cornea until it beeps
What are the advantages to applanation tonometry?
- portable, easy to use with minimal training
- functions in any orientation
What are the therapies for glaucoma?
- if blindness is irreversible, then we should just relieve the pain and try to maintain the cosmetic appearance of the eye