Lecture 8 - Tonometry 1 Flashcards
When do you perform Tono?
After the SLEx
Note: If you do Gonio first, it will give you different result
What type of focus and movement must be made by using the joystick for tono?
Fine focus and movement
What is Tonometry?
The clinical technique that measures the IOP
Where is the Aqueous humor produced by?
Epithelium of the Ciliary Body
What is the flow of the Aqueous Humor?
Pupil into the Anterior Chamber
What are the 2 routes for Aqueous Humor?
- “Conventional Route”: passes thru the trabecular meshwork into Schlemm’s canal. Exiting via collector channels into venous system
- “Unconventional Route”: passes thru the uvealscleral pathway. Passes thru the iris root uveal meshwork and the anterior face of cilary muscle à thru suprachoroidal space and on out thru sclera (Prostoglandins can be used)
What is the outflow percentage of Aqueous Humor Outflow?
Trabecular outflow 70% or more
Uveoscleral outflow 30% or less
What is the 3 IOP purposes?
- Maintains integrity of globe
- Maintains retina and choroid in place
- Nourishes the lens, endo of cornea, vitreous and TM
What is the normal range for IOP?
10 to 21
Note: Avg tends to be around 15 mmHg
What is another scientific name when the outflow rate is normal?
Dynamic Equilbrium
What are 2 abnormal changes of IOP?
- Rare is overproduction in presence of normal outflow cause of increased IOP
- Interference with aqueous outflow is the most significant factor in the etiology of increased IOP (MOST COMMON)
What is the main focus of glaucoma therapy in regards to outflow?
Increase outflow and inhibition of production
What drugs focus on outflow of aqueous humor and aqueous production?
Prostaglandin = outflow
Carbonic Anhydrase Inhibitor = production
When you have completed multiple readings, what happens to the aqueous outflow and to IOP?
Increased aqueous outflow
Decrease IOP
What is the diameter of the circular zone of applanation?
3.06 mm
Note: Area is 7.3542
In regards to the GAT, what does 2 grams equal to in mmHg?
20 mmHg
What is the first thing you must do prior to GAT procedures?
Pt. education
Why is it important to remind your pt. that they must not rub their eyes ?
This is so why there is more of an effect on the eyes
What parts do you puntcal occlude?
Nasolacrimal sac and medial palpebral ligament
What are the three chemical components of fluress?
Fluorescein, Benoxinate and Chlorobutanol
What is the wetting agent and stabilizer?
15% Povidone
What do you ask your pts. prior to distilling dyes or anesthetics?
Are you allergic to any dyes or anesthetics
When inserting a tono probe, what markers must be aligned with one another?
Holder = white line
Tono probe = zero axis
When do you align on the red line of the holder?
3D or more of CORNEAL ASTIGMATISM
What is the separation degree between the red and white line on the holder?
43 degrees
Why do we not start the drum set too high?
Since the avg is close to 15 mmHg.
How many degrees and in what direction is the viewing system arm away from the GAT reference point?
5 to 10 degrees away and temporally
Note: GAT must be perpendicular patient’s corneal plane
What is the magnification you use when scanning the cornea after probing?
10x
While looking externally and pushing the slit lamp close to the pts. eye, when is it your indication to start looking through the eye piece of the slit lamp?
Limbal glow
If the mires are too thick, how will that impact the IOP?
Artifically higher IOP
Note: The opposite is true for thin mires
What type of motion occurs when there is venous pulsation?
Lateral motion of the mires
True or False. Mires that come and go means they are pulsating mires?
False. This means that there is not proper applanation
What is the most common type of virus that can occur when you do NOT clean the tono probe?
Adenovirus Keratoconjunctivitis
What type of wash removes all types of viruses available, even HepB virus of the DNA?
Water Wash
What does the AOA recommend when cleaning the tono probe?
70% isopropyl alcohol swab
