Keratometry 3% Flashcards
*What is the generic name for Keratometer?
Ophthalmoteter
Keratometer uses what type of mirror?
Front surface
What surface does the Keratometer measure?
The anterior surface of the K
*Keratometer measures in what?
D or mm’s
*What part of the cornea does the keratometer measure?
Central 3mm (corneal cap)
In keratometry.
*In keratometry the prism splits light into 2 images. What are they split into?
Horizontal and Vertical Meridians
*Keratometry is the starting point for _____ fitting
CL
The Difference between vertical and horizontal meridians =
Diopters of corneal astig
For Keratometry the room light must be ____
dim
You must _____the eye piece before performing Keratometry
focus
You must align____ with pts out most canthus
Canthus marker
How do you focus eye piece of Keratometer?
Turn until you have 3 complete circles with the plus and minus lined up together
Explain how to perform manual keratometry
Dim the lights and focus your eye piece. Align canthus marker with pts outer canthus. Have pt blink and open wide. Keep circles in sharp focus. Turn the knobs until the plus signs intersect and the minus signs intersect. Then rotate the keratometer until all of those intersecting lines are perfectly overlapped. This gives you the axis. Then read drums. Horizontal reading recorded first(some prefer flatter then steeper meridian then axis)
When converting readings from Keratometer from mm’s to D
Each 0.05mm=_______
0.5mm radius=________
1D change in K=________
Approx 0.25D
Approx 2.5 D
Approx 0.2 mm radius change
Method of Keratometry that is more accurate than traditional keratometer, is objective, expensive, and good K surface is a must.
IOL Master (aka AUTOMATED Laser Keratometry)
Laser automated keratomter is keratometry with the ______
IOL master
How many peripheral measuring marks are there in IOL Master?
6
When performing IOL master be sure all ________are visible and lying as concentric as possible to the _______
6 marks
2 auxillary circles
What’s most important when doing IOL Master?
Optimally focus 6 marks
Good ________is a must when performing Keratometry with IOL master.
tear film (have pt blink)
What are reasons for “Error” message when doing Laser automated Keratometer(IOL master)?
out of focus, maladjustment, artifacts, surface irregularities.
_________astigmatism means cornea is steeper in the vertical meridian. Plus cynlinder axis is between 60-12-0 degrees.
With-the-rule astigmatism
_________astigmatism means K is steeper in the horizontal meridain. Plus cylinder axis is between 0-30 degrees or 150-180 degrees.
Against-the-rule astigmatism
Axis is between 30-60 or 120-150 degrees.
Oblique astigmatism
