Week 2 - Objective Flashcards
What are the 6 parts to an objective assessment?
1 - Visual acuity
2 - Keratometry
3 - Corneal Topography
4 - Slit lamp assessment
5 - Lens fitting
6 - Observe CLs fit
Do we take VAs at the start of the evaluation with the ROOM LIGHTS ON without gls and cls in/on?
Yes
What do we record when we take VA measurements?
-Distance and near VA’s
-binocular
-monocular recording
We measure the VAs with and without cls in.T/F
True
What is keratometry? 2
-is the measurement of the corneal apex of the cornea.
-Measures the flattest and steepest curves of the cornea
What does a keratometer measure? 4
- the corneal radius of curvature
-corneal astigmatism
-the quality of the corneal refracting surface
-the base curve selection for contact lens (GP + Soft lenses)
In contact lens fitting,
the keratometer should be used on
every new patient and on rechecks T/F
True
What is the K measurement?
the measurement that parallels the steepest zone of the flattest primary meridian
What is the steepest zone in the cornea?
the apex of the cornea
What unit is used with K readings?
Dioptres
Dioptric values can be converted to mm to figure out base curve T/F
True
If the mires are CLEAR BLURRY CLEAR (clear before the blink/blurred right after the blink/clear again) how do the soft contact lenses fit?
The lens fits flat, try a steeper fit
If the mires are BLURRY CLEAR BLURRY (blurry before the blink/clear right after the blink/blurry again) how do the soft contact lenses fit?
The lens fits steep, try a flatter fit
What charts are used to measure VAs (distance and near) ? 3
Snellen
Digital VA chart
Reading Card
What do we make sure we note when we write the VAs down?
OD/OS/OU - keep track of the eye being measured
When do you move on with the line or stop and record during the VA measurements?
When they get the majority of the letters correct
How do you write the VAs if they dont get the entire row but can read some of the one below or above?
For examples
20/40+1 if they got the entire row of the 20/40 and 1 letter of the 20/30
20/20-2 if they got the majority on that row apart from 2 letters.
What are the 3 types of corneal astigmatism?
-‘with the rule’ astigmatism
-‘against the rule’ astigmatism
-oblique astigmatism
What is the steepest meridian in with the rule astigmatism ?
Vertical Meridian
How will a patients prescription reflect they have an with the rule astigmatism?
- rx will have an axis within 30° of the 180 line
-it will fall within 001 -30 or between 150-180 degrees.
In glasses with the rule astigmatism is corrected with a minus cylinder in the horizontal axis. Why?
This creates a steeper
horizontal meridian
thereby neutralizing or
balancing the steepness of
the vertical meridian of the eye.
What is the steepest meridian in against the rule astigmatism?
Horizontal meridian
How will a patients prescription reflect they have an against the rule astigmatism? 2
-The pxs prescription will reflect this by having an axis
within 30° of 090 line
-The axis will fall somewhere
between 060-120°
In glasses against the rule astigmatism is corrected with a minus cylinder in the vertical axis. Why?
This creates a steeper
vertical meridian
thereby neutralizing or
balancing the steepness of the horizontal meridian of the eye
