Understand a prescription Flashcards
What is the sphere power written in as?
It is written in diopters and will indicate the amount of correction needed.
What is another word for no power in Rx?
- Plano (pl)
What is another name for a prescription that only has a sphere power?
A diopter sphere (D.S.) or Sphere (sph) will be added to show that the cylinder and axis haven’t been forgotten.
Most doctors write their prescriptions in quarter steps but diopters can be broken down to an eighth of a diopter step. What are they?
0.00
0.12
0.25
0.37
0.50
0.62
0.75
0.87
What does it mean when the value is listed under the cylinder portion of the prescriptions?
The patient has astigmatism.
What is the difference between Optometrists & Ophthalmologiests
- Optometrists are regular eye doctors
- Ophthalmologists is an eye doctor that can do surgery’s
What does the axis mean in a prescription?
- The axis is a number from 0 to 180 degrees that provides information for where the lens power is located.
What does ADD mean in the prescription?
- Patients who need help with near vision will have a reading add
- The number will be the same for both eyes and will always be a plus number ranging from +0.75D to +3.00D
What does “PAL” mean?
- “PAL”= Progressive lens
- PAL is the notation for progressive lenses.
What is “FT28”?
- “FT28”= Flat top 28
- Refers to a flat top 28 mm wide bifocal
What is TRI?
- “TRI” = Triocal
- Refers to a traditional trifocal design.
What is the Trifocal power percentage?
- Traditional Trifocal power is usually 50% of the add
- Intermediate Trifocal power can be noted as a percentage of the added power.
How is prism noted?
- Prism is noted in diopters along with direction.
What does “PD”?
- “PD”= Pupillary distance
- Noted in millimeters
- ADD powers requires near PD
What is the formula of the lens power?
F1 + F2 +F total
(front curve plus back curve equals total power)
Use the lens power to solve the problem
Front curve = +6.00D
Back Curve = -4.00D
+6.00D(+) -4.00D = +2.00D
What is cylinder power?
It is the difference between the powers of the two meridians
What is Transposition?
Changing the cylinder designations from one form to the other
What do you do when the signs of the sphere and cylinder power are the same?
Add them together and keep the same sign
What do you do when the signs of sphere and cylinder power are different?
Subtract the smaller number to arrive at the new sphere.
Transcribe the Rx
+2.00 -1.00 X 85
+2.00+(-)1.00=+1.00D
new sphere
-1.00 becomes +1.00D
New cylinder
85+90=175
new axis
Plus cylinder form: +1.00 +1.00 x 175
Transcribe the Rx
Plano +2.00 x 100
Plano + (+)2.00 = +2.00D
new sphere
+2.00 becomes -2.00D
new Cylinder
100 - 90 = 10
new axis
+2.00 -2.00 x 10
Show/explain how the sizing of the lens to the frame.
RX -3.00 -2.00 x 90
-3.00D on vertical meridian
(sphere and axis go together)
-5.00D on the horizontal meridian
(add sphere and cylinder powers)
(This is going to make the lens edge thickest in the horizontal meridian)
Use reading Additon
Distance Rx +2.00 -1.00 x 45
Add Rx +2.00
Reading Rx +4.00 -1.00 x 45
