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What is the fitted vertex distance?
What instrument is used to measure the vertex distance?
Which of the following is a variable of the minimum blank size formula
Which of the following is a determining factor in lens thickness?
When do you need to use a vertex distance?
As a plus power lens is moved further away from the eye the perceived power ______.
What is true about lens thickness?
If an order has been determined to have 5mm of decentration in the right eye and the ED of the frame is 54, what is the smallest lens blank this could be ran on?
As a minus power lens is moved further from the eye the perceived power _______.
What is one way you could increase the magnification of a lens?
The variable (a) in Martin’s Tilt formula stands for _______.
What must you add to your answer after using the lens thickness formula to calculate lens thickness?
What formula is used to determine if your lab can process an order on finished lens blanks?
What is usually the best and easiest way to correct an abnormal amount of tilt?
You have determined that an order can be processed on a blank size of 68mm, what would this mean the radius of the lens would be?
When should you use two different lens materials in order to balance magnification between right and left lenses?
What are sine, cosine and tangent ratios of?
Why might a deeper B measurement result in better cosmetic appearance for an individual who has a +5.00 D prescription?
Why might you add 2 mm to your calculated minimum blank size?
If the decentration is increased by 2 mm this will increase the blank size by_____.
You are fitting a patient for a pair of glasses, their prescription is -10.00 OU. What would be the amount of power change per millimeter by changing the vertex distance?
If you determine that the fitted eyewear from the patient above fits 5 mm closer to the patients eye than during refraction what is the power of lens that they would perceive if nothing else is changed?
What power lens should be ordered for the patient above to ensure they perceive the correct prescription?
When adjusting tilt in the 90 degree meridian we are adjusting ______.
What are the controllable factors in the lens thickness formula?
Calculate the expected lens thickness given the following parameters: Rx – 9.00 Minimum blank size 63 mm Material CR-39 (1.50)
The lab was unable to process the order above on a 63mm lens blank due to manufacture availability and a 65mm blank must be used. What is the new expected lens thickness?
You are inspecting a pair of eyewear and need to determine how much prism is in effect at the 180 degree meridian. The prescription is – 3.00 – 1.00 x113, how would you determine how much power is in effect at this meridian?
From the prescription above, how much power is in effect at the 180 degree meridian?
How much power is in effect at 90 degrees for the following prescription: + 3.50 – 3.00 x 40
What is one way to reduce minimum blank size?
When a lens has excessive tilt the patient will experience a change in _________.
When either the vertex distance or amount of tilt is changed the power of the lens ________.
What is an iesokonic lens?
Aniesokonia is a condition where______.
In digitally manufactured lenses some of the measurements used for compensation are _______________.
Why might a higher index lens material not necessarily yield thinner lenses?
The base curve of a lens is increased from +4.00 to +8.00. What effect will this have on the magnification?
How would increasing the pantoscopic tilt of a lens change the magnification?
Who might benefit from the optician taking the time to calculate out expected lens thickness?