The Boxing System Basic Measurements For Eyewear Flashcards
Which system measures the PD using a corneal reflex?
Pupilometer and PD meter
What is the geometrical center distance of a frame marked 52/17?
69
In the boxing system, the effective diameter is the diagonal of the box.
False
The larger the frame difference, the —– the lens shape
Narrower
What is the DBL of a frame and how is it measured? Be specific.
Distance between lenses or bridge size is measured on the frame as the distance from the inside nasal eye wire grooves across the bridge area at the narrowest point.
If lenses are decentered in a frame by 4mm, this will also change the location of the geometrical center distance.
False
Before ordering prescription eyeglasses or even performing a visual examination what measurement must be determined?
The patients PD
When taking a PD with a ruler, how far away should the optician be from the patient for a distance PD and then for a near PD?
40cm/16inches for distance
At the patients working distance for near
When using a pupilometer, the cross hairline is adjusted to which point?
The center of the corneal reflex
Using Gerstmans three-quarter rule, what is the near PD for a patient who has a distance PD of 64 with an Rx of OU -1.00sph, +2.50 add, and is using a working distance of 30cm?
1/.3=3.33
.75 x 3.33 = 2.49 or 2.5mm in per eye
NPD = 59
The distance PD measures out to be 62mm, and the near PD calculates out to be 56mm.
What is the seg inset per lens?
3mm
The limbal edge may be used as a reference point in taking monocular PDs.
False
What is the maximum near working distance that should be measured when the add prescribed is +1.50? What would normally be chosen?
66cm
40cm
The major reference point on a lens is also known as the optical center.
True
The major reference point on a lens is also known as the prism reference point.
True
