Log 3 - Frame Measurements

Question 1

What is MRP and definition

Answer 1

Major Reference Point - ensures that the lens is fit properly decentered. Boxing center of the lens.

Question 2

What is the formula for Frame difference

Answer 2

Frame difference = A - B

- the greater the frame difference the more rectangular the surrounding box looks

Question 3

What is the formula for calculating the GCD (Geometric Center Distance)

Answer 3

GCD= eyesize + DBL

Question 4

What is the formula for binocular decentration of a lens

Answer 4

Decentration = DBC - PD
_______
2
DBC will be nasally or inward if DBC is greater than the PD, if it was smaller the optical center would move out or temporally

Question 5

What is the formula for monocular decentration of a lens

Answer 5

(OD)(OS) Decentration = DBC
——- - PD
2

Question 6

Metal Frames with Gold are classified how (karat system)

Answer 6

1. Fine Gold - 100% pure gold, often too soft for durability - marked 24
2. Solid Gold - 50% gold, 50% metal, θ indicates 10 K Gold and □ indicates 12 K
3. Gold Filled - a base metal inside a gold alloy - likely marked 1/10 12 K gold
4. Gold Plated - a base material thinly plated with gold
5. Gold Flashing - like gold plating but done more quickly using cyanide bath

Question 7

How should you determine proper frame width?

Answer 7

Width should be approx. equal to the widest bony part of the face.

Question 8

Patients with oblong faces need frames with greater ____________.

Answer 8

Vertical Depth

Question 9

The lower the temple “line”, the __________ the face appears.

Answer 9

Shorter

Question 10

Frames with a dark upper rim and nylon cord bottom help ____________ wide faces.

Answer 10

Lengthen

Question 11

Recommendations for patients with base-down triangular faces?

Answer 11

Glasses should be approx. same width as lower facial area

Frame color should be dark

Question 12

Recommendations for patients with base-up triangular faces?

Answer 12

Frame should be minimal, unobtrusive, and light-colored.

Question 13

To “lengthen” the nose of a frame selection

Answer 13

Choose frame that exposes as much of the nose as possible, or consider a keyhole bridge + dark frame.

Question 14

To “shorten” the nose of a frame selection

Answer 14

Consider a saddle bridge. Solid color frame with the top of the bridge coming down as far as possible

Question 15

The angle made by the two sides of the nose when looking at the face straight on is called:

Answer 15

Frontal Angle

Question 16

The angle made by the widening of the nose from front-to-back when looking at the face from above is called:

Answer 16

Splay Angle

Question 17

The angle made from the frontal plane of the face to the front of the nose crest when looking at the face from the side is called:

Answer 17

Crest Angle

Question 18

4 Recommendations for frame size for high-minus wearers?

Answer 18

1. Avoid frames with large lenses
2. Rounded corners on frames are good
3. Avoid frames that are wider than the pt’s face at the temple area
4. Avoid excessive decentration
5. Aspheric or atoric lenses whenever possible
6. Always use anti glare coating

Question 19

3 recommendations for frame size for high-plus wearers?

Answer 19

1. Avoid large lenses
2. Avoid frames with effective diameter more than 2mm greater than eyesize
3. Avoid frame difference >9mm
4. High index lenses
5. Aspheric or atoric lenses whenever possible
6. Always use anti glare coating

Question 20

What are the 3 requirements for selecting a frame for a progressive add?

Answer 20

1. Minimal vertex distance
2. Adequate pantoscopic tilt
3. Vertical depth in nasal portion of frame shape