lenses and frames
TRANSCRIPT
MDA – Greater width of the rim or diagonal -Obtained by scanning with the rulerPA – Bridge+Rim - as always in the height where position the optical centers.
A – width rimB – lens heightDEL – Distance between lenses
The virtual rectangle that contains the rim determines the dimensions of the frame.
• Influence in the analysis frame, as measurements are marked on the stem width "bridge" refers shaft length where the proposed new "bridge" is in fact the distance between the lenses.
• This can influence particularly in automatic assembly where assemblers use the bridge information to fitting rimless and semi rimless glasses.
Big Frames
dm – Fitting decentralizationda – Height decentralization
𝑑𝑚 =𝑃𝐴 −𝐷𝑃
2=
𝑃𝐴
2− 𝐷𝑁𝑃
∅ = 𝑀𝐷𝐴 + 2 × 𝑑𝑎 𝑜𝑢 𝑑𝑚
Whichever is greater𝑑𝑎 = 𝑓𝑖𝑡𝑡𝑖𝑛𝑔 ℎ𝑒𝑖𝑔ℎ𝑡 −
𝑟𝑖𝑚 ℎ𝑒𝑖𝑔ℎ𝑡
2
Fast way to determine diameter
- 30,00 dioptrias +20,00 dioptrias
This type work performed in the left minus lenses was called "visodrop" or "myodisc" is an alternative to strong diopters.