When there is a distinct difference between the lower limbus and lower lid, use the lower limbus as a reference for bifocal heights.

A patient wants to order bifocals. Their segment heights are OD: 17 and OS: 14. You should order the same segment height for both lenses.

When the pantoscopic tilt is decreased, the apparent height of the multifocal segment is decreased.

Why do children require segmented multifocals?

A patient requires a 50-16 sized frame but you only have the frame in a 54-16 size. If the progressive multifocal height in the larger frame is 19 mm, what would the height be in the smaller frame?

Progressive multifocal lenses have a fairly narrow ___________ corridor between the distance and reading portions of the lens. 

For a double segment lens, a 7 mm upper segment height is acceptable.

The patient has dissimilar sized pupils. The distance from the outer edge of the patient’s right pupil to the inner edge of the left equals 54 mm. The distance from the inner edge of the right pupil to the outer edge of the left equals 58 mm. What is the patient’s distance PD?

What is the proper placement of a bifocal segment for a child?

When taking a binocular near PD with a ruler, at what distance must the optician be from the patient in order to get an accurate reading?