Measure For Measure

Q Do you measure round or blended segment bifocals differently than flattop bifocals? If so, what should be taken into account?

A Round and blended segs should be measured differently than flattops. Measure a round seg at the lower lid or 1mm above the lower lid depending on the patient and the head position.

Fit blended segs the same as round segs, keeping in mind that there are 2 to 3mm of blend.

For example, if you order a 28mm seg height in a blended bifocal, you get approximately 25mm of usable seg. You need enough height to give the patient the ability to achieve full add power.

� Steve Seibert, president, Three Rivers Optical, Pittsburgh

Alignment Assignment

Q What are the steps in a basic eyewear bench alignment?

A For all frames, make sure that the nosepad arms flow along edges of lenses and that temples are parallel to each other.

Right side up four-point stance: bottom of each lens, tip of each temple. Upside down three-point stance: across top of lenses and top of each temple at point of bend. Temples should be tight and lenses should be tight in the frame.

There should be no marks on the frame, no lens warpage or distortion, and no gaps between lens and frame. The frame should also be completely clean.

For plastic frames, ensure there are no rolled frame grooves, heat marks, or burns.

For metal frames, there should be no gaps at the closure or temple to end-piece junction, no damaged screws, and no sharp screw edges. Screw style, size, and color must match the frame and each other.

On rimless frames, ensure there�s no dirt in the groove or monofilament. Grooves must be even and string must be secure in the groove.

Monofilament should be the correct color, and screw style, size, and color must match the frame and each other.

On drill mount frames, there should be no cracks around the drill holes, no tool marks on lenses, and no damaged or sharp edge screws. Also, note that the screw style, size, and color must match both the frame and each other.

� Paul Zito, president, Encore Optics LLC, South Windsor, Conn.