By Michael Goodwin LDO, inventor, and CEO of The Pupil Marker
There is a new twist on the old subject of measuring seg heights and progressive lens verification. The "twist" is The Pupil Marker, sometimes known as the "white pen."
Here's how the pupil marker is used for these two processes we do everyday.
First for measuring the proper height of a progressive lens;
After the frame is adjusted to sit level on the patient, and you're sitting eye level, use the pupil marker to dot the frame's lens at the patient's center pupil. The marker will leave a contrasting white dot on the lens making its location much more visible to the dispenser.
Just measuring progressive lens height in a sitting position can be a costly error. Double check each eyes dot placement while seated, then ask the patient to stand up away from the dispensing table. Ask them to look out a window or across the room. Stand 3 to 4 feet in front and slightly to the side of the patient. Odds are that the conversation will have them "standing in a more normal posture".
If the white dots look to be centered properly than all is well. If not, adjust the dots location.
After sitting back down at the table, take one more look and make your final decision on each eye's height measurement. The white ink can be easily removed from any lens material with lens cleaner or alcohol.
For progressive lens verification
Use the pupil marker to re-dot the finished lens. Dot the Prism Reference Point (PRP) and the Fitting Cross.
Often the lab will provide a decal for that brand of progressive lens. Line up the decal on the front of the lens properly and use the pupil marker to dot the fitting cross and the optical center on the backside of the lens. Then remove the decal. For digitally enhanced lenses, the decal will often be on the back, then dot the front.
Use the white dot on the PRP (optical center if there is no prescribed prism or prism thinning) to align your center-marking pin while the glasses are on the lensometer's table. This will allow the dispenser to have a more exact position to check for wanted or un-wanted prism.
Lastly, the fitting cross white dot will allow the dispenser to double check the height measurement while the glasses are on the patient during delivery. Another simple use would be dotting the engraved markings and heights on tinted or polarized progressive's lenses.
The white ink is acid free and harmless to all lens materials and coatings and it's made in the USA. Pupil markers are distributed by Ron's Case Company in the U.S. and The Norville Optical Group in the United Kingdom. See www.thepupilmarker.com for more info.