Originally Posted by
TradeoffH8er
As long as the patients you mentioned aren't using an abnormally close working distance for computer use, it sounds to me like you have a fitting issue on your hands. Office lenses are not meant to be fit at the top of the lens where the add is only say +0.50 D with the add being +2.25 D. The fitting cross should be well below the area near the top of the lens where the full dynamic digression is reached. The add power at the fitting cross should be about 60% of the full Rx add assuming a working distance of about 60 cm (according to a Sheedy article on objective PAL ratings). It sounds like your optics lab is fitting the patient near the top of the lens where the "far" reference pt is. I would check with the lab to make sure that they use the proper fitting point in the future. You should also ask your Shamir sales rep what add power you should expect to measure at the fitting cross for each dynamic power they offer. Clearly, this value should be between the "far" value measured at the top of the lens, and the near value. You should not be measuring +0.50 D add at the fitting cross if the lab is using the correct fitting point for a +2.25 D add lens. Like you said, you should expect to measure somewhere around +1.25 D add at the fitting point.
If for some reason it turns out that the optics lab is fitting the lens correctly, the add power is approximately 60% of the full add at the fitting cross specified by Shamir, and you still have problems, then I would say that working distance is the culprit. One possible example is that patients using a laptop tend to have a shorter working distance than those who use a desktop PC, and the patients you are having problems with could be predominantly laptop users.
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