I've never really thought there is enough power in the top of this office lens.We just had 2 people recently with adds of 2.25 and 2.50 who both needed the dist. power changed by +0.50 for the top to work without raising the chin. According to Shamir we shouldn't have to do that. Anyone else notice the same and are other office lenses different?
Bob Taylor
Hello,
If the lab used the recommended "Dynamic Power" (regression of plus power, if you will), then your patient should end up with a 'distance portion' over-plus by approx. +0.50 D. It is not really a distance portion...it has an end-point of 10 - 13 feet, depending on Rx.
With this in mind, all Rx's end up approx. +0.25 - +0.75 more plus than their distance Rx. This brings the focus in from 20 feet, to 10 - 13 feet, depending on Add Power.
It is really important that we let the client know that, by gaining an edge-to-edge Intermediate, the 20 ft. distance focus is sacrificed. Given that most small environments/office spaces are within a 10 - 13 ft. distance, the gain outweighs the sacrifice. There should not have to be any computation of the Rx...the dynamic powers automatically yield the vision out to 10 - 13 feet. I know that, as opticians, we want to check the distance portion. We can neutralize it, and remember to expect the additional plus (+0.25 - +0.75 over the distance Rx.)
Hope this helps,
: )
Laurie
I would think that you would have had to change the distance power by -0.50 D and lower your chin in order to get clear distance vision through the top of an office lens. Of course, doing that would also make the reading power come up 0.50 D short. Regardless, the Shamir Office lens is not designed to provide clear distance vision to inifinity for the add powers greater than +1 D. This information is available on Shamir's own website, and I have provided the link below:Originally Posted by rdcoach5
http://www.shamirlens.com/ecp/office_patented.aspx
If the sales reps did indeed promise you clear distance vision (to inifinity) for add powers of +2.25 and +2.5 D, they weren't telling the right story.
I take the OP as they needed +50 more for the intermediate zone, not distance. I don't use that lens so I don't know how its powers are split up, it could be just the patients working distance (intermediate) is closer than norm.
I meant that computer dist needed +0.50 so that the pt. did not have to raise her chin for computer .When I check the normal dist portion of the lens, I only get an add of +0.50. If I were using an exec bif , I would never only use +0.50 add for computer or music. That's my point. There is not enough add in the top of the lens to just enter in the pt's Rx if they need a +2.50 add.Normally I'd use +1.00 or +1.25 in the top depending on work dist.
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.
It just dawned on me that the patients who are having trouble are probably non-typists, like myself. I look at the keys because I never learned to type.So they want to look down at their keypad and be able to read their monitor through the top of their lenses. for these patients, maybe raising the seg would work instead of adding power. Anyone tried this?
I think changing the fitting point, or effectively the SEG height as you suggested is the more logical approach if that is trully the case. I don't like increasing the add power by +0.50 D because then the full add is +0.50 D too high. I would still check and make sure that the add is not +0.50 D at the normal fitting point for a +2.25 D lens. Again as you said, it should be around +1.25 D if the optics lab is processing the lens correctly.
Have you thought of the Zeiss Business lens? These lenses have the full reading power in the bottom third of the lens. You have a choice of +1.00 or +1.50 add. The lens reduces in power towards the upper portion. I usually fit this with patients that work in a cubicle type atmosphere. This lens gives the user more intermediate area higher up in the lens. The Office, I fit people that work in an office atmosphere or who look up alot such as a receptionist at his/her desk.
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