Degressive varifocals to Conventional

[snoozy]

I have a customer who I have switched from Degressive lenses which he was not too keen on to Conventional PAL.
However although distance is better as you would expect he feels having to look through bottom of lens now instead of higher gaze position with degressives he is struggling to read small print.

If I increase add by 0.25 do you think this will help?

Old Rx R +1.75 +0.25 30 L +1.75 Add 200

New Rx R +2.00 L +1.75 +0.50 170 Add 200

Do you think should increase or decrease heights a little also?.

[chip anderson]

That's why Ben Franklin invented Bifocals. And some other good soul came along and added trifocals.

[DragonLensmanWV]

bumping the add will likely not help. He is going from an intermediate/near lens design to a far/near design. I'm guessing he thought he could see to drive with his Near Variable Focus lenses?

[chip anderson]

Who did actually invent the trifocal?

[Robert Martellaro]

If I increase add by 0.25 do you think this will help?

No, but if you add it to the distance it will. However, two pair is the proper solution, assuming that the symtoms and frequency of use at intermediate (I assume these are for a desktop monitor) justifies the added expense and inconvenience.

[chip anderson]

Not really too sure what a degressive is. But do you know about PC Peekers? They might be applicable but I must admit I don't really understand your decription of the problem.

Chip

[Jonathan Becker]

Who did actually invent the trifocal?

John Isaac Hawkins is credited with inventing the Trifocal

http://en.wikipedia.org/wiki/John_Is...s#cite_note-17

[iiiiisoptom]

I'm not really familiar with the term "degressive lens), but I assume you mean an extended range or intermediate/near progressive lens.

Before answering the question with any great conviction, I would want to know what the design of both the "degressive lens" and "conventional PAL" were. Also, what was the patient's chief complaint about the current lenses?

I think the design and corridor length of the PAL may be the critical factors.

I would consider increasing the distance plus by +0.25OU, drop the fitting height by perhaps 0.5mm, and change to a shorter corridor design.

If the patient has been correctly refracted for distance, he should accept the +0.25 overcorrection at distance, with the slightly lower fitting height reducing the likelihood of distance fogging. However, despite the reduced fitting height, the full addition should be reached earlier due to the shorter corridor length.

To solve this problem, I believe you have to listen closely to what the patient has to say.

[KStraker]

"The majority of computer lenses can best be described as having a range or degression, a loss of power from reading to intermediate. These lenses are progressive in design but instead of adding power, they are designed to reduce power."

The degression is the difference in the power between the top and the bottom. With the office lens, you don't have to tilt your head back to use the intermediate. Handy for a PC, but not so much out in the world. What is the goal of the patient? Is this a lens for every day use, or a task specific lens that would require an office design? If it's an every day lens, whey was he using an office design?

I don't see how dropping the seg ht will get him in to the add any faster. With a 2.00 add I would consider a short corridor if he doesn't have much use for the mid range.

[HIEYEGUY]

You do not say why he was not keen on the degressives. If made in a high end design such as the Shamir Office, they can be quite successful in a an office setting. The design is not the same as if you just gave intermediate power on top and then added enough power to achieve the near add in a regular progressive. However they do not give satisfactory distance vision (they were not meant for that)
Since he is complaining of near vision, consider giving the proper distance with a +2.50 add in a high end free form progressive. These will give him that good near vision and a higher position for the good intermediate vision that he is looking for.