Computer RX

[Leighlee]

Question, if the RX is:

OD: -1.75 Sph
OS: +0.25 + 0.25 X 80
+2.50 Add OU

The Patient wants FT-28 with Computer RX in top and Reading in bottom.
What would RX for these glasses be?

[Uncle Fester]

Question, if the RX is:

OD: -1.75 Sph
OS: +0.25 + 0.25 X 80
+2.50 Add OU

The Patient wants FT-28 with Computer RX in top and Reading in bottom.
What would RX for these glasses be?

I usually make the add +.75 So the rx becomes

R 0.00
L+2.00 +.25 x80
Add +.75

Leighlee- Do you see the reasoning in getting to this answer?

Also has the patient worn FT before?

[Fezz]

How far frm the screen?

How far from the keyboard?

Will the prescribing Dr. ok any changes made to original rx?

[Leighlee]

I usually make the add +.75 So the rx becomes

R -1.00
L+2.00 +.25 x80
Add +.75

Leighlee- Do you see the reasoning in getting to this answer?

Also has the patient worn FT before?

I understand the OD power, I don't understand the OS power.

[Leighlee]

How far frm the screen?

How far from the keyboard?

Will the prescribing Dr. ok any changes made to original rx?

He has worn progressive, but finds them too small of a reading when working at the computer. 22-24 inches away from screen. He wants to be able to lay papers out on desk in front of computer screen, and be able to glance up at screen and still have larger reading area to see papers. And I will check with Dr to ok RX first.

[Leighlee]

I usually make the add +.75 So the rx becomes

R 0.00
L+2.00 +.25 x80
Add +.75

Leighlee- Do you see the reasoning in getting to this answer?

Also has the patient worn FT before?

Ok Now I don't understand either power for either eye. It was sort of making sense until you changed it, now I am baffled. It seems you are working back up from the Add to the distance RX?

[Leighlee]

:idea: OK....I get it. But how do you come up with the +75 add?

[HarryChiling]

You really need to know the working distance and also the working distance for the prescribed Rx all this should be included.

[Uncle Fester]

Fezz and Harry are right that you need more specific info to really nail the rx but as a rule most people are about 10 or so inches further from the screen than the keyboard. Also you can't get +.50 adds (except round segs from 3 Rivers optical) in Flat tops CR or poly as much as I wish they would!

Each quarter diopter you decrease the add moves the focus back or "out" a couple of inches. (I'm being lazy here and not converting to metrics as I should). So if we weaken the near by 0.75(or minus 0.75) we'll move the focus back that little bit that most people sit at from their screens.

So let's convert to just a near rx. You would get
R +0.75
L +2.75 +0.25 x80. So if we are creating a bifocal with an add of +0.75 we'd subtract that from the sphere to change the upper lens powers to
R 0.00
L +2.00 +0.25 x80
Add +0.75

Clear as mud? :D:p:D

Regards:)

[Against the Rule]

I usually make the add +.75

I'm not understanding why that is.

[braheem24]

Question, if the RX is:

OD: -1.75 Sph
OS: +0.25 + 0.25 X 80
+2.50 Add OU

The Patient wants FT-28 with Computer RX in top and Reading in bottom.
What would RX for these glasses be?

The most popular technique is to add half of the bifocal power to the distance power and the other half to the bottom.

Final RX would be:

-0.50 sph
+1.50+.25x80
1.25 ADD


I see you got more questions then answers, Hope that gives you a general answer if that's what you were searching for.

[Leighlee]

The most popular technique is to add half of the bifocal power to the distance power and the other half to the bottom.

Final RX would be:

-0.50 sph
+1.50+.25x80
1.25 ADD


I see you got more questions then answers, Hope that gives you a general answer if that's what you were searching for.

Well I can understand what Fezz is saying, and I understand what you and the rest are saying too. With so many people dependent on computers to do their jobs these days...I was wanting to hopefully nail down a technique or formula to go by, or at least a starting point...where I could calculate distance from the screen into the mix...but I guess there are too many variables to be able to do this? BTW, distance from the keyboard and distance from the screen are pretty close to the same, this is a very tall man...6'6". Maybe I should just do a single vision lens, but that might sacrifice his reading of paperwork which would be closer.

[Fezz]

Braheem is giving some good advice. Uncle Fester has given some pears of wisdom as well! What we are really trying to show you is - every situation, patient, is different!

Some patients will be best served by a Ft, some by one of the computer progressives, some by single vision. It all depends on many things.

Do you have access to a trial frame and lenses? Do you have access to "flippers" that have lets say a set of -1.00's and +1.00's. These come in very handy when trying to demonstrate to a patient what you are trying to achieve in a computer lens. It is very quick! I like the adding half off the bifocal power! That technique gets you very close (usually!).

Do you get Eye Care Professional Magazine? Rumor has it that there is an article written by a really smart, snazzy dressing, beer guzzling, forward thinking, helpful, Schmuck that deals with this very topic in the upcominging issue!

;):cheers::D:cheers:;)

You might want to check that rag out. It is really a great trade journal. Many of our Optiboard Stars contribute to it!


www.ECPmag.com

1-800-914-4322

[Leighlee]

Why Fezz...would that really smart, snazzy dressing, beer guzzling, forward thinking, helpful guy be YOU by chance?

[npdr]

Computer prescriptions may be generalized but in general one must divide up the world between use at work vs use at home and use with a laptop vs desktop.

If everyone used a laptop, then this adjustment of lens power in the major lens need to be made because most of the "reading" angle is between 20 to 35 degrees down gaze.

Most of the problems of using PALs for computers can be negated by a more interactive approach with the customer. In many cases, a higher point for the start of the transition zone is all that is needed.

[chip anderson]

Unless the computer is at a distance far greater or closer distance than usual, it's simple: Add 1/2 of add power to sphere distance power and use this for the top, now put 1/2 of the near power for the add.

What's simpler than that?

Both people and computers move, this need not be calculated to the 10 mm of focal length.


Chip

[Fezz]

Why Fezz...would that really smart, snazzy dressing, beer guzzling, forward thinking, helpful guy be YOU by chance?

Oh No..............

I am far too humble to ever boast, brag, exaggerate, lie, cajole, and pat my own back like that!

:cheers:;):cheers::D

[drk]

Does it help to conceptualize "borrowing" add power from the bottom of the lens and "moving" it to the top of the lens?

[chip anderson]

Simple: The middle of a trifocal is 1/2 the add power (and focuses at arm's length to 6 feet) which works well for computers and wall mounted telephones as well customers across the dispensing table. If this is used as the distance (top power in computer glasses) it focuses on the computer screen from arm's lenght to 10 feet, it also leaves the cylinder power at both distances unchanged. If 1/2 of add power is again used at the near (total full reading addition when combined with the intermediate power which is being used at the top of the lens) which has not been changed it still focuses at 14-18" for reading printed matter.

What's so hard to understand?

Chip

You are essentially useing intermediate power for upper and near for lower.
Those of you old enough to understand lined trifocals should have no trouble with this.

[Dougfir8]

Fezz and Harry are right that you need more specific info to really nail the rx but as a rule most people are about 10 or so inches further from the screen than the keyboard. Also you can't get +.50 adds (except round segs from 3 Rivers optical) in Flat tops CR or poly as much as I wish they would!

Each quarter diopter you decrease the add moves the focus back or "out" a couple of inches. (I'm being lazy here and not converting to metrics as I should). So if we weaken the near by 0.75(or minus 0.75) we'll move the focus back that little bit that most people sit at from their screens.

So let's convert to just a near rx. You would get
R +0.75
L +2.75 +0.25 x80. So if we are creating a bifocal with an add of +0.75 we'd subtract that from the sphere to change the upper lens powers to
R 0.00
L +2.00 +0.25 x80
Add +0.75

Clear as mud? :D:p:D

Regards:)

You can get .50 add FT28's in plastic from Vision Ease and X-cel. Both companies list this on their current catalogs and wall charts. Bad news is that they are uncoated.

[DragonLensmanWV]

Oh No..............

I am far too humble to ever boast, brag, exaggerate, lie, cajole, and pat my own back like that!

:cheers:;):cheers::D

cough, cough, cough.Ok, breathe, easy...easy..whew! Reality is now back to norbal.

[Uncle Fester]

You can get .50 add FT28's in plastic from Vision Ease and X-cel. Both companies list this on their current catalogs and wall charts. Bad news is that they are uncoated.

Excellent! I didn't know they heard me!!:bbg:

[Eyedoc71]

You could always just ask their doctor what they want them to have.

[Uncle Fester]

Unless the computer is at a distance far greater or closer distance than usual, it's simple: Add 1/2 of add power to sphere distance power and use this for the top, now put 1/2 of the near power for the add.

What's simpler than that?

Both people and computers move, this need not be calculated to the .10 mm of focal length.


Chip

Leighlee- Chips got a great rule of thumb with this formula. Our office tends to increase the magnification in the upper area however. But that's us! For most computer user's a half add formula will work fine.

[Fezz]

You could always just ask their doctor what they want them to have.

Good point Doc.

How would you handle this if you gave a patient their rx, they split, and the optical professional that they decided to purchase from called you to ask you what is the computer rx?

I am curious, because I have had a wide range of answers from Docs(both Md's and Od's)- when I have called to ask the very same questions.

Most of the answers were something along the lines of:

1.) "I didn't check them for that."
2.) "Just use a computer progressive."
3.) "What do you think?"

Responses:

1.) "Should I send them back to you?"
2.) "Since you are suggesting that...could you write out what progressive you prescribe?"
3.) "You refracted them---what do you think?"


So, as a rx writing Optometrist,....how would you suggest this situation is handled?