+25.00 Add ??!!

**Christosfer** · 08-30-2008, 09:33 PM

In fifteen years I have not had the chance to do an Aphakic lens. So I could use some help. First of all I am concerned that the Doc changed the add from +20 to +25, although her last exam was in 1999.
It looks like she is wearing a curve top of some sort.

Here is the thing that I don't get, she reads at about six inches and I am thinking that another 5.00d is not going to make that better. I don't have much low vision knowledge so I could use some advice here.

Some other questions:
What kind of turnaround time should expect on a lens like this?

Why would someone with an rx like this come in 20 minutes before closing? :hammer:

**sarahito** · 08-30-2008, 09:59 PM

Assuming the doctor gave the exact, full distance correction for the patient, a +20 add would result in a working distance of 5 cm. and a +25 add would result in 4 cm. That's not much difference, but then again, if he had changed it more, the patient probably wouldn't be able to see with both eyes from holding the paper too close, and if he kept it the same, the change would be even less. Maybe the patient just wanted it stronger and the doctor had to give him something to appease him. Personally, I wouldn't even give a +20 add. I'd probably give the patient less of an add and have him use another device, in conjunction with the glasses, like a magnifier. At that close of a working distance, the patient will probably require headlights to see.

**braheem24** · 08-31-2008, 08:33 AM

is it even possible to fuse the images without BO prism at 4cm?

**Dougfir8** · 08-31-2008, 07:33 PM

The only source I know for these lenses is Aire-O-Lite, and they make the blanks for labs. It is probable you can only get round 22 lenticular in this power. If they are in stock, your lab can get them next day, and could process them in a few days. However, I suspect they will go slow to be careful with these $60/pair lens blanks. Also, the company does not allow returns, so we used to order only what we needed, no backup pair, and sometimes had to reorder. [IMG]file:///C:/DOCUME%7E1/Charlie/LOCALS%7E1/Temp/moz-screenshot.jpg[/IMG]800-654-6545 Call them and ask about availability, or ask your lab.
http://www.aire-o-lite-optical.com/

**chip anderson** · 09-01-2008, 12:17 AM

Just bend the nose pad and temple to increase or decrease the vertex as required. You will accomplish as much as increasing/decreasing power in this range. Patient really needs some sort of telescopic (telecopters) with this type of poer.

Chip

**sarahito** · 09-01-2008, 01:31 AM

For any high add given above the normal range, base in prism is needed for convergence. The lenses tend to be very thick, so have had patients actually request less add and sacrifice some vision because they were afraid of discrimination in the workplace.

**Chris Ryser** · 09-01-2008, 06:03 AM

I would blame the operating Ophthalmologist for not having used a proper implant to get a basic correction that brings the eye to just about to 20/20 for distance.

Having paid $ 199.00 times 2, one for each eye lets me see better today than I have in years. It probably also beats the cost of the glasses you have to make now.

**Christosfer** · 09-01-2008, 11:48 PM

Originally Posted by braheem24

is it even possible to fuse the images without BO prism at 4cm?

I was thinking along those lines too. I am wondering how I might get a good near pd, she will probably not see the target in the pupilometer. I think I will do the old ruler on the nose bit.

I don't recall seeing any prism in her previous Rx.

**coffee joe** · 09-02-2008, 02:42 AM

Originally Posted by Chris Ryser

I would blame the operating Ophthalmologist for not having used a proper implant to get a basic correction that brings the eye to just about to 20/20 for distance.

we're talking about an aphakic patient, not a pseudophakic patient. there may be complications preventing the use of an i.o.l.

i would recommend calling the doctor, christosfer, and getting clarification about the strategy for correction and try to learn a bit about the patient's specific history and needs. also, i agree with chip about the v.d. a slight adjustment at that power will give you a significant change.

also, i would recommend farming that job out to a bigger lab so you don't have to worry about absorbing the cost of possible breakage. getting the carrier thickness and curve correct can be a challenge and is critical for the lens to be safe. also you may run into problems blocking it depending on your equipment. you might also look into the possibility of a hyper-aspheric.

**chip anderson** · 09-02-2008, 06:21 AM

As it meanders, this thread is getting a little confusion.
Does the patient need a +25.00 distance or a +25.00 add?
If the former he needs a good, well fitted, well managed PMMA contact lens fitting.
If the latter I can't really concieve of this working at all except as some sort of telecopter or possibly a projection reading devise.

I mean really, a 1" focal length is less than the separation from one eye to the other, just ain't gonna work.

Chip

**EyeFitWell** · 09-02-2008, 12:56 PM

Originally Posted by chip anderson

As it meanders, this thread is getting a little confusion.
Does the patient need a +25.00 distance or a +25.00 add?
If the former he needs a good, well fitted, well managed PMMA contact lens fitting.
If the latter I can't really concieve of this working at all except as some sort of telecopter or possibly a projection reading devise.

I mean really, a 1" focal length is less than the separation from one eye to the other, just ain't gonna work.

Chip

Chip, that's what I was just thinking...+25 distance makes sense, but are we saying this pt needs 25D of magnification to focus from distance to near? I thought that the natural lens only added 2.50 anyway, and I know there are cases when the pt requires an add higher than that, but I've only seen 4.00 at the most.
Secondly, doesn't increasing the near power DECREASE the focal length? Couldn't you (in theory) lower the add power and allow vision more than a couple inches from the face for reading?
I understand aphakia, never worked with it much though. It sounds like more of a low-vision issue than the aphakia...I would think that would require 25 for distance, and still 2.50-4.00 as an add. What am I missing here?

**Ory** · 09-02-2008, 01:50 PM

Sounds like the patient is aphakic, likely congenital and has very poor acuity. No lens will give the patient 20/20. A +25.00D add will give great big magnification right up close and is essentially a microscope. Great for spotting.

**Uncle Fester** · 09-02-2008, 02:02 PM

Originally Posted by Christosfer

In fifteen years I have not had the chance to do an Aphakic lens. So I could use some help. First of all I am concerned that the Doc changed the add from +20 to +25, although her last exam was in 1999.
It looks like she is wearing a curve top of some sort.

Here is the thing that I don't get, she reads at about six inches and I am thinking that another 5.00d is not going to make that better. I don't have much low vision knowledge so I could use some advice here.

Some other questions:
What kind of turnaround time should expect on a lens like this?

Why would someone with an rx like this come in 20 minutes before closing? :hammer:

Coffee Joe's advice is spot on!

You can break the ice in your call to the Doc by asking what vertex distance he keeps his phoroptor.

If she is in a curve top than the add has got to be +2.00. You're only trying to focus the light from the lens to the retina, correct? If it is +20.00 you will be looking at a most unique lens with a segment shelf of extraordinary size although I don't think it could be made and vision wise as others said it just won't work. Don't forget that the thickness of the lens will be affecting the +2.00 add making it a +2.50. Frames that can have the temples either shaped or converted to cable I strongly recommend to this Rx. In fact this is the kind of job that I "take over" the frame selection so I'm all but dictating to her what to get. This is a vision issue and fashion really needs to be in the back seat.

Kind regards.:)

**Christosfer** · 09-02-2008, 03:04 PM

Here is the scoop. Her current glasses look like a round seg of some sort. The add is currently +20.00, and it looks like her distance is perhaps a +4 or 5.00, I haven't looked at her Rx since Friday, Long weekend :).

It does not appear that she has trouble with distance, but she reads like a jeweler looking through his/her eyepiece if you know what I mean. There is definately some special circumstance though I do not yet know what it is. She mentioned going to the University and to this Surgeon next door. However, her last Rx is from 1999!

**Christosfer** · 09-02-2008, 03:06 PM

[quote=coffee j you might also look into the possibility of a hyper-aspheric.[/quote]

I have read here that it can be counter-productive to use Aspheric lenses for Low vision patients because of the reduced magnification.
Is this true?

**coffee joe** · 09-02-2008, 03:26 PM

christosfer, it sounds like maybe the lens you're describing is a lenticular. if i'm correct in that assumption then the +25 would be the aperture of the lens and the +5 would be the carrier portion. as far as hyper-aspherics go, they were introduced to phase our lenticulars. if your patient is already wearing a lenticular though you may want to keep with that since a change would open up the posibility of adaptation problems. for new fits though i do recomend the hypers.

**Uncle Fester** · 09-02-2008, 04:41 PM

This is really interesting. I'm still trying to imagine this lens. Please bear with me.:)

Does she have IOL implants or was she so nearsighted that her crystalline lens was not replaced making her need aphakic glasses?

Does the round seg have a pronounced bubble? I imagine it would look almost like half a marble.

edit-I'm re reading Coffee Joe's above post and it's got to be that.

**Christosfer** · 09-14-2008, 07:55 PM

Originally Posted by Uncle Fester

This is really interesting. I'm still trying to imagine this lens. Please bear with me.:)

Does she have IOL implants or was she so nearsighted that her crystalline lens was not replaced making her need aphakic glasses?

Does the round seg have a pronounced bubble? I imagine it would look almost like half a marble.

edit-I'm re reading Coffee Joe's above post and it's got to be that.

Yes, her reading looked like a shooting marble sticking out of her lens. The doctor did decide to reduce the add to +20, which leaves her with the same rx. I am not sure what her medical backround is, but it must be the case that her crystalline lenses were removed quite some time ago.
What is odd to me is that someone with an rx like this wouldn't take their vision more seriously.
Anywho, I am waiting on the frames to view. I think that when she sees the price she might try walmart.

**Andrew Weiss** · 09-15-2008, 09:25 AM

Originally Posted by Christosfer

Yes, her reading looked like a shooting marble sticking out of her lens. The doctor did decide to reduce the add to +20, which leaves her with the same rx. I am not sure what her medical backround is, but it must be the case that her crystalline lenses were removed quite some time ago.
What is odd to me is that someone with an rx like this wouldn't take their vision more seriously.
Anywho, I am waiting on the frames to view. I think that when she sees the price she might try walmart.

I can't imagine WalMart would be less expensive on a job like this.

And, if she had had her crystalline lens removed and no prosthetic insert, she'd would have had to have been around a -10.00 prior to surgery to only need a +4.00 or +5.00 to get good distance vision.

I strongly second Uncle Fester's advice about frame selection here. And, did you ask the prescribing MD about using B.O. prism for fusion at near? or does the patient really use the reading portion like a jeweler's loop, i.e., one eye at a time?

**drk** · 09-15-2008, 11:53 AM

I would call to clarify. That case is bizarro.

**Jacqui** · 09-15-2008, 12:26 PM

Originally Posted by drk

I would call to clarify. That case is bizarro.

I've mad some really strange lenses in my time, but that is WEIRD !!!

**DragonLensmanWV** · 09-15-2008, 01:31 PM

I did a +20 add round seg once for a low vision patient. He had to hold his head just a couple of inches from what he was reading, but it worked for him. Don't remember what his distance Rx was though.

**Ory** · 09-15-2008, 01:34 PM

If the patient is low vision it makes sense.

Distance is a relatively low power because increasing it will negatively impact the vision. On the other hand, a +4.00 will help even a 20/400 patient peripherally if that is their distance Rx.

A +20.00 (or greater) add will give huge magnification at the expense of visual field. Grab a +20.00 trial lens. Use a lens marker to make a black spot in the centre, about 3-4mm. Hold it right up close and try to read a file through it; don't move your eye, keep fixated on the black spot. See how that amount of mag helps use the peripheral vision for reading?

As to why this is being done binocularly, I really have no clue. There's not a chance they'll be able to fuse those images; that's where spec-mounted telescopes come in!:D