Anisometropia and PALs

[drk]

Now with customizable progressives available, can we apply it to this small subset of the population?

Currently with traditional progressives, anisometropes will have the usual potential disadvantage of either eye getting a distorted version of the intended design.

They also have a secondary disadvantage of having mismatched distorted versions of the intended design: OD has one "problem" and OS another, making binocularity difficult.

If we use customized progressives for an anisometrope is it safe to say that, regardless of the distance power OD and OS (assume equal adds) the peripheral astigmatism, zone widths, etc. will be equivalent and improve binocular vision?

Or, is there still some residual inequality (other than prism)? And if there is residual inequality, can we "ruin" the better lens' function to match the worse in order to enhance binocularity?

[Bobbi]

Just had similar situation w/pt...I just stepped intot his position at a new clinic and dispensed uniques in trivex with ar, ordered by the former optician...
+3.00 +.75 x 085
-.50 +.50 x 090
2.25 add ou
18 high ou in full metal frame w/ B of 29

pt called three days later complaining of "almost double vision"
first time progressives
stated she played with the nosepads herself to try to fix it



oh yeah...best corrected was OD 20/400+ OS 20/40+


She's coming in Tuesday for me to take a look and probably get her rx rechecked, but in my opinion, not a candidate for progessives, regardless of the design or technology....what do ya'll think?

[sharpstick777]

We have done with the Definity for Anisometropia patients. Just did a +4.75 PD +1.75 OS (+1.75add) and the patient is dancing every time I see her.

Sharpstick

[chip anderson]

Most of the time when a patient has limited visual acuity potential, the patient (not you) is going to see better and be happy with a lined type bifocal.

Chip

[Yeap]

i will manage case like this depend on the distance and near VA on both eye and also very important the dominant eye.

just to share a case that my patient seeing double for the pass 3 years due to the effect of thyroid disease with her multifocal end up she will suppress her left eye which is her non-dominant eye. i just saw her last month for her 1st visit to my practice and now she have right eye multifocal and left eye single vision with near Rx. now she enjoying her glasses for both distance and near. for the multifocal i fit her with SolaOne and she find that the lens is much better than her old lens, Hoya GS.

[DragonLensmanWV]

I once had a lady with about 3D aniso, but her big problem was 5D more oblique cylinder in one eye. She ended up being happiest with a trifocal for her dominant eye and a bifocal for her other.
Strange but true.

[Jacqui]

I can't really say why, but I get a bad feeling about using a progressive with anisometropia. I really think the patient will do better with a lined bifocal or trifocal.

[drk]

You are talking about the nightmare anisometropes and amblyopes--good points, all.

What about, though, the very functional two diopter anisometrope, or the mismatched cylinder axis patient, etc.?

[sharpstick777]

I can't really say why, but I get a bad feeling about using a progressive with anisometropia. I really think the patient will do better with a lined bifocal or trifocal.

I have never had a single Progressive non-adapt with my Anisemotropia patients, but on one occaission I had to bump the reading add in one eye (used +2.25 OD and +2.50 OS) and it improved the "speed to focus". On a couple of occaisions I have had to put a little prism into the lower power eye with post catatact surgery Anisometropes when they had double vision reading but not distance.

I only do about 3 lined lenses a year, we are about 50% Progressive, 50% SV.

Sharpstick

[sharpstick777]

Just had similar situation w/pt...I just stepped intot his position at a new clinic and dispensed uniques in trivex with ar, ordered by the former optician...
+3.00 +.75 x 085
-.50 +.50 x 090
2.25 add ou
18 high ou in full metal frame w/ B of 29

pt called three days later complaining of "almost double vision"
first time progressives stated she played with the nosepads herself to try to fix it oh yeah...best corrected was OD 20/400+ OS 20/40+

She's coming in Tuesday for me to take a look and probably get her rx rechecked, but in my opinion, not a candidate for progessives, regardless of the design or technology....what do ya'll think?

BCVA is terrible OS, and there is no perfect solution for her. It may be in her case a Progressive is not the best choice, but I would not hesitate to try a Definity or Auto II first with a decreased power OD (with Drs permission of course to +2.50 +.75 ) because its seems she is "close" to getting it to work. If you find a power/progressive combo that works for her you will be a hero for life.

With that a DVA that bad there is usually another pathology involved though, and with multiple pathologies I would go straight into a ST-28 especially if she has ARMD. Trivex is a good choice for her though, she needs that extra protection.

Sharpstick

[Darryl Meister]

I'm surprised that somone with 20/400 vision in one eye is complaining of double-vision.

[Bobbi]

I suspect the "almost double" vision is:
1) change in cylinder correction (not verifiable-pt's last pair broke in car accident)- maybe cyl is intolerable for her
2) possibly deeper damage from car accident, I don't believe everyhting has settled down since accident, also
3) patient is on pain meds, which can contribute to blurriness, and if they're really good possibly "almost double" vision
4) patient may just need to feel taken care of by having another check
5) patient has a very real case of buyer's remorse (has sent in significant other to challenge my prices compared to the 'marts in town and accused me of having someone pull back my covers every night...true story)

at any rate, I believe her issues, aside from being monocular, are a large combination of all of the above. Dr. rechecked her, waved off my concerns about progressive designs and changed to plano +2.25add we'll see how she does, she hasn't called me back yet and picked them up monday.

[drk]

I'd think her "almost double vision" is off-center prism-induced diplopia. I'd think the second approach will work well (although taking it to plano was a little nuclear).

I'm guessing she has ARMD with mild cataract OD and mild ARMD OS with pseudophakia OS.

I'm guessing they simply prescribed the refraction OS post-op.

[drk]

Maybe I can clean up my original premise:

Suppose someone has mild anisometropia without amblyopia, let's say:

OD: plano-1.75x 035
OS: plano-1.75x 145
+2.00 add.

If they get conventional progressives, it is my concern that each lens will have dramatic deviation from intended design for a plano/+2.00. The issue in this case will be binocularity for sure, as I assume the corridor, distance, and near zone will be narrowed asymmetrically.

If we go to individualized, then we will get intended design for each eye, but I don't think we can go any further towards helping binocularity in this case.



What about this case, though:
OD: plano
OS: +2.00 DS
+2.00 add?

Assuming that conventional progressives are not close to intended design in this case, if we "widened out" the zones with individualized design, would the left eye still have narrower zones than the right?

Or, would individualization make them both about the same?

And what if OS zones were still narrower than OD despite individualization...could we narrow OD to match OS? (Would we want to?)

[JanMueller]

In my opinion, the most important thing about Anisometropia is to prescribe a PAL with a short corridor. This is a kind of a "natural" slap of that this kind of clients seem to benefit from.
Just had a women with FreeSign Standard corridor, and she was not that happy. O.K. she had a difference of ca. 3.5 dpt (myopic). I then switched her to XS and all Problems where solved. Even with "normal" Patients I am getting used to not always giving them the long corridor lenses even when it would work. I think a 18mm corridor in the most cases is quite ideal. 14-16mm is perfect for Anisometropia because the main Problems is the intermediate. (Please don't blame me on my written English...)

[Darryl Meister]

Another option is to have the optical centers lowered slightly in order to reduce the vertical imbalance at near by tolerating some at distance. However, this may be difficult for many laboratories to calculate nowadays.

[drk]

GT2 3D is slightly softer than either Zeiss Individual or semi-finished GT2 in order to provide even better binocularity. (Softer power gradients result in fewer differences in power, prism, and magnification between corresponding points across the right and left lenses.)

From another thread, Darryl answers my question, here, I believe.

It is safe to conclude that binocularity is improved with less steep power gradients, in the sense that differences in zone width are hidden by wider distribution of aberration.

In other words, an anisometrope would do better in a soft design.

Now, the question is: what individualized lenses have a soft design?:hammer:

[Georg Mayer]

Generally speaking a short progression zone has an advantge versus a long progression zone if the position of the prism refernce point can not be varied in the design. This is particurlaly true in case of higher anisometropia.

However it is ideal if the position of the prism reference point can be altered ( as it is the case with all Rodenstock customized PALs ) to the wearers preference, i.e. to avoid fusion problems due to vertikal imbalances looking at close distance objects. That's in essence the point Darryl made already, trading off imbalances from near to far. Again, in case of higher anisometropia the choice of design should always be the shorter corridor design. We think that a prismatic customized PAL is in this case superior, even to Bifocals.

Georg Mayer
Rodenstock Munich

[drk]

Thank you, Georg.

We're at least aware of the need to minimize prismatic imbalance on downgaze with anisometropes.

In retrospect, what I'm talking about is probably better termed "binocularity".

Combining what I feel is true (softer design is better for binocularity) with the higher, wider near zone, I guess one gets a complete understanding of what the best theoretical lens design would be.