long term options, mono pseudoaphakic

[Dave Nelson]

I have a client who is monocular pseudoaphakic, secondary to trauma. (hockey stick, how Canadian) He is a young guy, moderate/high myope. The surgeon very wisely, left him myopic in the injured eye, thus avoiding a lifetime of imbalance issues. He presented with a new rx in which the prescriber wrote a full distance correction for both eyes. Since he has no accomodation in the implanted eye, and full accomodation in the normal eye, it presents a number of ways to proceed. He is resistant to a multifocal of any kind, including a progressive. At near, he tends to suppress the presbyopic eye, but when corrected for near, he is able to achieve convergence and stereopsis. In the end, I continued with what he has been doing for 2 years, and is quite happy with.I simply reduced the dist correction in the injured eye by 1.25 (monovision, if you will) and continued on. I have to wonder if this is really the best for him, though, as he will use a progressive if I insist on it. Long term, I am a bit concerned about maintaining convergence if the stimulus is reduced. What are the short and long term options for this patient? How would you proceed?

[Darryl Meister]

A talk with the original prescriber may be in order, and I'm sure there are a few clinicians on OptiBoard who are considerably more knowledgeable about the potential consequences of these treatment plans than I am. That said, binocular vision at near is more of a luxury than a necessity for most people. While I'm sure binocular vision improves reading efficiency to some extent, not many individuals routinely require accurate depth perception at near. (Though it may be interesting to determine at what distance -- if any -- his stereopsis actually breaks down or whether it's simply a gradual reduction.)

I also don't know that you would need to worry about his ability to maintain convergence either, especially at this point in his life, barring any disorders of accommodative convergence. Once his visual system exerts accommodation in the phakic eye, his eyes will continue to converge as part of the near synkinetic reflex. This is particularly for near objects, which already illicit some degree of "proximal" convergence. Though that's not to say that a long-term fixation disparity couldn't result in some sort of anomalous retinal correspondence or some other adaptive phenomenon. But that stuff certainly isn't my forte.

[chip anderson]

Just my opinion but monovision is never best for anyone. Just easier to do than bifocal contacts.

[Darryl Meister]

But keep in mind that he is only "monovision" at near. And I don't know that bifocal contacts would give him noticeably better vision at near than his current accommodative faculties in his one phakic eye.

[chip anderson]

Another cheap alternative if he has things that require reading for long periods of time is an reading correction in the pseudophakic eye and his usual distance in the phakic eye.

Chip

[Dave Nelson]

Thats interesting, Chip. Would he be better with dist in one eye and near in the other, so one eye is accomodating and one not, or near in both eyes so both eyes are "at rest." At the present, he uses, and wishes to continue using single vision spectacles- thats why I tweaked the post-op eye for half his near correction. He likes that set-up and it works for him, but I want to be sure my long term game-plan is the best for him. He's 10 years away from being a presbyope. Thanks.

[chip anderson]

Dave:

That pseudophakic eye ain't gonna accomodate, ever. As long as the phakic eye can accomodate and keep up with the near corrected eye for intense reading, why not let him use both? Then you can slowly add an add when he becomes presbyoptic in the phakic eye.

Hell, he might even be able to have stereopsis at near for fine work, not to mention an ignorable blind spot (optic nerve) as the two eyes would over lap this. There are quite a few senario's where this might be beneficial. You could even save him a finger or two when he works on his car.

Chip

Many people prefer things because they have never had first hand experience with the alternatives (like the +2.75 progressive who has no idea how much more he would see with a lined bifocal). Get out a trial set, a trial frame and let the boy see what the result would be when you achieve image/distance ballance, no charge. Then he will be "qualified to say no."

Chip :cheers:

[Robert Martellaro]

Dave,

If it was my eyes, I would want uncompromised distance vision, although I might play around with a little extra plus (+.25 or +.50) over the pseudophakic eye to help with the mid-distance. I would try a PAL, and if you do add some plus on the distance you can cut the add porportionately for reduced dynamics and an easier adaptation. Alternatively, separate SV readers for extended close tasks might be preferred by some folks.

However,

Many people prefer things because they have never had first hand experience with the alternatives (like the +2.75 progressive who has no idea how much more he would see with a lined bifocal). Get out a trial set, a trial frame and let the boy see what the result would be when you achieve image/distance ballance, no charge. Then he will be "qualified to say no."

is awfully good advice because everyone is different, and allows the client to experience the different possibilities first hand.

Regards,

[drk]

I might be able to help, if I get these assumptions confirmed:

1.) You have him with spectacle monovision, +1.25 D overplussed in the (dominant?) pseudophakic eye. You have him full distance in the fellow eye.

2.) You mention some tendency for convergence insufficiency and suppression in the non-operated eye, right?

I think you are saying that, when he is measured habitually (which in his case is spectacle monovision) you (I assume) measure reduced convergence and suppression in the non-operated eye. If so, this is completely normal, as he is blurry up close in the non-operated eye and it would reduce the stereoacuity measurement. I don't believe this is sufficient to affect convergence, though, as that is driven by more "global" retinal processes than foveal vision.

Does this guy have a real binocular vision problem? You'd have to measure him with full correction distance and near to make it valid. I'm assuming not.

3.) I would think that you have had problems with adaptation to progressives because you are trying to get him to an immediate +2.50 add, due to the pseudophakia. Obviously, this is difficult.

4.) Assuming the guy is 40-something and is an emerging presbyope, the simplest solution I see is to go full distance, but use the add power that the non-operated eye calls for, plus maybe +0.25-+0.50. That should ease adaptation, nicely.

5.) Even if you continue with monovision spectacles, you will not cause long-term convergence problems that couldn't be easily remedied.

Good to have a refracting optician question.

Advice: try to classify patients by their condition, example: monocular aphake, or convergence insufficient, or strabismic amblyope, or whatever. Then you can learn about the condition, and generalize to each individual that has the diagnosis.