# Thread: What does this even mean?

1. ## What does this even mean?

I have a patient who has be completely stumped.

The patient is a 70 y/o woman who had cataract surgery 4/2021

OMD Post Surgical RX
+0.50 -0.75 x 95 /2.50
+0.75 -1.25 x 75

Patient came to us to fill the prescription using her POF, she's already wearing a Physio Transitions we give her a price, which is as much as a Autograph 2+ Transitions, and she elects to fill it as a Spectrum+ Transitions

2 weeks after dispensing she comes back in because she is complaining that objects are slanting away and that round shapes seems to be oblong. At this point she tells me that she has another pair of glasses from prior to her surgery that she can see pretty well out of that doesn't have that problem they neutralize as:
Pl -0.50 x 90 /2.25
Pl -0.75 x 95
But she also states neither her computer or reading are good through that rx.
We recommend that she has a reexam either at the OMDs office or at our office, she elected to have the exam here.
So, the rx our OD got was:
Pl -0.50 x 90 / 2.50
+0.25 -0.75 x 80
The patient husband picked up the eyeglasses yesterday (because she was a work) the patient called today to say that while the oblong effect is gone, it still looks like object are slanting away.
We're stumped here what do we look at next?

2. I would suspect prism thinning.

3. Is the slanting at all distances? If only noticed at near put some panoscopic tilt to her lens, maybe a little face form.

4. Old glasses are now underplussed so that explains that.

This is a longshot but I think I understand it. It is very mild and shouldn't affect anyone but the princess and the pea.

Do an optical cross for the right eye...it's +0.50 in the vertical meridian and -0.25 in the horizontal with perfect axes. On the optical cross, draw (exaggeratedly) how a circle would be (ever so slightly) distorted by the difference in magnification between the meridians...it would be a slight oval with the longer radius x 90.

Draw it for the left (assume axis 77.5!). You will get an oval a teensy bit longer and skinnier. You will get the long axis at 77.5, which is off-vertical.

Now overlap the two ovals. Notice that at ON PAPER the top of the ovals, the right image is to the left, and the left image is to the right. But now remember that this is your view of her, not her view out, so reverse it. She sees the right image to the right and the left image to the left. That's a form of "uncrossed disparity" that the brain can sense.

Notice at the bottom, the case is reversed. ON PAPER the right image is on the right, the left image is on the left. Her view is right image on the left, left image on the right. That's a form of "crossed disparity" that the brain can sense.

To experience this, look at a close finger and notice a farther out finger is double and wink an eye and you'll see it's uncrossed diplopia. That means when the brain senses an uncrossed disparity it perceives it as "farther out".
Look at a far finger and notice the near finger is double and wink an eye and you'll see it's crossed diplopia. When the brain senses crossed disparity it is perceived as closer.

Applying that to the circles looked at from her perspective, she gets uncrossed disparity at the top of her visual field (perceived farther out), and crossed disparity at the bottom of her visual field (perceived closer in). Therefore she sees things things as farther at the top and closer at the bottom, giving a tilt sensation.

All that to say it's very possible that she has aniseikonic issues. She'll get used to it. But cut her a break: simply cut the cyl 1/2 D OS and move the axis to 90 and see if she notices minimal blur OS but much improved perception (trial frame helps!)

This explains why oblique axes with even low amounts of cyl is a form of anisometropia.

5. Fantastic explanation, DrK

6. Originally Posted by drk
Old glasses are now underplussed so that explains that.

This is a longshot but I think I understand it. It is very mild and shouldn't affect anyone but the princess and the pea.

Do an optical cross for the right eye...it's +0.50 in the vertical meridian and -0.25 in the horizontal with perfect axes. On the optical cross, draw (exaggeratedly) how a circle would be (ever so slightly) distorted by the difference in magnification between the meridians...it would be a slight oval with the longer radius x 90.

Draw it for the left (assume axis 77.5!). You will get an oval a teensy bit longer and skinnier. You will get the long axis at 77.5, which is off-vertical.

Now overlap the two ovals. Notice that at ON PAPER the top of the ovals, the right image is to the left, and the left image is to the right. But now remember that this is your view of her, not her view out, so reverse it. She sees the right image to the right and the left image to the left. That's a form of "uncrossed disparity" that the brain can sense.

Notice at the bottom, the case is reversed. ON PAPER the right image is on the right, the left image is on the left. Her view is right image on the left, left image on the right. That's a form of "crossed disparity" that the brain can sense.

To experience this, look at a close finger and notice a farther out finger is double and wink an eye and you'll see it's uncrossed diplopia. That means when the brain senses an uncrossed disparity it perceives it as "farther out".
Look at a far finger and notice the near finger is double and wink an eye and you'll see it's crossed diplopia. When the brain senses crossed disparity it is perceived as closer.

Applying that to the circles looked at from her perspective, she gets uncrossed disparity at the top of her visual field (perceived farther out), and crossed disparity at the bottom of her visual field (perceived closer in). Therefore she sees things things as farther at the top and closer at the bottom, giving a tilt sensation.

All that to say it's very possible that she has aniseikonic issues. She'll get used to it. But cut her a break: simply cut the cyl 1/2 D OS and move the axis to 90 and see if she notices minimal blur OS but much improved perception (trial frame helps!)

This explains why oblique axes with even low amounts of cyl is a form of anisometropia.
Standing ovation!! Doc - just let me know when you're accepting applications to come work with you. An excellent write up on refractory/perceptual issues many of us see, but can have a difficult time explaining as clearly as you have here. I will bring beer. :D

7. It may not be the cause of this case's problems, though. But it's good stuff anyway.

Thanks.

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