Double vision issues

[Eyedentity3]

Ok I had this patient come in on Saturday that has me scratching my head. For starters here is the script.

OD +1.75 -3.25 x 002 PD28.5
OS +1.75 -3.00 x 172 PD27.0
+2.50 OU
19mm seg OU
She was put into a Zeiss GT2 3DV which means it is a compensated RX :

OD +1.67 -3.08 x 002
+2.41
Prism 0.77 @271
OS +1.69 -2.84 172
Prism 0.77 @ 270
+2.43

Ok here is the issue we made two pairs for the patient this set and also a set of Hoya tact EP40. In the Zeiss pair distance is fine but while reading she is having double vision issues. In the tact no double vision problem exist. The fit is just fine, PD's and seg are right where they are supposed to be. Both sets of lenses are 1.60 with A/R (Purecoat & EX3 respectively), 4.25 base. The Zeiss is a drillmount with polished edges. The Tact is a hide-a-bevel. If I am missing any info that would be helpful let me know.

I am thinking the compensated RX is causing the issues, but I'm not sure. Guy's and Gals thank you for being such a great resource.

Also, here is the previous script:

+1.50 -3.25 x179
+1.50 -3.25 x174
+2.50 OU

[chip anderson]

Is the vertical center "right where it's supposed to be?" Is material poly?

[Robert Martellaro]

I am thinking the compensated RX is causing the issues, but I'm not sure.

Extremely unlikely. Is the diplopia horizontal, vertical or oblique? Hard to imagine how you can induce intractable diplopia without a grevious error in prism thinning, inset, or some other major paramater. Maybe a vertical phoria on the downgaze only (might not show up on the comp glasses with more plus higher in the lens, and maybe by a shorter corridor in the old eyeglasses)? Call the prescriber if the optics are squeaky-clean.

[Arsenal]

Are the lenses aligned with each other properly? I've seen this issue before with lenses, especially in drill mounts, that are not on the same plane.

[Eyedentity3]

Everything seems to be lined up nicely. The material would be 1.60 hi-index. The diplopia is horziontal. Thank you for getting back to me.

[Jubilee]

I have seen a few patients who have either no convergence, or a larger compared to the norm, experience this issue. With the tact being an occupational style lens, the corridor is a lot larger, and more forgiving on down gaze. I suspect Robert is right in that this may be a phoria issue.

[Robert Martellaro]

Are the lenses aligned with each other properly? I've seen this issue before with lenses, especially in drill mounts, that are not on the same plane.

X-ing?

Everything seems to be lined up nicely. The material would be 1.60 hi-index. The diplopia is horziontal. Thank you for getting back to me.

Your welcome. I can't remember anyone with healthy eyes complain of diplopia under these circumstances, except for the very first few minutes of wear. Maybe she's exophoric? Try a hand held trial lens (prism). Is the fitting point center pupil? What was the old PAL design? I've been getting a lot these (vision anomalies) lately- maybe the two full moons last month are catching up with us?

[optical24/7]

Horizontal; Get a layout chart and precisely as you can mark your 180 engravings. Then put a *dot* on the DRP, PRP and center of near verification. Check for horizontal prism at each location. If it progressively increases as you go down the lens, the umbilic may have been inset/outset too much. (fabrication error).

[sharpstick777]

Robert is correct. The issue is with the old pair having too much unwanted prism, either due to too much prism thinning or a surfacing error. look at the prism in the near portion of the old pair, old pd, and I will bet you will find there was a mistake and your patient has compensated. That being said, the GT2-3D is a great lens, but with a narrow reading zone.

Extremely unlikely. Is the diplopia horizontal, vertical or oblique? Hard to imagine how you can induce intractable diplopia without a grevious error in prism thinning, inset, or some other major paramater. Maybe a vertical phoria on the downgaze only (might not show up on the comp glasses with more plus higher in the lens, and maybe by a shorter corridor in the old eyeglasses)? Call the prescriber if the optics are squeaky-clean.

[sharpstick777]

Your welcome. I can't remember anyone with healthy eyes complain of diplopia under these circumstances, except for the very first few minutes of wear. Maybe she's exophoric? Try a hand held trial lens (prism). Is the fitting point center pupil? What was the old PAL design? I've been getting a lot these (vision anomalies) lately- maybe the two full moons last month are catching up with us?

I do see it after Cataract surgery on occaision, esp with previsous hyperopes who are post surgically now slight myopes.

[optical24/7]

The issue is with the old pair having too much unwanted prism, either due to too much prism thinning or a surfacing error. look at the prism in the near portion of the old pair, old pd, and I will bet you will find there was a mistake and your patient has compensated. That being said, the GT2-3D is a great lens, but with a narrow reading zone.

I wouldn't assume the old pair were made incorrectly. There should have been a complaint on pick-up of them back then. Prism thinning (shouldn't) have anything to do with horizontal diplopia since it's a vertical/cosmetic compensation. The most likely suspect is the corridor placement. If it were a simple prismatic error in fabrication, it should show up it the distance area too.

If the diplopia is at near only, horizontal, a simple check at the NRP should show unwanted in/out prism.

Most likely it's a fabrication issue.

[sharpstick777]

Prism thinning can create diplopia is some patients because even the though prism is balance (not effective binocular vision) it still impacts the muscles, just equally. However, reduce prism (or prism thinning) and its the same as carrying a heavy backpack, and now setting it down. You feel light and its hard to walk straight. Muscle memory has changed. It can take awhile for eyes to retrack after that weight has lifted, to restore muscle memory.

I wouldn't assume the old pair were made incorrectly. There should have been a complaint on pick-up of them back then. Prism thinning (shouldn't) have anything to do with horizontal diplopia since it's a vertical/cosmetic compensation. The most likely suspect is the corridor placement. If it were a simple prismatic error in fabrication, it should show up it the distance area too.

If the diplopia is at near only, horizontal, a simple check at the NRP should show unwanted in/out prism.

Most likely it's a fabrication issue.

[Robert Martellaro]

Yoked prism can influence convergence, and possibly cause fatigue, but not diplopia. I'm guessing that this is a noncomitant deviation that didn't show up with the old glasses because the old PAL design had a shorter/faster power profile.

Diplopia is a serious concern. Get the doctor involved if this isn't resolved in a reasonable amount of time (weeks, not months).

[sharpstick777]

I am referring to post cataract patients who, post surgery, experience effective near vision convergence disorder. Although their RX is dramatically improved, they experience double vision for non-neurological reasons usually in the reading only, but I have seen distance as well. Since the visual system has been tested to only tolerate about 2 D of yoked prism well, any prism more than this has the potential for non-neurological effective diplopia because progressive create effective prism away from ground OC. Since most people experience the onset of this gradually, they have adapted to it. However, post surgically, its all taken away at once. I see mostly in it patients who where spherically +-4 or more, then almost plano after surgery. I also see it in lower powers where the post surgical result is anisometropic, where previously they were either fully hyperopic or myopic. There is a lot of prism off center in a high power progressive lens that long time progressive wearers have have adapted to. If you take it away in one day, the muscles require time to adapt in some cases.

Yoked prism can influence convergence, and possibly cause fatigue, but not diplopia. I'm guessing that this is a noncomitant deviation that didn't show up with the old glasses because the old PAL design had a shorter/faster power profile.

Diplopia is a serious concern. Get the doctor involved if this isn't resolved in a reasonable amount of time (weeks, not months).

[optical24/7]

Prism thinning can create diplopia is some patients because even the though prism is balance (not effective binocular vision) it still impacts the muscles, just equally. However, reduce prism (or prism thinning) and its the same as carrying a heavy backpack, and now setting it down. You feel light and its hard to walk straight. Muscle memory has changed. It can take awhile for eyes to retrack after that weight has lifted, to restore muscle memory.

Sharp, I'm still trying to grasp how (vertical) prism thinning can effect horizontal diplopia (sans fabrication error) Can you elaborate?