What would you do?

[kcount]

Patient: 49 year old female

complaint: Trouble with dizziness and vertigo. Not seing better with new glasses. "Things are brighter with new Rx but not clear, I get dizzy all the time."

Hx. PTK OS 11/6/2009

Va cc OD 20/30-2
OS 20-50

Va ph cc OD
OS 20/30

Applanation Tonometry
OD 18
OS 17

Wearing Rx: OD +3.50 +2.50 178
OS +1.00 +2.00 060
Add +2.25 OU

Manifest Rx: OD +3.50 +2.50 175 20/30
OS +1.00 +4.00 060 20/25
Add +2.25 J1+

Ophthalmology Exam:

External OU wnl
Lid/Lash Norm OU
Conj. / Sclera White/ Quiet
Cornea PKP, Granular Dyst. OU

Lens 1+ Nuclear Sclerosis


Final Rx:

OD +3.50 +2.50 175 Add +2.25
OS +1.00 +4.00 060 Add +2.25



Two weeks later: Patient still unable to wear glasses without nausea.

[Jeff Trail]

here is one possibility, she is running over a +4.25 imbalance in the 90, any complaint in the reading as well? most time when any one has told me they are getting a dizzy feeling or nausea it will track back to cylinder and axis as the issue.. is she aphakic.. two things I would try with this complaint is occlude each eye and see if the same feelings of dizziness or nausea were felt.. possible go as far as full on patching and let her walk around the store for a bit.... second is trial frame her and see if the problem is really connected to either over refraction of cyl. and or axis..... could also seat them dial in the RX and than neutralize that induced vertical imbalance and see if that is the culprit.. I am going to place my money on a combination of axis and imbalance of power..

Jeff "if ya don't know it make it up as you go" Trail ;)

[uncut]

Hi KC:

My $0.02.

This person is probably neither a head or eye turner, but probably a "searcher" because of reduced acuity(dystrophy). The drastic change in cyl OS is probably giving her more static, than benefit. 2.00D additional cyl is difficult for anyone to deal with in one shot. I could see 0.75 more as being a tolerable amount to adapt to in one Rx change.

If there is no change in index of material, or multifocal design, I would assume base curve couldn't be maintained due to power up OS, but a radical shift in base curve could be an additional aggravation.

The cyl OD could be slightly involved, shift it back to old position.

[kcount]

Update: Rx Made in SV Trivex 48-19 Soft Square Metal Frame. Patient today stated that if she looks straight out VA and vertigo good. On movement Lower left "Waved".

This would be a classic case for a digital lens and it would be interesting to see if the vision would be better, but I'm not so sure it would make an appreciable difference.

[kcount]

Update: Rx Made in SV Trivex 48-19 Soft Square Metal Frame. Patient today stated that if she looks straight out VA and vertigo good. On movement Lower left "Waved".

This would be a classic case for a digital lens and it would be interesting to see if the vision would be better, but I'm not so sure it would make an appreciable difference.


Uncut, It would be interesting to run the numbers again and see what the Horizontal imbalance is. I think I'll do that tomorrow.

[KellyR]

Has the patient worn Trivex before? I have had experiences where patients cannot adapt to poly and problems were eliminated by using CR-39

[scriptfiller]

Kelly R,

Trivex and poly are (optically) two different beasts. Poly has a ABBE value in the low 30's whereas Trivex has an ABBE value in the high 40's. Trivex is the Swiss Army knife of materials it combines thin, lightweight and good optics into one package.

RE the OP

It's got to be the jump in cyl power in the O.S. that's driving her crazy. If it were up to me I would start with a 1 diopter increase and in 3 months come back for the full deal.

[cleyes]

kelly r,

trivex and poly are (optically) two different beasts. Poly has a abbe value in the low 30's whereas trivex has an abbe value in the high 40's. Trivex is the swiss army knife of materials it combines thin, lightweight and good optics into one package.

Re the op

it's got to be the jump in cyl power in the o.s. That's driving her crazy. If it were up to me i would start with a 1 diopter increase and in 3 months come back for the full deal.

ditto

[KellyR]

scriptfiller,
I am aware that Trivex has a better ABBE than poly,(43 vs 30 to be exact) but the huge change in cyl combined with the lower ABBE of Trivex vs CR-39 could also be causing some problems with abberation. When choosing lenses for somewhat complicated RXs like this one, lens material should always be considered.

[Speed]

Ditch the poly.

[Speed]

Edit!
Ditch the poly or trivex. Be sure to AR. Back off the cyl on the OS a bit. (Maybe half the change.)

[Robert Martellaro]

I concur with Speed and Scriptfiller- It may be necessary to reduce OS cyl and/or straighten the axis.

Search "oblique meridional aniseikonia".

http://books.google.com/books?id=qYe...ikonia&f=false

Update: Patient today stated that if she looks straight out VA and vertigo good.

That's good news!

On movement Lower left "Waved".

This might subside after two more weeks. Progress looks good. I'd give it more time before altering the script. Good luck to both of you.

[Craig]

scriptfiller,
I am aware that Trivex has a better ABBE than poly,(43 vs 30 to be exact) but the huge change in cyl combined with the lower ABBE of Trivex vs CR-39 could also be causing some problems with abberation. When choosing lenses for somewhat complicated RXs like this one, lens material should always be considered.

RThis may help folks understand that the ABBE value of Trivex is as good as the human eye need and cannot really be imporved on with a different material. The human eye has an ABBE value of approx. 43 and there is no way they can tell the difference optically between plastic and trivex; they will notice the weight of the cr-39.
This is not a material issue, but an RX issue. You cannot give an extra 2.00D of cyl and expect an instant miracle. It took me years to wear my full 1.50D of cyl.
We always use Trivex as our first choice for all orders and put 85% in them at last tally.

Craig

[Craig]

The edit feature is not working and I cannot clean up my spelling errors.

[Fezz]

The edit feature is not working and I cannot clean up my spelling errors.

It is not working for me either. I tried on my home and work computers. I also tried my iPhone.

NOTHING!

[Craig]

It is not working for me either. I tried on my home and work computers. I also tried my iPhone.

NOTHING!

Why are you home so early? I didn't think a friend of john's would utilize such modern technology as an Iphone. i just got the Ipad as a gift for my birthday; the kids and my wife love it, I could leave it.
Craig

[Robert Martellaro]

The human eye has an ABBE value of approx. 43

Probably closer to 55.

http://docs.google.com/viewer?a=v&q=...qkuGJCzbAhSXLA

I would think that there's an additive or compounding effect between the lateral chromatic aberration (LCA) of the spectacle lens and the eye, and that the threshold of sensitivity will vary greatly between individuals, especially when other aberrations come into play.

[cleyes]

When edit fails, click on "go advanced" , clean up post, then click save.

[drk]

This patient is screwed.

Phototherapeutic Keratectomy, granular corneal dystrophy, cataracts coming on...

This is indeed from anisometropia, and Robert's right, a lot of it is from the oblique axis.

This is really a surgical case, and I'm sure they'll be all over it when time comes, but what to do in the meanwhile?

First of all, the patient needs 1.) correct expectations 2.) hope for the future (come on, cataracts!) 3.) something to get her by, and that's where you come in.

This case will indeed involve modification of the refraction to arrive at a prescription she can wear. This will involve rotating axes towards the horizontal meridian, cutting cyl and prescribing spherical equivalent, and heaven forbid maybe even iseikonic lenses, if all else fails. The trial frame is the friend, here.

For the spectacle correction, all the standard considerations apply; a good lens material, a small ED frame, equal bases and centers.

An RGP contact lens correction can be considered, later.

Glad it's not my patient, K-dog.

[HarryChiling]

Probably closer to 55.

http://docs.google.com/viewer?a=v&q=...qkuGJCzbAhSXLA

I would think that there's an additive or compounding effect between the lateral chromatic aberration (LCA) of the spectacle lens and the eye, and that the threshold of sensitivity will vary greatly between individuals, especially when other aberrations come into play.

Robert,

You're right it is an additive effect.