Prescription confusion

[Lisa Nixon]

Picked up my new glasses today and everything was blurred! Briefly both eyes have been grafted and this was my first attempt at correction for the Right eye, left doing ok which is why I am confused as already wearing glasses for left eye. Having a problem with Right eye in that when I am able to read well from the chart when looking elsewhere everything is tilted at a 30 degree angle. My local optician suggested easing the prescrition for the Right eye as it may ease the tilting. But he seems to have changed loads from the hospital prescription as follows:

Hospital: Right Eye: Sph: -3.00; Cyl: +5.25; Axis 60. Left: Sph: -3.50; Cyl: +4.25; axis: 130

Today: Right Eye: Sph: +1.50; Cyl: -3.00; Axis 42. Left: Sph: + 0.50; Cyl: -5.00; axis 55

* the Cyl on Right eye he reduced from - 5.00 to ease the tilting which I understand. But I don't understand why pluses have changed to minuses!

To add a little more confusion the current prescription in my left eye is +6.00 which is giving me good vision, can't understand why Hospital reduced it.

Quite a difference! I'm going back next week and am due back at Eye Hospital in December. I am baffled!

[Andrew MacLean]

I am baffled!

Me too! I am sure that one of the optoms will be able to make sense of all this: but if not, please let us know what the explanation is from the hospital.

My "cyl" number varied between plusses and minuses. This was explained to me as being due to the asymmetric healing of my graft causing the astigmatism to vary wildly. Your explanation may be the same, or indeed it may be different

All the best

Andrew

[helen]

hi guys,
this is my first post on here, i'm an optometrist and found the forum as i have a patient who is recently diagnosed with keratoconus and was telling me all about C3-R, and so i've been researching it to try and help him understand the procedure and risks etc.

I saw your post and should be able to help you become less baffled!

Prescriptions are standardised in the way that they are written to avoid confusion, but there are two main ways of writing them, both of which mean the same. One is 'plus-cyl', one is 'minus-cyl'. Optometrists and all in the optical profession regularly convert from one to the other as some optoms work in plus, others in minus, and prescription houses tend to work in plus. contact lens manufacturers always work in minus.

It's difficult to explain how to convert from one to the other by writing here, but i'll give an example.
R -1.50/-0.50x150 is the same as R -2.00/+0.50x60. (we write the sphere first, then the cylinder after a '/', the the axis after a 'x')

For your prescription, to compare results from the hospital and optician, you need to convert them into the same, either plus or minus.
So: Hospital R -3.00/+5.25x60 L -3.50/+4.25x130

Optician R -1.50/+3.00x132 L -4.50/+5.00x145

Yes, this is still a big change, but less than it looked before, when the opticians prescription was written in minus-cyl! The problem seems to be the axis in the right eye, have you copied it into here correctly? A swing from 60 to 132 would be very difficult to get used to. Definitely go back to the optician.

I hope i've helped here and not confused you further. How many optometrists actually post on this forum? If i can help any further, let me know

Helen

[Andrew MacLean]

Helen!

It is always good to welcome another optometrist to our little community!

Thank you for the very lucid explanation.

Yours aye

Andrew

[Lynn White]

Helen!

Welcome to the boards and thanks for diving in and trying to explain transposition!

Lisa - like Helen.. I am wondering about the changes in the right eye. How long was it between prescriptions? Its not surprising you are having difficulties with that kind of change in the axis of your astigmatism... but it can happen! As Helen has shown, the actual prescription differences are not that great once you get them into the same format.

Helen - there are a few of us that post here regularly and if you look at http://www.keratoconus-group.org.uk/optoms/index.php
you will find a list I helped organise of KC friendly optoms. Mostly these are professionals who fit KC lenses but can also include optoms who are willing to go that extra mile for KC patients, If you are interested in being listed please let me know. We also have a professionals forum on here though it is not much used as yet!

Thank you for your contribution!

Lynn

[GarethB]

Lisa,

With glasses, I can get good vision, but see double so the right lens was backed off.

It has taken 3 - 6 months to get used to the glasses where I feel I can up the prescription to get good vision in the right eye too.

However while taking part in some research for a new type of soft lens, the machine suggested I needed prism adding which has never been mentioned before.

At the next lens trial we intend to investigate this further for glasses as the machine thinks I should get pretty much 6/6 with glasses, RGP's and both types of soft lenses the company is researching!

[Andrew MacLean]

Would it be possible to wear a soft lens without any prism, and glasses over the lens? Or, would that just add complications to an already complicated prescription?

Andrew

[Lisa Nixon]

Thanks everyone, I was back at the Opticians today and we're trying another prescription, lenses for glasses should be ready to try next week. I think it's a case of just trying them out. I'm not known for my patience and I was so disappointed not to be able to see a little better with prescription in the right eye - I've had a plano lens in my glasses since graft Nov 05. My son who also has KC started wearing hard lenses this week. He's struggling to get them out but is managing to wear them for about 4 hours a day. He's really pleased with the vision, made a big difference