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Ask Dr. A.S. Desai Your Own Question
Dr. A.S. Desai
Dr. A.S. Desai, Board Certified Ophthalmologist
Category: Eye
Satisfied Customers: 2660
Experience:  MS Ophthalmology with 13 years of surgical experience, well versed with all eye diseases.
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I have a prescription of -7.25 sph -0.75 cyl 20.0 axis Can

This answer was rated:

I have a prescription of
-7.25 sph
-0.75 cyl
20.0 axisCan this be transposed/ converted to bring the sph to-7 or below?
Assistant: Have you seen a doctor about this yet? What medications are you taking?
Customer: N/a
Assistant: Anything else in your medical history you think the Doctor should know?
Customer: No

Hello,

Thank you for the question. I am Dr.A.S.Desai, certified ophthalmologist and I look forward to answering this question for you.

May I know why you want to reduce the spherical power to -7.0 or below?

If you have 20/20 vision with the above prescription then it is better to stick on to it.

If you really want the prescription to be sphere -7.0 dioptres, then you can drop the 0.25 D from the sphere and omit the cylinder of -0.75D. However this will drop your vision to below 20/20 and might become 20/40. Only on this condition can the power be reduced.

 

Hope this helps you to take the right decision. Take care.

Do remember to rate this response positively if it was up to your expectation/satisfaction. Please feel free to ask follow up questions if any.

Regards

Dr.A.S.Desai

 

Customer: replied 7 days ago.
There is a offer online for glasses with lenses for £6 but the maximum prescription strength for this offer is -7 sph, I was wanting to know if it’s possible to play around with the cyl and the axis to manipulate the sph but still have a similar prescription. I am unable to afford glasses if I don’t do this as they will be £80

As I have explained earlier, in case you opt for -7.0 sph, it will not give you a very clear vision especially for distance though the near vision might remain good.

Customer: replied 7 days ago.
Ok just once I had a optician ‘transpose’ a prescription to make it look more on the cyl in order to claim the higher rate from the NHS, I just wondered if it was possible to transpose to make the script look less.

Yes, we can transpose . In your case , the 0.25 D sph can be shifted to the cylinder which will change from -0.75 and become -1.25 D cylinder at 20 axis. However one cannot assure that you will accept the prescription once the cylinder increases. It is usually the other way around. Usually we transpose so as to knock off the cylinder .

Customer: replied 7 days ago.
So that would be -7 sph, -1.25 cyl and a axis of 20. Hopefully that would be ok as my current glasses are really old and I can barely see through them but I don’t have money to replace so the £6 offer seems my only option
Customer: replied 7 days ago.
Do you not add 90 degrees to the axis when transposing?

A word of caution here.....adjusting to a higher cylinder would not be easy.

Here we are not actually transposing. We are just readjusting the power between the sphere and cylinder. In actual transposition, yes the cylinder changes the sign and is 90 degrees different.

In actual transposition, the prescription would read-

-7.75D sph +0.75 D 110 axis

But that would not serve the purpose and would increase the sphere to more than -7.0

Customer: replied 7 days ago.
So readjusting the power would cause difficulties in vision until my eyes adjusted to the lenses?

Yes, there are likely to be adjustment problems. Eventually the eyes may adapt but at the cost of slightly compromised vision.

 

Hope this helps you to take the right decision. Take care.

Do remember to rate this response positively if it was up to your expectation/satisfaction. Please feel free to ask follow up questions if any.

Regards

Dr.A.S.Desai

 

Customer: replied 7 days ago.
Worth trying for £6 I can always go back to my current prescription if it causes too many issues, my previous script is -6.75 sph and -0.75 cyl so that’s gotta be a improvement.

Well go ahead in that case. Best wishes

Dr. A.S. Desai and other Eye Specialists are ready to help you