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Thursday, November 14, 2013

Contact Lens Prescription vs. Spectacle Prescription


Contact Lens Prescription vs. Spectacle Prescription 

Contact lens prescription does differ from spectacle prescription, mainly due to the distance between the spectacle and your eyes.
For those with spectacle prescription less than -4.00 D, the difference is insignificant. Patients can choose to wear either the same prescription or slightly lower. Spectacle prescription of -4.00D above, the difference with contact lens prescription will become more significant.
The chart below, is a conversion chart of spectacle prescription to contact lens prescription.
(-) Minus prescription is refer for short sighted or myopia. (+) Plus precription is refer for long sighted or hyperopia.
Besides that, a simple calculation can be done to determine your contact lens prescription (as the diagram below)
_________________from this part, it is my opinion _______________

What if the prescription you are looking for is not available?

1) Try to keep the left-right eye balance 

For example, I am shortsighted and have a left eye spectacle prescription of -6.00, which according to the chart, it is -5.62, my right eye is -5.25, according to the chart I need -5.00. 

I would like to keep my left - right eye difference ( which is now by a 0.75 difference) 
So I choose  -5.75 for my left, and -5.00 for my right. 

2) Try to choose the power closest to your prescribed power. 

So some contact brands does not have -5.75 prescriptions. They only have -5.50 or -6.00. 
So I decide to go with -5.50 instead of -6.00, because my real prescription according to chart is -5.62 (closer to -5.50 an further to -6.00)

3) Go with your feeling. 
Sometimes you just need to try to know which one is better. Just try and feel it out. Order both prescriptions and try them out for a day. 

Hope this helps and Good Luck!