What do the numbers on the side of my contact lens box mean? what number on the 20/20 scale am i??

Question

ok my box says

BC= 8.2

DIA= 14.2

PWR= -3.75

what do these numbers mean???

how do these compare to the 20/20 scale?

Answer 1

No one can determine your visual acuity with or without lenses from the information about your lenses.

Answer 2

They don't compare to the 20/20 scale at all. We can't tell what the 20/20 value may have been just by knowing the power of the contacts.

You may have a 0.50 or even 0.75 astigmatism correction needed that doesn't show up in the contact prescription, and that could throw estimates of the 20/20 value way off.

The letters you can see on the eyechart are a complete different measurement than the power you need in your lenses.

The 8.2 is the Base curve of your lenses, the 14.2 is the diameter of the lenses, and the - 3.75 is the power of the lenses...that's what those numbers mean.

Answer 3

Well none of them really refer to the 20/20 you mention but there is one clue.

The first measurement is merely the base curve of the contact lens.  8.2 refers only to the size of the eye for which the lens will made.

The second number is the actual size across the lens. 14.2 means fourteen.2 millimetres across. Lenses are usually from 13 mm to 155 mm across. Yours is quite common.

Now the 3rd measurement (the clue) means the power of your lens corrects an amount of myopia (short sightedness)  of  3¾ dioptres.  (dioptres is just another unit of measurement like an ounce or a tsp or a ml).

But the clue is that to require a -3.75 power lens your vision would be about 20/160 or maybe 20/200 instead ot eh 20/20 which means perfect.  The higher the bottom number the worse a person's vision is.  (an example: if a person is 20/400 and it can't be corrected he/she is called "legally blind).

Lucky for you, that -3.75 makes your eyes 20/20 and you are as good as an army sniper or an aiplane pilot.

You've asked a good question.  The amazing thing is that you and I both require a -.375 lens!

RWM (I am a reitred eye doc)