Question
Hi Dr. Margaret,
I am Taymour from Djibouti, will appreciate highly if you could enlighten my path on this very confusing issue.
I bought a new pair of glass and here how things goes.
after testing my eyes with the machine the readind was:
Right Eye:
S: -2.75
C: -0.25
left Eye:
S: -3.25
C: -0.50
now i asked them to make the new glasses with the above reading but howver they took me to do the manual eye test with those Einsteing glasses and the reading was slighlty different for the Right Eye:
S:-3.00
C: -0.75
so i told them we better stick to the one from the machine because the power isn't that high and it reduces from before so better to keep a low power.
I guess to my understanding the confusion is about the "C" which the call it astigmatism.
so now they have make my new pair as:
I am Taymour from Djibouti, will appreciate highly if you could enlighten my path on this very confusing issue.
I bought a new pair of glass and here how things goes.
after testing my eyes with the machine the readind was:
Right Eye:
S: -2.75
C: -0.25
A: 1*
left Eye:
S: -3.25
C: -0.50
A: 1*
i ma putting an asteriks here * because after my glasses are ready they tested to see the glass power and it shows as above so i 'd like to know what's the "A" stand for ? at one point when the A shows 1 as above i asked here how come in my previous glasses it was R:180 and L:179 ? she said if its 1 then that means its 180 so it won't show 180 but rather it'll show 1. I told here if you say so then how come in my old glasses it shows 180 and the new one it shows 1 !!? i told her by right if what u say its correct then it should show 1 in all glass test and NOT 180, she took again the new pair of glass on the machine n did something and surprisingly she make the A: 180 for both eyes!! could it be that she played around the machine? and manually set it to 180 ? and foremost that this A matter ? and doest this bit of unconfortness and blurrness that i feel form my right eye is because of that?
please help me Dr. thanks, ppl in malaysia here wants money only
Taymour HAG - 006
Answer
The "A" in your glasses stands for the "axis" of the astigmatism. Astigmatism is where you have a different power going up and down in your glasses than you do going from side to side. So you have two different Rx's in the same eye. The "S" in the Rx stands for the amount of sphere power, the basic amount of nearsightedness you have. The "C" in your Rx stands for the amount of astigmatism or the difference between the sphere (lowest, basic) power in the glasses and the highest. The "A" does not refer to an amount, but rather a position on a 360 degree circle where the highest power should be placed. However, if you need the maximum power straight up and down, the power at six o'clock will be the same as the power at 12 o'clock, so there is no need to refer to 360 degrees in the prescription, but only 180 = half of the 360 degree circle.
In your case the astigmatism occurs at the three and nine o'clock position. This is referred to as axis 180. However odd it may sound, axis 180 is only one degree away from axis 1. (again because we are only referring to one half of a 360 degree circle. So one degree away from axis 180 on one side is 179 and on the other side, one degree away is axis 1. When making glasses it is considered "ok" to get the axis right within a few degrees because the manufacturing process is not really all that precise. So if your Rx was for 180, it would be ok for them to give you glasses that read axis 177, 178, 179, 180, 1, 2, or 3. (If you had a really lot of astigmatism, then it would have to be either 179, 180 or 1) Then the machines that read the glasses have a small amount of error built into them so when you read a pair of glasses you could very easily get a reading of axis 180 one time and axis 1 the next time on the same pair of glasses. This is really not the problem it sounds like it would be. So, to answer your question, NO - the difference between axis 180 and axis 1 does not matter much and is not likely the cause of any problems.
Now, if you are having problems with your new glasses and the right eye is blurry, you should go back where you got them and tell them. I am not so sure what you mean by the testing with the machine. Here in the US the machines are used mainly for screening - to give the doctor a starting point from which to begin the manual testing, which is considered more accurate. We never prescribe off the results from the machine, but things may be different where you are. Nonetheless, if you are having a problem with the glasses, you should go to the people who prescribed them to straighten it out.
Good luck resolving this problem.
