Astigmatism and a Flat Tire?
The last doctor told me my eye with astigmatism was shaped like a football and now you’re telling me it’s a flat tire...
So I have a flat tire:
A flat tire is round on the top and flat on the bottom.
The optical surface of the front of your eye is shaped that way. It is round on the top and flat on the bottom. It is called astigmatism. To prescribe your glasses we leave the round part alone and round out the flat part. That way you can then roll down the road!
A flat tire is round on the top and flat on the bottom.
The optical surface of the front of your eye is shaped that way. It is round on the top and flat on the bottom. It is called astigmatism. To prescribe your glasses we leave the round part alone and round out the flat part. That way you can then roll down the road!
Of course your eyes do not park on the curb so the round part is not always on the top. It can be in any direction. When it is not on top, your glasses can cause distortion at first and you may have to go through an adaption period.
Many compare astigmatism to a football.
Usually the flat tire example gets the idea across better. Yet, since you know about the flat tire, let’s see if the football example will add to the understanding.
Usually the flat tire example gets the idea across better. Yet, since you know about the flat tire, let’s see if the football example will add to the understanding.
You certainly realize a football is shaped differently than a basketball. However, depending how you hold a football, some times it has the same shape and sometimes it doesn’t.
In this picture it doesn’t look anywhere near a basketball. It is closer to the flat part of a flat tire.
In this picture it looks like a basketball. It looks more like the round part of the flat tire.
What does an astigmatism prescription look like?
When you write the prescription for glasses that have astigmatism it is more complicated. Some people recognize the power of glasses that are either nearsighted of farsighted and they only have one number. Some are familiar with over the counter readers that list only one power. So when you ask what is the power of my astigmatism Rx, it gets complicated because it requires two powers and a direction. A farsighted prescription looks like this:
+2.00.
Yet an astigmatism prescription looks like this:
+2.00 -1.00 x 90.
The first number of +2.00 indicates the basic power. The second number of -1.00 indicates the change in curvature from the round side to the flat side. The third number of x90 indicates the direction of the astigmatism
What does an astigmatism prescription look like?
When you write the prescription for glasses that have astigmatism it is more complicated. Some people recognize the power of glasses that are either nearsighted of farsighted and they only have one number. Some are familiar with over the counter readers that list only one power. So when you ask what is the power of my astigmatism Rx, it gets complicated because it requires two powers and a direction. A farsighted prescription looks like this:
+2.00.
Yet an astigmatism prescription looks like this:
+2.00 -1.00 x 90.
The first number of +2.00 indicates the basic power. The second number of -1.00 indicates the change in curvature from the round side to the flat side. The third number of x90 indicates the direction of the astigmatism
You say there may be distortion!
Some times people have difficulty adapting to eyeglasses with flat tires. Lenses actually change your perception of space. Nearsighted lenses move space closer and farsighted lenses move space further away. Most people can adapt to one change in space. Yet, Astigmatism lenses move space in two directions at the same time. The round part of the flat tire doesn’t change space location but the flat part moves space closer. Then depending on the direction of the flat part of your tire, you may feel taller or shorter or objects on your right side may appear to be a different distance than those on the left side. It could even make you dizzy. If that happens don’t panic, it usually adjusts within three days. The distorted images seen in fun houses mirrors look that way because astigmatism is ground into the mirrors.
Some times people have difficulty adapting to eyeglasses with flat tires. Lenses actually change your perception of space. Nearsighted lenses move space closer and farsighted lenses move space further away. Most people can adapt to one change in space. Yet, Astigmatism lenses move space in two directions at the same time. The round part of the flat tire doesn’t change space location but the flat part moves space closer. Then depending on the direction of the flat part of your tire, you may feel taller or shorter or objects on your right side may appear to be a different distance than those on the left side. It could even make you dizzy. If that happens don’t panic, it usually adjusts within three days. The distorted images seen in fun houses mirrors look that way because astigmatism is ground into the mirrors.
What happens if I do get distortion?
First don’t panic. Call for an appointment to double check the fabrication and adjustment of your glasses. We will re- verify the glasses, compare our examination finding to your lab order, and recheck the adjustment. If all is okay, you are now assured your glasses are correct and there is an adjustment to be made by you. Until this point you weren’t sure if something is wrong and weren’t sure if you should join or fight the new glasses. Now you know there isn’t anything wrong and you need to join, not fight them. Yes, that sounds strange but in more than 90% of the cases once you know they are okay you adjust within three days. Don’t go more than three days with your efforts. If there is still distortion, we will schedule a no-cost recheck. It is helpful to run your hand on a flat surface while you look at the surface like a table top or door frame. Bouncing a ball by looking at the ball also helps
First don’t panic. Call for an appointment to double check the fabrication and adjustment of your glasses. We will re- verify the glasses, compare our examination finding to your lab order, and recheck the adjustment. If all is okay, you are now assured your glasses are correct and there is an adjustment to be made by you. Until this point you weren’t sure if something is wrong and weren’t sure if you should join or fight the new glasses. Now you know there isn’t anything wrong and you need to join, not fight them. Yes, that sounds strange but in more than 90% of the cases once you know they are okay you adjust within three days. Don’t go more than three days with your efforts. If there is still distortion, we will schedule a no-cost recheck. It is helpful to run your hand on a flat surface while you look at the surface like a table top or door frame. Bouncing a ball by looking at the ball also helps
Astigmatism contact lenses
Flat tires get complicated in contact lenses. A standard contact lens rotates in a circle as it is worn. However if you have flat tires (astigmatism) the rotation will cause the direction of the flat part to change resulting in blur and distortion. That requires more fitting time and specialized materials. That is why flat tire contact lenses are more expensive.
Flat tires get complicated in contact lenses. A standard contact lens rotates in a circle as it is worn. However if you have flat tires (astigmatism) the rotation will cause the direction of the flat part to change resulting in blur and distortion. That requires more fitting time and specialized materials. That is why flat tire contact lenses are more expensive.