In particular, the CYL and AXIS components of your prescription relate to the level of astigmatism in your eyes, a refractive error that means the front surface of one eye isn't completely round. This can cause problems affecting focus, and should be corrected to provide improved vision.
The axis number helps your eye care provider to know the direction in which they should position a cylindrical power in the lenses of your glass.
Wearing an incorrect cylinder axis will not do any damage to your eyes. Switching between two pairs of eyeglasses with different axes will not do any damage to your eyes either. You might, however, notice that your vision is a bit sharper with one pair than with the other. Or not, if the cylinder power is low.
If you compare your current prescription to an older one you may notice that your AXIS and CYL measurements have changed slightly. This is not uncommon, as eyesight can undergo several changes throughout one person's lifetime.
When the axis of the cyl changes, it simply means that the front shape of your eye has changed. A small change in this shape can often give a larger change in axis, so this is nothing to be concerned about, providing your eyes are healthy. It may even occur over what seems like a short period of time.
Will astigmatism get worse if my glasses prescription is wrong? Wearing glasses can't make astigmatism worse, even if they are the wrong prescription. Astigmatism is caused by the shape of the eye's cornea or lens, and glasses can't change those.
Wearing the Wrong Prescription Long-Term
There isn't a risk of long-term eye damage in most adults with stabilized vision. But, you can still experience symptoms affecting vision and comfort. Wearing a prescription that is too weak or too strong can cause: Blurry vision.
Astigmatism frequently worsens with age. Your cornea can become more irregular due to pressure from your eyelids as they lose muscle tone. Astigmatism generally stays stable until your turn 50. After then, your lens curvature progressively worsens each decade.
What is the normal eye SPH, CYL, and Axis value? Normal eyes would typically have about 0.50 dioptres of negative cylinder or cyl power at an axis number of 180. Typically, most people have between 0.5 to 0.75 dioptres of astigmatism and won't need contact lenses or glasses to see clearly.
Simply put, if your prescription is -2.5 or lower, this means that you are legally blind. Visual acuity of -2.5 is equivalent to 20/200 vision.
Axis: The Axis number describes the position of the Astigmatism in your eye. This number shows the direction the eye doctor needs to position any cylindrical power in your lenses (required for Astigmatism only).
Irregular astigmatism will look like an asymmetric bowtie pattern on a corneal topography or Pentacam. One side of of the bowtie is flatter and the other side is steeper. Irregular astigmatism cannot be fully corrected with glasses, and sometimes not with soft contact lenses.
It takes quite a time especially with astigmatism, it can take 3 to 4 days. It can go on for a week or 5 to 6 days if you have moderate or severe astigmatism.
Usually astigmatism above 1 degree causes much visual disturbance. If your vision is affected a lot, you should wear glasses to help your eyes not have to adjust too much. For people with low or low myopia, if eye fatigue and dry eyes do not appear but can still see clearly, they do not need to wear glasses regularly.
When your prescription feels too strong, you might experience headaches, nausea, and eye strain, among other things. It might not be clear why your prescription feels wrong, but it doesn't take long to notice something's off.
Astigmatism is extremely common – many people have some degree of astigmatism. For the majority of people, mild astigmatism does not cause significant vision changes and therefore does not need correction. However, when astigmatism causes blurred or distorted vision, correction is necessary.
Most people do not have perfectly round eyes – they may have up to . 75 diopters of astigmatism, and this is considered normal and will likely not require correction. Between . 75 and 2 diopters is considered mild astigmatism.
A minor astigmatism may not cause any vision problems at all, but a significant astigmatism needs to be corrected. Having an astigmatism may complicate your prescription just a bit, but it won't prevent you from getting the type of corrective lens that fits your lifestyle.
It is normal and common to have a different axis in each eye.
An eye axis defines the lens meridian. Meridians of an eye are calculated by using a superimposed protractor scale which is visually placed in front of the eye.
Small changes to the shape of your cornea can often cause large changes in the axis measurement, although these are rare. If the axis has changed by more than 90 degrees, you may wish to clarify this with our eye doctor, as a variation this large is quite unusual.
AXIS refers to the angle of the astigmatism in your eye and has nothing to do with the severity of your prescription. These digits can be anywhere between 0 and 180 degrees such as 020, 090, 120 or 170 etc. In some instances, your optometrist may have written your CYL and AXIS freehand which can be separated by an “X”.
Axis – The third number indicates the direction of your astigmatism. For example, an axis of 180 degrees means the astigmatism is horizontal. If your prescription doesn't have a second or third number, you most likely don't have astigmatism.