We’re gonna explain and answer the question ‘what is astigmatism’ in this post and video.
I’ll explain and cover the following:
- What’s Astigmatism
- How it affects your vision
- How we prescribe corrective lenses for it
Todays Peace Of Mind Point is…
- Astigmatism is not a disease – normal part of why people wear glasses
- It’s common – In my experience, more people have astigmatism to some degree than those that don’t
That should already put your mind at ease about having astigmatism… So let’s get to step one:
1. What is astigmatism:
- An error in the curvature of the cornea that leads to your cornea having a steeper curve along one direction and flatter curve along the other curve at 90 degrees to it.
- So rather than being spherical in shape, it is now irregular like a rugby ball or American football.
- Because you have this difference in curvature, your eye now focuses two points at the back of the eye instead of just one like in a spherical eye that doesn’t have astigmatism which causes the problems you experience with astigmatism stretches out the image you see. Leading to the distortion forming nature of astigmatism. This error in curvature develops on its own from a young age or later in life. It doesn’t follow a specific pattern of deterioration over the years and can get better as well as get worse like nearsightedness and farsightedness.
- You can find a further explanation on the NHS website.
2. How it affects your vision
- It adds more distortion to your vision rather than just blur like nearsightedness and farsightedness.
- Straight lines may distort making it hard to tell certain letters from the other.
- You may experience tired eyes for reading and computer use.
If you’re not sure if you have astigmatisms – Find a copy of your prescription. If it has numbers in the ‘Cyl’ and ‘Axis’ box, then you do.
3. How we prescribe corrective lenses for astigmatism:
In your glasses prescription:
- The eye with no astigmatism only requires one spherical power because that power is the same in all directions of curvature on the cornea. Your glasses prescription may appear as one number in the sphere.
- The eye with astigmatism needs more information – and what we are doing here is making sure that whoever makes up your glasses knows exactly which direction on the cornea surface is flatter and which is steeper. That’s why we now require the additional information of the Cyl and axis for the astigmatic eye. When we correct astigmatism we need to add an additional power called the cylindrical power on top of the sphere we had already. However so we don’t end up having a combined power in all directions again, the cylinder has an axis which is a direction along which there is zero Cylinder power, so that when you combine the sphere and Cyl in this particular direction only the sphere has an effect. During your eye examination, your optometrist will show you a target on the eye test chart that may look like rings, a dial, or even spots in order to fine-tune exactly where your axis needs to be. So, for example, it maybe 90, 45, or any number between 0-180 degrees.
Glasses aren’t the only ways to correct astigmatism…
- Glasses
- Contact lenses – restrictions apply as to how high or multifocal
- Laser correction up to about 6D
Hopefully, that has answered the question of what eye astigmatism is for you. If you have any questions of comments, please leave them below.
Todays Question for you: Do you know if you have astigmatism if so what’s your Cyl power? Let me know in the comment section below.
