Astigmatism obscures a person’s vision due to an eye shape abnormality. The eye is oval-shaped, which causes light to focus on two points on the retina, rather than on one. Astigmatism glasses correct for this using an irregularly shaped lens to smooth out abnormalities on the eye. Different vision conditions allow for different types of astigmatism glasses. These include glasses for astigmatism alone or for augmented vision problems, such as myopia astigmatism, hypermetropia, or presbyopia.
When a person gets his spherocylinder prescription from an optician, he gets three pairs of numbers: bullet, cylinder, and axis. “Sphere” indicates the degree to which he is nearsighted or farsighted, while “cylinder” indicates astigmatism. Patients with abnormal cylinder measurements have an irregularly shaped lens or cornea. “Axis” refers to the location of the irregularity that causes astigmatism. Based on these figures, the optician can determine exactly what kind of astigmatism glasses the patient needs.
People who suffer from astigmatism without any other eye problem can greatly benefit from glasses with toric lenses. The lenses of astigmatism glasses curve more in one area than in another, relative to location, degree of irregularity in the eye. This offsets the curve of the eye and gives light to focus on a single point in the retina, restoring normal vision.
If the patient suffers from myopia or myopia, toric lenses may be aggravated by concave lenses. This allows for both issues to be resolved through one pair of astigmatism glasses. The concave lenses adjust for myopia, while the toric lenses raise the issue of astigmatism. Similarly, people with both myopia, or myopia and astigmatism can benefit from convex lenses enhanced by toric ones.
Astigmatism glasses can also be made for those who suffer from presbyopia, or blurred vision near objects. Bifocal glasses, which adjust vision for both near and far objects, can be combined with toric lenses. Reading glasses can also be adjusted in the same way.
Although astigmatism glasses do provide clearer vision, they do not cure a person of astigmatism. They are also less effective in dealing with severe cases of mixed astigmatism, where the two irregular curves on the eyeball are not perpendicular to each other. The only known treatment for astigmatism to date is laser eye surgery, which has less predictable results. The added risk makes most people who have astigmatism opt for dealing with the condition with astigmatism glasses or contact lenses.
- An eye exam by an optician can help a patient decide what kind of glasses she needs.
- Astigmatism is caused by an irregularly shaped cornea.
- Routine eye exams can detect vision or eye problems – such as astigmatism – early.
- People with an astigmatism may benefit from glasses with toric lenses.
- A normal eye and one with astigmatism.
- Possible side effects of laser eye surgery can cause patients to choose astigmatism glasses.