What is Cylinder (CYL)?
- Definition: Cylinder (CYL) in an eyeglass prescription refers to the lens power required to correct astigmatism. Astigmatism is caused by an irregular shape of the cornea or lens of the eye, leading to improper focusing of light on the retina.
- Correction of Astigmatism: The CYL value indicates how much lens power is needed to correct this irregular focus. This value can be either positive or negative, depending on the type of astigmatism.
Interpreting CYL Values
- Example Values: For instance, if the prescription reads CYL -1.50 D, it means a lens with -1.50 diopters is required to correct the astigmatism.
- Range of Values: Typically, CYL values range from -6.00 D to +6.00 D, but this can vary among individuals.
Direction of Astigmatism: Axis
- Axis: Axis is another important parameter closely related to CYL. It represents the specific orientation of astigmatism on the eye, measured in degrees (usually between 1 and 180 degrees).
- Combined Use: CYL values and the axis work together to ensure astigmatism is accurately corrected.
Importance
- Personalized Correction: Precise CYL values and axis are essential for the best visual outcome in astigmatism correction.
- Impact on Vision: Uncorrected or incorrectly corrected astigmatism can lead to blurred vision and eye strain.
In summary, Cylinder (CYL) and Axis in eyeglass prescriptions work together to correct astigmatism, providing a clear visual experience.
