What is axis in glasses?

Here's information about the axis in glasses, presented in Markdown format with linked keywords:

The axis in eyeglasses refers to the angle, measured in degrees from 1 to 180, that indicates the orientation of the <a href="https://www.wikiwhat.page/kavramlar/cylinder%20power">cylinder power</a> in a prescription meant to correct for <a href="https://www.wikiwhat.page/kavramlar/astigmatism">astigmatism</a>. It specifies the direction in which the cylindrical lens power should be placed to properly refract light and compensate for the uneven curvature of the cornea or lens of the eye.

• Range: The axis value always falls between 1 and 180 degrees.

• Importance: It is crucial for clear vision with astigmatism. An incorrect axis value can lead to blurry vision, headaches, and eye strain, even if the <a href="https://www.wikiwhat.page/kavramlar/sphere%20power">sphere power</a> and cylinder power are correct.

• Measurement: The axis is determined during an eye exam through a process called <a href="https://www.wikiwhat.page/kavramlar/refraction">refraction</a>, where the optometrist uses different lenses to find the combination that provides the sharpest vision.

• Notation: In a glasses prescription, the axis is typically listed after the cylinder power (CYL) value. For example, a prescription might read: Sphere: -1.00, CYL: -0.50, Axis: 90. This indicates that the cylindrical correction of -0.50 diopters should be oriented at an angle of 90 degrees.