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.

Can the axis of your eye change?

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.

Is cyl and axis the same?

Axis. Axis describes the lens meridian that contains no cylinder power to correct astigmatism. If an eyeglass prescription includes cylinder power, it also needs to include an axis value, which follows the cylinder power. The axis is defined with a number from 1 to 180.

What is normal cyl and axis?

Those two values are cylinder and axis. While many individuals have somewhere between 0.5 and 0.75 diopters of astigmatism, the perfect eye with no astigmatism (ideal curvature of the cornea) will have 0 diopters. Individuals with 1.5 or more diopters will generally need contacts or eyeglasses for improved vision.

Does CYL and AXIS matter for contacts?

The cylinder value is required for the production of contact lenses for astigmatism. It is a negative value that corrects the corneal curvature. Axis is needed in astigmatism as a supplement to the cylinder.

Sphere, Astigmatism, Axis and The Eyeglasses Prescription

32 related questions found

What happens if you wear contacts with the wrong base curve?

If your lenses have the wrong diameter or base curve, you'll likely feel that something is always in your eye. If the lenses are too flat, your eyelids will tend to dislodge them when you blink. The wrong size lenses can even cause an abrasion of your cornea.

Is CYL the prescription for contacts?

Cylinder (CYL): If you require toric lenses to correct for astigmatism, your prescription will include values for Cylinder and Axis. The cylinder will always be a negative number that increases in measures of 0.25.

Is astigmatism 180 Axis bad?

An axis of 180 degrees, for example, means the astigmatism is horizontal. Therefore, this prescription means that the patient is moderately nearsighted, with a moderate degree of astigmatism in a horizontal direction.

What level of astigmatism needs correction?

People who have about 1.5 or more diopters of astigmatism usually opt to have corrective treatment such as glasses, contacts, or eye surgery.

What is a bad astigmatism number?

75 and 2 diopters is considered mild astigmatism. Between 2 and 4 diopters is moderate astigmatism, and 4 or more diopters is considered significant or “bad” astigmatism. Generally, eyes with 1.5 diopters of astigmatism or more require correction.

What do SPH CYL and axis mean?

This optician has elected to add "SPH," to confirm the right eye is being prescribed only spherical power. ... The cyl power has its axis at the 180 meridian, meaning the horizontal (180-degree) meridian of the eye has no added power for astigmatism and the vertical (90-degree) meridian gets the added -0.50 D.

Can you develop astigmatism?

Astigmatism may be present from birth, or it may develop after an eye injury, disease or surgery. Astigmatism isn't caused or made worse by reading in poor light, sitting too close to the television or squinting.

Is an astigmatism bad?

Astigmatism is not a disease nor does it mean that you have "bad eyes." It simply means that you have a variation or disturbance in the shape of your cornea.

How is astigmatism corrected?

Wearing corrective lenses is the simplest way to treat astigmatism by counteracting uneven curvatures of the cornea or lens. Corrective lenses may be worn as eyeglasses or contact lenses. Laser-assisted in situ keratomileusis (LASIK): The eye surgeon creates a thin flap in the cornea.

What is Cyl on eye prescription?

Cylinder (CYL) – This indicates the amount of lens power for astigmatism and represents the difference in the greatest and weakest powers of the eye, usually separated by 90 degrees.

Does Cyl matter for glasses?

Generally, the higher the CYL, the smaller the tolerance for the axis. Since the visual tolerances are small, that means that eyeglasses must be made very accurately to the prescription.

What axis is against the rule astigmatism?

In against-the-rule astigmatism, a plus cylinder is added in the horizontal axis (or a minus cylinder in the vertical axis). Axis is always recorded as an angle in degrees, between 0 and 180 degrees in a counter-clockwise direction.

What is a bad astigmatism reading?

Mild Astigmatism <1.00 diopters. Moderate Astigmatism 1.00 to 2.00 diopters. High Astigmatism 2.00 to 4.00 diopters. Extreme Astigmatism > 4.00 diopters.

What is Axis astigmatism?

Axis is measured in degrees, and refers to where on the cornea the astigmatism is located. Axis numbers go from 0 to 180. If you think of the eye as a map hanging on a wall, the 90 degree axis or line, runs up and down (or north to south) on the eye. The 180 degree line runs across the eye, east to west.

What is a normal axis for glasses?

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. The number may be between 1 to 180, where 90 represents the vertical position while 180 represents the horizontal position.

What does axis 90 mean on eye prescription?

The axis number on your prescription tells your optician in which direction they must position any cylindrical power in your lenses (required for people with astigmatism). This number shows the orientation or angle in degrees from 1 to 180. The number 90 means vertical position and 180 horizontal.

How do I know if my contacts are astigmatism?

Before your eye doctor can prescribe your contacts, they'll need to do a contact lens exam. If your corneal shape is a football rather than a sphere, they may recommend contacts for astigmatism.

Can I wear a different base curve?

Can I order contact lenses with a different base curve? You should never order contact lenses with a base curve that is different from your prescription. This can damage your eyes and cause problems with vision.

What if my PD is off by 2mm?

If the PD measured was 2mm off initially, by using a millimeter rule, the net cumulative error might be 4.5mm or more.

How do I know my base curve for contacts?

Base curve = 0.95 * 34.82 D = 33.07 D and then round up or down to the nearest whole diopter to arrive at the following final base curve to use for a contact lens over-refraction: Base curve = 33.00 D (actual measured base curve is 32.95 D)