Do you know what features astigmatism contact lenses have?Astigmatism lenses have different structures from those for myopia.
This section introduces the state of astigmatism in detail and explains the structure of astigmatism contacts.
What is astigmatism?
Astigmatism refers to the absence of focus because the refractive force varies from point to point.In normal eyes, the light entering the eye is properly bent in the cornea and lens and focused on the retina.
When you focus on the retina, you can see things most clearly.Astigmatism refers to a condition in which the cornea and lens, which act as lenses, are distorted and the retina is out of focus.
There are two types of astigmatism: regular astigmatism caused by the distortion of the lens in a certain direction, and irregular astigmatism caused by the protruding or uneven cornea.Regular astigmatism can be corrected with glasses and soft contact lenses, but in case of abnormal astigmatism, only hard contact lenses can be corrected.
There are three types of regular astigmatism: direct astigmatism (corneal and crystalline bodies are distorted up and down), inverted astigmatism (corneal and crystalline bodies are distorted horizontally), and oblique astigmatism (corneal and crystalline bodies are distorted obliquely).
Contact lenses and contact lenses for astigmatism are designed to bend differently depending on the direction.With ordinary contact lenses, the contact lens rotates due to blinking.However, astigmatism contact lenses are designed to inhibit rotation on the cornea as follows.
double slab off design
The upper and lower directions are thin and the left and right directions are thick.To prevent the lens from rotating, the upper and lower eyelids can be inserted.
prism ballast design
By thickening the lower part of the lens, it acts like a weight.The thickness of the contact lens is weighted positively and the pressure on the upper eyelid is used to correct the direction of the contact lens every time it blinks to prevent rotation.Both designs come in one-day to long-term use, but you can choose after consulting an ophthalmologist.