po film manufacturers to explain to you what is astigmatism invisibility

Does astigmatic invisibility need to be worn with a mark or with an automatic rotation? This lens is -0.75DS-2.00DC, the astigmatism is larger than the spherical lens, does it affect the wearing effect of astigmatism contact lenses?

Astigmatic contact lenses are worn on the cornea through blinking and eye movement, relying on the product's own special design to achieve axial stability.

Astigmatic contact lenses are designed for people who have astigmatic symptoms that cannot be corrected with regular contact lenses. If the customer has low astigmatism (less than 0.75D) and all corneal astigmatism, you can wear ordinary contact lenses and use the tear film lens formed between the contact lens and the cornea to correct astigmatism. Otherwise, use specialized astigmatic contact lenses.

The most important design principle of astigmatic contact lenses is the positioning of the lens, because only by maintaining axial stability of astigmatism can it correct astigmatism. There are three common lens positioning methods on the market:

(1) Prism vertical weight method. The prism of 1Δ ~ 1.5Δ is designed on the lens. Due to the relationship of gravity, the thick edge of the prism is always moved in the downward direction to maintain the stability of the lens.

(2) bilateral thinning method. The upper edge area of the lens is thinly treated, and the thin area interacts with the eyelid (especially the upper eyelid) to position the lens and keep the axial position in dynamic stability.

(3) Cutting edge method. Cut off a part of the lower part of the lens, the width is about 0.5 ~ 1.5mm, so that the missing part is fixed in the lower eyelid margin to prevent rotation.

No matter which method is used, the lens worn on the customer's cornea may have a certain deviation, then the prescription needs to be corrected, according to the principle of positive plus negative. After the customer wears the mirror, he observes through the slit lamp. If the observation is that the axial position is reversed by 10 degrees, the axial position of the original optometry is 180 degrees, and the axial position of the astigmatic contact lens should be set at 170 degrees. If the observation is 10 degrees clockwise, the axis of the original optometry is 180 degrees, and the axis of the astigmatic contact lens should be set at 10 degrees.