How many degrees of astigmatism do I need to wear glasses?

Many people do not understand astigmatism. In fact, if the degree of astigmatism is relatively high, you also need to wear glasses to correct it, because some glasses can correct low-degree astigmatism, but you must also pay attention to protecting your eyesight.

(1) Frame astigmatism correction should be the first choice. Especially for children and adolescents with astigmatism, their adaptability to wearing contact lenses is not yet mature. Astigmatism lenses contain cylindrical components. When binocular astigmatism is corrected, the cylinders of the two astigmatism lenses produce a binocular spatial vision effect. When the two column axes are in the oblique position, a spatial deformation effect of the object image will occur. The wearer will feel that the ground is tilted, objects are twisted and deformed, etc., and cannot accept the correction. Therefore, sufficient trial adjustments must be made before prescribing. In principle, the astigmatism should be appropriate and not overcorrected. In the case of small oblique angles, the cylindrical axes of both eyes should be adjusted to 90° or 180°. There is no need to stick to the axis difference of a few degrees in retinoscopy. For example, if the negative astigmatism axis of the right eye is 5° and that of the left eye is 175°, the adjustment axis can be 180° for both eyes, which may make the patient feel most comfortable. This is because under the condition of accurate cylindrical power, the new astigmatism produced by the oblique crossing of the cylinders at a small angle is already minimal and has little effect on vision; on the contrary, if the cylinder is in the correct axial position, the correction for one eye is perfect, but when using binocular vision, the spatial distortion synthesized by the cylinder can easily cause visual discomfort, so attention must be paid. Otherwise, it is easy to cause visual fatigue and even serious neuropsychiatric symptoms, which can easily affect the learning of children and adolescents.

(2) Contact lenses used to correct eye astigmatism refer to hard contact lenses: In recent years, reports of gas permeable rigid contact lenses (RGP) correcting eye astigmatism have become increasingly common. The principle of correction is to use the contact between the contact lens and the corneal surface, fill the corneal astigmatism on the corneal surface with tears, and there is no astigmatism on the lens surface, thereby achieving the effect of correcting eye astigmatism. This type of lens is very effective in correcting astigmatism, especially oblique astigmatism or high astigmatism. The spatial distortion problem of binocular vision can be significantly eliminated. For irregular astigmatism, wearing an RGP in one eye combined with frame glasses for both eyes can correct the unequal images in both eyes at the same time. It is reported that RGP correction can also inhibit the development of myopia in adolescents.

(3) Surgical treatment of astigmatism. Surgical treatment of astigmatism is mainly suitable for correcting high astigmatism, such as congenital corneal astigmatism, or surgical corneal astigmatism (most commonly from penetrating keratoplasty, but also from cataract extraction). For corneal astigmatism caused by surgery, the first thing to do is to make timely adjustments during the operation. The small scleral incision during cataract extraction can greatly reduce postoperative astigmatism. Intraoperative adjustments are particularly important for penetrating keratoplasty, which requires a 360° incision. A corneal astigmatism examination mirror can be used to adjust the incision sutures under a microscope, which has a good effect on reducing corneal astigmatism.