What is astigmatism?
Astigmatism is a refractive error of the eye that is related to the curvature of the cornea. In some eyes, the cornea is curved at one angle and flattened at other angles. The reason for astigmatism is that these uneven thicknesses or curvatures of the cornea make the refractive index of the corneal meridians inconsistent, so that the light passing through these meridians does not gather at the same focal point and the light cannot be accurately focused on the retina to form a clear image, a condition called astigmatism.
How is astigmatism formed?
(1) Curvature astigmatism: caused by the uneven curvature of the refractive surface of the eye, often occurring in the cornea.
(2) Index astigmatism: mostly caused by changes in the refractive index of different areas of the lens, such as cataracts caused by changes in the refractive medium of the lens.
(3) astigmatism of optical decentring: such as the lens position is obviously oblique, trauma-induced lens hemianopia, etc.
What are the symptoms of astigmatism?
1. Blurred vision
Blurred vision is closely related to the degree and mode of astigmatism. People with mild astigmatism usually have normal vision, but may experience headaches, eyestrain and blurred vision when looking at objects at a certain distance. People with severe astigmatism have blurred and distorted vision. Seeing far and near is not very clear, and working at close range for a long time means that the eyes are swollen and headache reading scurry or have double vision.
2. Visual fatigue
The blurred image on the retina requires constant fine adjustment and distortion, so astigmatism, especially hyperopic astigmatism, is prone to visual fatigue. Young people with compound hyperopic astigmatism can often compensate with accommodation, which can result in pseudo simple hyperopic astigmatism, pseudo simple myopic astigmatism or pseudo compound myopic astigmatism depending on the degree of accommodation.
3. Abnormal head position
People with high asymmetric astigmatism in both eyes tend to adopt a tilted head position in order to see more clearly, which can be restored after astigmatism correction. People with high astigmatism often squint when looking at distant targets to achieve pinhole and slit effects to improve vision. People look through pinholes or slits to try to reduce the effect of astigmatism on their vision.
How is astigmatism treated?
Regular astigmatism – can be corrected with different cylindrical lenses according to the type of astigmatism and the degree of astigmatism.
Irregular astigmatism – can be corrected with rigid corneal contact lenses.
Surgery – high astigmatism in adults over 18 years old can be considered for keratoconus surgery
What are the consequences of pediatric astigmatism?
Astigmatism causes blurred vision and may lead to amblyopia and even strabismus. Therefore, the following are recommended.
(1). It is best to have the first full eye examination at the age of 3 to 4 years old, and regular eye examinations once or twice a year thereafter. Instruct young children to develop good hygiene habits and not to touch their eyes with their hands or other objects to avoid infectious eye diseases. Read books with adequate light and with a correct posture, and keep the distance between 30 cm and 40 cm.
(2). Choose reading materials in clear font, not too small.
(3). Watch TV at a distance of 5 to 7 times the diagonal of the TV screen. Do not read continuously for more than one hour. For those who need glasses, they should be examined by a physician before prescription.