The difference between astigmatism and myopia

Astigmatism and myopia are eye problems that many young people may have nowadays. They both make it difficult for people to see things in the distance, but astigmatism not only makes it difficult to see clearly but also causes double vision when looking at things. Myopia is mainly caused by the posterior displacement of an individual's cornea, while astigmatism is caused by the curvature of the cornea. There are other differences between the two. Let's learn about them together today.

People with myopia see things blurry, and people with astigmatism will feel like double images. Because most people with astigmatism also have myopia (but there are also single astigmatism). Myopia refers to a state in which parallel light rays pass through the eye's refractive system and form a focus in front of the retina without using accommodation, and then appear as a scattered and blurred aperture on the retina. This refractive state is called myopia. Astigmatism refers to the situation where parallel light rays, after being refracted by the eye's refractive system, do not converge into a single point, but instead become many scattered light images. This is why it is called astigmatism and occurs in people of all ages.

Astigmatism, like myopia and hyperopia, is also a type of refractive error. Astigmatism generally does not change much (except for corneal injury and keratoconus). Astigmatism is divided into myopic astigmatism and hyperopic astigmatism. In layman's terms, light enters the eye and is refracted before it can form a clear image on the retina at the fundus. The refraction of light should be uniform, that is, the refraction force of each light ray should be equal. If the refractive power is unequal, some are large and some are small, the light cannot converge to one point, but is dispersed to multiple points, or two lines or two pieces, and it is impossible to form a clear image on the retina. This condition is called astigmatism.

There are many causes of astigmatism, but they can be summed up in two main ways: genetics and environment. Generally speaking, misalignment is irreversible. It is very good if we can control it and prevent it from developing. Lower degrees of astigmatism can be corrected with lenses.

Another type of astigmatism is called irregular astigmatism. The surface of the cornea is uneven and bumpy, which causes light scattering. In mild cases, the image is irregular, and in severe cases, no image can be formed. This astigmatism is often caused by corneal inflammation, scarring, or surgery. Irregular astigmatism cannot be corrected with lenses. An effective, simple and safe correction method is to wear glasses, but you must go to a qualified eyewear company or hospital to get your glasses fitted.

Symptoms of myopia: decreased vision

Myopia is characterized by a gradual decrease in distance vision, blurred distant objects, and normal near vision. However, high myopia is often caused by turbidity of the refractive medium and degeneration of the retina and choroid. Both distance and near vision are poor, and are sometimes accompanied by floating black shadows in front of the eyes. Visual fatigue

Myopic patients have good accommodation ability, but they need to overuse convergence power when working at close range, which destroys the balance and coordination between accommodation and convergence, leading to symptoms of muscular visual fatigue. The symptoms include eye swelling, eye pain, headache, double vision and blurred edges. Exotropia

Patients with moderate or severe myopia rarely or do not use accommodation when working at close range, which correspondingly weakens the radiation effect and can induce the eye to deviate outward, forming exotropia. Fundus changes

There is generally no change in the fundus of patients with mild myopia.