What are the eye diseases and their symptoms

The eyes are not immune to illness. They may be troubled by a variety of diseases, but people do not properly discover them in their lives. There are many kinds of eye diseases. First of all, all aspects of the eyes, including myopia and hyperopia, refractive errors and astigmatism, retinal damage, and even the risk of blindness, will affect normal vision once they occur.

What diseases can harm eye health?

Astigmatism: Myopia and hyperopia are both spherical refractive errors, and its refractive system is spherically symmetrical. This spherically symmetrical refractive anomaly has the same refractive power on different meridian planes of the corneal interface.

The eyes are the windows to the soul. A pair of young and beautiful eyes is everyone's dream. However, the eyes are exposed to the external environment for a long time and are the most susceptible to aging. What are the main eye diseases?

What are the main eye diseases?

Myopia and hyperopia: To form a clear image of an object (focus), the eye must bend the light reflected from the object so that it falls directly on the retina. People with myopia can only see objects that are close to them clearly; objects that are far away appear blurry because the image is focused in front of the retina. The correction method is to let the myopic person wear concave lenses, which can move the focused light slightly backwards and fall exactly on the retina. The cause of hyperopia is the shortening of the anterior-posterior diameter of the eyeball. Light from nearby objects is focused behind the retina, making them appear blurry, and only distant objects appear clear. People with hyperopia can wear convex lenses to bend light slightly inward, helping it fall on the retina.

Astigmatism: Myopia and hyperopia are both spherical refractive errors, and its refractive system is spherically symmetrical. This spherically symmetrical refractive anomaly has the same refractive power on different meridian planes of the corneal interface.

Astigmatism is different, it is a non-spherically symmetrical refractive system. Astigmatism has different refractive powers in different meridian planes of the cornea. Because the corneal curvature of an astigmatic eye is asymmetric, the light from a point light source cannot form a clear point image on the retina after being refracted by the eye. Light rays reaching different meridian planes of the cornea cannot be focused at the same time in the eye, so it is called astigmatism. The result is distortion of the image or unclear vision.

Astigmatism is divided into regular astigmatism and irregular astigmatism. The astigmatism usually refers to regular astigmatism. Regular astigmatism is usually divided into the following five types: (1) unipolar hyperopic astigmatism: one principal meridian is hyperopic and the other principal meridian is emmetropia; (2) unipolar myopic astigmatism: one principal meridian is myopic and the other principal meridian is emmetropia; (3) compound hyperopic astigmatism: both principal meridians are hyperopic but with different refractive powers; (4) compound myopic astigmatism: both principal meridians are myopic but with different refractive powers; (5) mixed astigmatism: one principal meridian is hyperopic and the other principal meridian is myopic.

The method of correcting astigmatism varies depending on the type of astigmatism. For simple hyperopic astigmatism, a convex cylindrical lens with appropriate degree and a certain axis should be worn; for simple myopic astigmatism, a concave cylindrical lens with appropriate degree and a certain axis should be worn; for compound astigmatism, a convex-convex (or concave-concave) composite cylindrical lens with appropriate degree and axis should be worn; for mixed astigmatism, a convex-concave composite cylindrical lens with appropriate degree and axis should be worn. But no matter which type of astigmatism it is, the glasses should strictly measure the axis of the cylindrical lens so that the astigmatism can be effectively corrected in the meridian plane that needs to be corrected.

The main eye diseases include irregular astigmatism. Since the refractive power is different on the same meridian plane, cylindrical lenses are not effective in correction. Contact lenses can be tried for correction.