General Information About Refractive Errors
Refraction of Light Through the Eye Most refraction in the eye occurs when the light rays travel from the objects within your visual field to form a clear image inside the eyes. When the visual sys...
Myopia (Near-Sightedness)
More than 25% of people in the world have some degree of myopia (approximately 15 million of Iranians are nearsighted). Myopia is a medical term for nearsightedness. The most important cause of myop...
Hyperopia (Far-Sightedness)
The prevalence of hyperopia is less compared with myopia. The level of hyperopia is usually between +1 to +4 diopters, and it is rarely equal or greater than +8 diopters. Hyperopia occurs when eithe...
Presbyopia (Old Eyes)
A Prevalent Eye Condition in the Middle-Aged The image of a father or mother who holds a text farther away with stretched hands, squints, or moves glasses up and down is familiar to all of us. In ...
Astigmatism
Most people have some degree of astigmatism or ellipsoidal shape of the cornea, along with myopia. Astigmatism occurs when the cornea is shaped more like a cross section of a baseball, rather than...