Farsightedness – this is a visual impairment in which the image of surrounding objects is focused behind the retina, and not on its surface, as in a healthy eye. As a result, a person loses the ability to clearly see objects located in the immediate vicinity of the face, and tries to move away to see them. The disease is also characterized by rapid fatigue and redness of the eyes, a burning sensation in them, and headaches.
In medicine, farsightedness is called hypermetropia. This term comes from three Greek words: hyper (over), metron (measure) and ops (eyes). The prevalence of pathology among the adult population is extremely high – up to 35% of boys and girls by the time they reach adulthood have one or another degree of hypermetropia. And after 40 years, this disorder is diagnosed in more than 50% of people. You need to understand that children’s farsightedness is physiological in nature and occurs in 90% of three-year-old babies. However, not everyone’s visual apparatus acquires healthy functionality as they grow older, and in old age the body’s resources are depleted, and the problem of farsightedness becomes even more acute.
Any medical encyclopedia will tell you that hypermetropia is characterized by insufficient refraction and requires a constant strain of accommodation. Understanding these scientific definitions is not easy, so most people would like to know what farsightedness is in simple terms. Today we will try to tell you all the most interesting things about this disease in an accessible language: causes and symptoms, differences from myopia and other visual impairments, modern methods of correction and treatment. Here you will find answers to many important questions: how to avoid age-related farsightedness and what to do in order to detect the disease in time and slow down its development.
What is farsightedness in simple words?
Hypermetropia – this is a feature of the refraction of the eye, which lies in the fact that at rest, images of objects are focused in a plane located behind the retina, and not on it. While a person is young, and his farsightedness is not too pronounced, the visual apparatus can compensate for this defect with the help of accommodation tension. But with age, the eyes wear out and this ability is lost. Now let’s understand these concepts in detail, in simple words.
Refraction is the process of refraction of light rays passing through the optical system of the eye. When the rays are focused on the retina, its cells convert the received information into nerve impulses. Those, in turn, enter the brain, where the image appears. But if the focus is beyond the surface of the retina, as in hypermetropia, nearby objects are not seen clearly.
Refraction is measured in diopters and depends on several factors:
Distances between the cornea and the lens, and then between the lens and the retina;
The radius of curvature of the anterior and posterior surfaces of the cornea and lens.
The most important criterion for assessing the quality of vision in a person is the clinical refraction of the eye, that is, the position of the point of intersection of light rays relative to the retina in a state of rest of the visual apparatus. If the focus is located exactly on the surface of the retina, one speaks of 100% vision. If it shifts closer or further, there are corresponding violations: myopia and hyperopia.
Accommodation (from the Latin word for adaptation) is the mechanism we use to deal with this problem. With the help of tension and weakening of the ciliary muscle and the ligament of zinn, the refractive power of the lens changes, and our optical system adjusts to the visual perception of objects located at different distances: too close for us or too far away. The person seems to be twisting the lens of the binoculars, trying to “sharpen”. In this way, you can correct refraction within as much as five diopters! But the accommodation of tension is a non-eternal function, it is lost with age.
With congenital farsightedness, a person constantly needs to increase refraction. Because of this, the eyes quickly get tired, especially when reading, working at a computer and carefully studying small nearby objects. There is redness and burning of the conjunctiva, and with increased use of the visual apparatus, headaches develop. Hyperopia also acts as a fertile field for inflammatory and degenerative-dystrophic eye pathologies: keratitis, blepharitis, cataracts, glaucoma.
This statement is partly true, but only for older people who do not have a congenital visual defect and simply suffer from presbyopia (“senile eye”). Their lens is in a relaxed state, and at the same time, objects located in the distance do look quite clear. But if we talk about people who have farsightedness all their lives and are forced to strain their eyes for a long time, then by adulthood they see poorly both near and far.