Farsightedness (hypermetropia) is a visual impairment in which a person sees poorly near and fairly well far away. However, with a high degree of farsightedness, the patient may have trouble seeing distant objects.
Farsightedness traditionally occurs due to the fact that the eyeball has an irregular shape, it is, as it were, compressed along the longitudinal axis. As a result, the image of the object is focused not on the retina, but behind it. Often an irregular, compressed shape of the eyeball is combined with insufficient optical power of the cornea and lens. Much less often, farsightedness is due only to the weakness of the optical system of the eye with a normal length of the eyeball.
A farsighted person can hold text very close to their eyes because it enlarges the image of the text on the retina. However, the image does not get better, it just gets bigger. The patient often squints in an attempt to help accommodation, which can contribute to the development of blepharitis and conjunctivitis, along with constant tension of the ciliary muscle.
With prolonged work close to hypermetropes, complaints of fatigue, eye pain, headaches, lacrimation, burning in the eyes, tingling in the eyes may occur. There may be discomfort when looking at the light or intolerance to bright lighting. This is called accommodative asthenopia. Accommodative asthenopia is more pronounced, the greater the degree of hypermetropia.
Farsightedness can be of three degrees and is determined by the number of diopters that a hypermetropic eye lacks in order to become emmetropic:
- mild hypermetropia – up to 2.0 diopters;
- moderate hypermetropia – up to 4.0 diopters;
- hyperopia of a high degree – more than 4.0 diopters.
With low degree hypermetropia, the eye copes with its task with the help of accommodation. And with moderate and high hypermetropia, correction is required for both distance and close distances.
Unfortunately, there are currently no therapeutic methods for the treatment of farsightedness, as well as myopia. Farsightedness is corrected with glasses or contact lenses. Hypermetropia can be radically cured with the help of a surgical operation. Surgical methods for correcting hypermetropia are aimed at increasing the optical power of the eye in order to force the light rays to focus on the retina. Currently, the most common surgical procedures for the treatment of farsightedness are laser thermokeratoplasty (LTK), clear lens replacement, LASIK, positive lens implantation, and thermokeratocoagulation (TKK).