Farsightedness and nearsightedness – differences in the course and development of defects, symptoms and treatment

In the colloquial sense, a farsighted person is one who sees objects far away well, and badly those close by. Short-sighted vice versa: what is close to the eye is clear to him, but the farther away, the worse. Depending on the size of the defect, for a nearsighted person “close” will mean 2 meters or a few, a dozen, or a few tens of centimeters – the bigger the defect, the shorter the distance.

Colloquially speaking, it can be said that myopia “has it better”. His defect is easy to catch, diagnose and correct in time – or even make it stop and not worsen. In the case of farsighted people, the essence of the defect is more complicated, and the statement that “a farsighted person is one who sees objects far away well, and badly – those close by” is only part of the truth.

Farsighted people most often have trouble seeing objects clearly from any distance. Added to this are the problems of strabismus, involving a deficiency in accommodation (i.e., the adjustability of the eye; its ability to see objects at different distances), convergence (i.e., convergent eye movement coupled with accommodation; the simultaneous movement of the eyeballs toward the nose) and divergence (i.e., divergent eye movement; the movement to “straighten” the line of sight). Sometimes high hyperopia can even cause visual impairment.

For more information on farsightedness, see the article “Farsightedness – the most common questions.“.

Why does short-sightedness “have it better”?

Hyperopic people are often not even aware of their visual defect. If the so-called amplitude of accommodation (the accommodative capacity of the eye) is large enough, they see just fine on a daily basis! Children are considered to have accommodative capacity of up to 14 diopters, which makes diagnosing hyperopia much more difficult. Hardly: children up to the age of 3 have what is known as physiological hyperopia, which should subside as the eyeball grows (the eyes should undergo a process of emmetropization, i.e. get rid of hyperopia, to achieve a state without a visual defect).

It is estimated that about 90% of the youngest children are hyperacusis and the percentage decreases to 40-50% in 8.-10. year of age. If a school-age child does not signal vision problems, but intuition tells us that something is wrong with his vision, it is worth watching his activity: reluctance to read, squinting, one eye escaping, quickly giving up watching favorite movies because of eye fatigue may mean that the child is suffering from undiagnosed hyperopia.

Short-sighted already at the beginning of his “career” squints his eyes and pushes the book closer and closer. He moves from the last bench to the first bench or… sits in the last bench and gets A’s for shortcomings in his notebook, because he can’t see what is written on the blackboard. A visit to the ophthalmologist will probably show that the so-called school myopia has appeared – a small myopia that appears between the ages of 10 and 12 and can increase due to constant accommodative tension and with too much close visual work – when the child reads too much, studies, looks at the TV screen, smartphone or computer.

Since children, as already mentioned, have a high amplitude of accommodation, the refraction examiner must be very careful when prescribing glasses – there is a significant risk of overcorrection. To avoid errors, it is best to conduct the refraction test after the application of short-term cycloplegia (paralysis of accommodation).

NOTE: on the one hand, there is a risk of overcorrection, on the other hand, among some ophthalmologists, the view persists that with low myopia, it is better not to wear glasses so that “the eye does not get lazy and work.” Today, this view is considered anachronistic. The modern approach to myopia treatment recommends full correction of the visual defect. It has been proven that uncorrection or undercorrection (correction with too weak glasses) leads to faster progression of myopia.

To sum up: both overcorrection and undercorrection are detrimental to myopia. Hence the need to periodically check the progress of the visual defect. In teenagers, up to two-three per year is recommended.

Myopia correction methods

• Eyeglasses and soft contact lenses: short-sighted people need concave distracting or “minus” lenses. If he chooses soft contact lenses, it is worth knowing that they correct the defect much better at medium and high values – they do not disturb the field of vision (in glasses you can see well only straight ahead) and do not reduce the size of objects, so it is easier to drive in them, for example.
• Orthokeratology/orthocorrection: involves the correction of myopia with rigid high-gas-permeable lenses of inverted geometry, used overnight. During this time, the lenses cause a change in the shape (flattening) of the front surface of the cornea, so that during the day one can see sharply without glasses. The orthocorrection method can be used in myopia from 1D to 5D.
• Laser methods: in people with a stabilized defect, laser surgery can be undertaken. During myopia treatment ophthalmic laser flattens the central part of the cornea to reduce refractive power.

Far-sightedness correction methods

• Eyeglasses with convex lenses, or “plus lenses,” which are thicker in their central part than on the edge, and contact lenses.
• Laser methods: during treatment of farsightedness with an ophthalmic laser, a larger curvature is created, which increases the refractive power of the eye and thus improves comfort and visual acuity.