If you ever played with a person’s glasses – not that it is recommended, but we have all done it – all you saw was a blur when you looked through the lenses and you imagined that’s how they see without the glasses. So, what is the difference between nearsighted and farsighted people, if, in the end, both of them have blurry vision without their glasses?
Nearsighted people have difficulty in seeing at a distance. This is the most common refractive error existing and it is also known as myopia. Nearsightedness occurs when the eye ball is too long and the light rays focus on a point in front of the retina. This makes people squint to have a clearer image and it causes eye strain, headaches and eye fatigue. Doctors think that the condition is hereditary and that left uncorrected it can advance and the quality of the eyesight can deteriorate in time. Nearsightedness can be corrected with glasses and contact lenses or with laser surgery. The lenses used for correcting myopia are known as concave lenses and they have diopters (units in which the optical power of a lens or an optical mirror is measured) with minus numbers: -1, -2 etc. The further from the retina the image is formed, the bigger the lens’ curve has to be to correct the vision.
Farsighted people have difficulty in seeing up close. This is the condition known as hyperopia and it occurs when the eye ball is too short and the light rays focus at a point behind the retina. It usually affects people when they reach a certain age, normally over 40, although those who have had myopia may find that the condition levels out at some point. It can be corrected with glasses and contact lenses with plus diopters, or with surgery. The lenses used for correcting myopia are known as convex lenses and they have diopters (units in which the optical power of a lens or an optical mirror is measured) with plus numbers: +1, +2 etc. The further back in the retina the image is formed, the bigger the lens’ curve has to be to correct the vision.
Nearsighted people cannot see into the distance, while farsighted people cannot see up close. In both cases, what is seen is all a blur and the person affected feels the need to squint and to force the point of focus. Both conditions are corrected the same way and both can get worse if no action is taken at all.
Another difference between nearsightedness and farsightedness lies with the fact that farsightedness occurs mainly on account of old age, whereas nearsightedness can occur at any age. Both of them are hereditary, as are most eye conditions. Myopia is corrected by concave lenses which make the image form on the retina instead of in front of it, whereas hyperopia is corrected with convex lenses which make the image form on the retina instead of behind it.
|Cannot see at a distance||Cannot see up close|
|Is corrected with concave lenses, contact lenses and laser surgery||Is corrected with convex lenses, contact lenses and surgery|
|Is hereditary||Occurs naturally at a certain age|