Nearsightedness (myopia) is a condition that prevents a human eye from clearly seeing the objects located at far distances. The myopic eye does not focus the image on the specific area of the retina, but focuses it in front of the retina instead. As a result, the image appears blurred due to a discrepancy between the strength of the eye’s optical system and the length of the eye. As a rule, the myopic eye has an eyeball increased in size (axial myopia), although this eye problem can also occur due to excessive strength of its refracting apparatus (index myopia). The bigger this discrepancy is, the higher myopia appears.
Degrees of myopia
Ophthalmologists distinguish several types of myopia:
- low (up to 3.0D),
- medium (from 3.25 up to 6.0D),
- high (more than 6D). High myopia can reach considerable numbers: 15, 20, 30D and more.
Myopic people need glasses to see clearly at a far distance and in many cases even at a closer distance (when myopia exceeds 6-8 diopters or more). Unfortunately, glasses do not always successfully correct a person’s vision, which deals with either dystrophic or other types of changes in the layers of a myopic eye.
Myopia can be congenital or can develop in course of time. Sometimes it can increase or progress. A myopic person can see even small details at a close distance, but the farther the object is located, the less clearly a person can see it. Any myopia correction aims at weakening the strength of a refracting apparatus in such a way that would allow an image to be focused on the specific area of the retina (i.e. to come “back to normal”).
Usually myopia is accompanied by the eye ball enlargement causing retina stretching. The higher myopia degree the higher is the risk of retinal problems.