The term “dioptres” inevitably stumbles upon anyone who has ever dealt with their visual acuity and possibly suffers from a diagnosed refractive error. Diopters describe the refractive power of lenses and indicate how much they can refract light in order to focus it correctly on your retina.<\/p>\n\n\n\n
The diopter value is not only important in diagnostics, but also has very practical effects on the treatment of refractive errors \u2013 be it the manufacture of a visual aid or the choice of an eye laser treatment.<\/p>\n\n\n\n
But what exactly are diopters? How do you calculate them, and what diopter value is normal? We will explore these and other questions in this article.<\/p>\n\n\n\n
A diopter (dpt for short) is a unit of measurement used to express the optical power of a lens or curved mirror. The diopter is defined as the reciprocal of the focal length in meters.<\/p>\n\n\n\n
D= 1f<\/p>\n\n\n\n
For example, if a lens has a focal length of one meter, its optical power is 1 diopter. A lens with a shorter focal length has more diopters because it can refract light more sharply and focus faster.<\/p>\n\n\n\n
This unit of measurement is also used in ophthalmology or optics \u2013 to indicate the refractive power of the eye or lens in the eyeball. It forms the basis for determining the vision of the human eye and, if necessary, determining what a treatment should look like. This can concern the strength of the lenses of reading glasses or progressive spectacles, but also a possible method for laser vision loss.<\/p>\n\n\n\n
The optimal diopter value for the eye is 0. This enables 100% sharp vision both at close range and at a distance.<\/p>\n\n\n\n
However, not every slight deviation from this theoretical ideal value is problematic: from a deviation of 0.5, treatment can be useful; with a significantly higher diopter value (usually above +\/- 1), however, one no longer speaks of a slight refractive error \u2013 this is where action should be taken.<\/p>\n\n\n\n
0 dpt \u2013 normal vision<\/p>\n\n\n\n
0 to +\/-1 dpt \u2013 slight refractive error<\/p>\n\n\n\n
+\/-1 to +\/-5 dpt \u2013 moderate refractive error<\/p>\n\n\n\n
+\/-5 dpt or higher \u2013 severe refractive error<\/p>\n\n\n\n
Dioptric values are determined by an eye test performed by an ophthalmologist or optician. A refractometer and various lens strengths are used to measure how much the lens has to refract the light in order to produce a sharp image on the retina.<\/p>\n\n\n\n
The test involves reading letters at different sizes and distances to determine the exact visual acuity. The diopter values determined indicate which correction by glasses, contact lenses or eye lasers is necessary to ensure optimal vision.<\/p>\n\n\n\n
When you visit an ophthalmologist or optician, they use an eye test to determine how many dioptres your eye needs to adjust your visual acuity to a normal-sighted eye. The numbers on your prescription or eyeglass passport represent the diopters needed to focus the light on your retina and allow you to see clearly with optimal vision.<\/p>\n\n\n\n
Good to know at higher diopter values: Here it may be that you have to assume a different value for the prescribed visual aid, depending on whether you use glasses or contact lenses.<\/p>\n\n\n\n
Of course, it is above all up to the optician to read your eyeglass prescription and to suggest an appropriate visual aid. Nevertheless, many people are interested in what values such as SPH, CYL or AXIS mean on your prescription \u2013 reason enough to explain them in a nutshell.<\/p>\n\n\n\n
The SPH value (spherical value) indicates the strength of the spherical correction necessary to correct your refractive error. It is measured in diopters (dpt). A negative SPH value indicates nearsightedness (myopia), while a positive SPH value indicates farsightedness (hyperopia). This value determines how much light must be refracted to produce a sharp image on the retina.<\/p>\n\n\n\n
The cylinder value (CYL) indicates the strength of the correction for astigmatism (corneal curvature). Astigmatism is caused by an uneven curvature of the cornea, which leads to blurred vision. The cycl value can be positive or negative and shows how much the lens has to refract the light in a certain direction to correct the distortion.<\/p>\n\n\n\n
The axis indicates the direction of astigmatism and is measured in degrees, on a scale from 0\u00b0 to 180\u00b0. This value indicates the angle at which the astigmatism must be corrected. The axis value is only relevant if a CYL value is also specified in the eyeglass prescription, as it determines the exact orientation of the cylinder correction.<\/p>\n\n\n\n
An eyeglass prescription may also include additional values such as the addition value (add), which indicates the strength of the near correction for varifocal spectacles or reading glasses. This value is particularly important for presbyopia.<\/p>\n\n\n\n
Most vision problems result from the eye’s inability to correctly focus light on the retina. This problem is usually due to the shape of the eye. Defective vision, the manifestation of which is indicated by this refractive power, are:<\/p>\n\n\n\n
While glasses and contact lenses are effective solutions, they are only temporary aids that need to be updated regularly. Laser eye treatment can provide a permanent solution by correcting the refractive error at its source \u2013 the cornea. This procedure adjusts the shape of the cornea to ensure that light is focused directly onto the retina, potentially completely eliminating the need for corrective lenses.<\/p>\n\n\n\n
Laser eye treatment can correct a number of diopters and allow many people with myopia, hyperopia and astigmatism to achieve very good visual performance. The following reasons speak in favour of laser eye treatment:<\/p>\n\n\n\n
Eye lasers can correct defective vision in a wide diopter range. In myopia, values up to -10 diopters can usually be treated, while hyperopia can be corrected up to +5 diopters. Astigmatism can be corrected up to about 6 dioptres.<\/p>\n\n\n\n
However, the exact limit depends on the individual corneal thickness and shape. Before laser treatment, a detailed preliminary examination is necessary to determine the suitability for the procedure and to ensure the best results.<\/p>\n\n\n\n
Lens replacement may also be considered as an alternative to laser eye surgery. Although this is not one of the classic laser eye procedures, it is also suitable for people with thin corneas or severe refractive errors.<\/p>\n\n\n\n
Various modern methods for correcting refractive errors are available at B\u00e1nyai Neue Augen. These procedures are specially tailored to different diopter values and visual impairments:<\/p>\n\n\n\n
SMILE\u00ae Pro<\/strong> \u2013 The SMILE\u00ae Pro procedure is a minimally invasive method that is particularly used for myopia and corneal curvature. It is suitable for myopia up to -10 diopters and astigmatism up to 5 diopters. This procedure does not require flap creation, which keeps the cornea stable and shortens the regeneration time. It is well suited for patients with thin corneas and reduces the risk of dry eyes after surgery\u200b\u200b.<\/p>\n\n\n\n