wie man Pluslinsen (Lesebrillen) als Training benutzt
Verfasst: 22.04.2007 08:35Ich habe hier mal einen Text aus meinen Dateien:
To select lenses for the Myopter or reading glasses (close-up lenses) you must know your distance refraction, the information on the prescription for your distance glasses (not contact lenses). Sometimes only a spherical correction is given. Other times, both a spherical and an astigmatic correction are given. On occasion, there may be only an astigmatic correction. The general rule is to select close-up lenses that are 3 diopters more positive (or less negative) than your distance prescription. This brings the far point in to 1/3 meter, or about 13 inches, which is a typical reading distance. Anything beyond that point is blurred. This is called reading at the far point. It is when the book is held at this distance and then pushed just a little further away, so that the print is slightly blurred, that the maximum relaxing effect on the ciliary muscles of the eyes is achieved.
Small amounts of astigmatism are usually ignored, allowing the use of spherical lenses without a cylindrical correction. Astigmatism can be thought of as a refractive error that only affects half of the cornea or lens, so that is no longer spherical. To account for the astigmatism, convert it to the spherical equivalent by cutting the amount in half. Thus, if the prescription shows -2.00 D with an additional -1.00 D in astigmatism, this could be converted to -2.50 D as the spherical equivalent. The close-up lenses would thus be +0.50 D. Quarter diopter steps such as 0.25 or 0.75 are moved to the closest half diopter value, usually in the positive direction. Each eye is calculated separately. Here are some examples of distance prescriptions with the usual close-up lenses shown in parentheses.
-6.00 (-3.00)
-5.00 (-2.00)
-4.50 (-1.5)
-4.75 (-1.5)
-4.00 x -1.00 at 90 degrees (-1.5). The spherical equivalent is -4.50.
-3.00 (zero or plano)
-2.00 x -.50 at 100 degrees (+1.00). The spherical equivalent is -2.25.
-1.00 (+2.00)
Emmetropia or normal 20/20 vision (+3.00)
The "x" on a prescription means "coupled with". That means that the spherical component and the astigmatic component which follows it are ground on the same lens. Usually, perhaps 90% of the time, the cylindrical correction is written in minus form as we have shown above. It can also be written in plus form, and some people, usually older ophthalmologists, still do this. The plus form can be easily transposed into the minus form, which is the preferred way. Ask your eye doctor to provide your prescription in minus form.
Note that the above rules do not pertain to a child who is hyperopic (farsighted). A child who is +2 or +3, for example, does not normally need reading glasses unless prolonged close work causes that hyperopia to diminish to zero. Therefore you should ask the eye doctor to tell you what the actual refraction is, either plus or minus.
The rules for selecting close-up lenses are provided here for the use of anyone, eye doctors and non-doctors. If you need assistance in understanding these rules, contact us by email.
Quelle
Man wählt die Stärke so, dass man -3 Dioptrien kurzsichtig ist. Heisst, man kann bis 33cm scharf sehen. Etwas weiter weg wird es dann unscharf. Also der Bereich, in dem man ja trainieren möchte.
Und wer nun eh schon -6 Dioptrien in der Brille hat, nimmt dann für nähere Arbeit (um die 40cm weit weg) eine Brille mit 3 Dioptrien weniger, damit er dann auf die -3 Dioptrien kommt.
Und wer weniger als -3 Dioptrien in der Brille hat, ergänzt die fehlenden Dioptrien dann mit einer Plusbrille (die ja kurzsichtig macht), bis er auf die -3 Dioptrien kommt.
lieben Gruß
Nicole
To select lenses for the Myopter or reading glasses (close-up lenses) you must know your distance refraction, the information on the prescription for your distance glasses (not contact lenses). Sometimes only a spherical correction is given. Other times, both a spherical and an astigmatic correction are given. On occasion, there may be only an astigmatic correction. The general rule is to select close-up lenses that are 3 diopters more positive (or less negative) than your distance prescription. This brings the far point in to 1/3 meter, or about 13 inches, which is a typical reading distance. Anything beyond that point is blurred. This is called reading at the far point. It is when the book is held at this distance and then pushed just a little further away, so that the print is slightly blurred, that the maximum relaxing effect on the ciliary muscles of the eyes is achieved.
Small amounts of astigmatism are usually ignored, allowing the use of spherical lenses without a cylindrical correction. Astigmatism can be thought of as a refractive error that only affects half of the cornea or lens, so that is no longer spherical. To account for the astigmatism, convert it to the spherical equivalent by cutting the amount in half. Thus, if the prescription shows -2.00 D with an additional -1.00 D in astigmatism, this could be converted to -2.50 D as the spherical equivalent. The close-up lenses would thus be +0.50 D. Quarter diopter steps such as 0.25 or 0.75 are moved to the closest half diopter value, usually in the positive direction. Each eye is calculated separately. Here are some examples of distance prescriptions with the usual close-up lenses shown in parentheses.
-6.00 (-3.00)
-5.00 (-2.00)
-4.50 (-1.5)
-4.75 (-1.5)
-4.00 x -1.00 at 90 degrees (-1.5). The spherical equivalent is -4.50.
-3.00 (zero or plano)
-2.00 x -.50 at 100 degrees (+1.00). The spherical equivalent is -2.25.
-1.00 (+2.00)
Emmetropia or normal 20/20 vision (+3.00)
The "x" on a prescription means "coupled with". That means that the spherical component and the astigmatic component which follows it are ground on the same lens. Usually, perhaps 90% of the time, the cylindrical correction is written in minus form as we have shown above. It can also be written in plus form, and some people, usually older ophthalmologists, still do this. The plus form can be easily transposed into the minus form, which is the preferred way. Ask your eye doctor to provide your prescription in minus form.
Note that the above rules do not pertain to a child who is hyperopic (farsighted). A child who is +2 or +3, for example, does not normally need reading glasses unless prolonged close work causes that hyperopia to diminish to zero. Therefore you should ask the eye doctor to tell you what the actual refraction is, either plus or minus.
The rules for selecting close-up lenses are provided here for the use of anyone, eye doctors and non-doctors. If you need assistance in understanding these rules, contact us by email.
Quelle
Man wählt die Stärke so, dass man -3 Dioptrien kurzsichtig ist. Heisst, man kann bis 33cm scharf sehen. Etwas weiter weg wird es dann unscharf. Also der Bereich, in dem man ja trainieren möchte.
Und wer nun eh schon -6 Dioptrien in der Brille hat, nimmt dann für nähere Arbeit (um die 40cm weit weg) eine Brille mit 3 Dioptrien weniger, damit er dann auf die -3 Dioptrien kommt.
Und wer weniger als -3 Dioptrien in der Brille hat, ergänzt die fehlenden Dioptrien dann mit einer Plusbrille (die ja kurzsichtig macht), bis er auf die -3 Dioptrien kommt.
lieben Gruß
Nicole
)