Question

A patient's far point is 135 cm and her near point is 15.0 cm.

In what follows, we assume that we can model the eye as a simple camera, with a single thin lens forming a real image upon the retina. We also assume that the patient's eyes are identical, with each retina lying 1.95 cm from the eye's "thin lens."

(a)

What is the power, *P*, of the eye when focused upon the
far point? (Enter your answer in diopters.)

diopters

(b)

What is the power, *P*, of the eye when focused upon the
near point? (Enter your answer in diopters.)

diopters

(c)

What power (in diopters) must a contact lens have in order to correct the patient's nearsightedness? (Assume that the object distance is infinite.)

diopters

(d)

Is this contact lens a converging or diverging lens?

converging diverging

Answer #1

(a) Where is the near point of an eye for which a contact lens
with a power of +2.95 diopters is prescribed?
cm (in front of the eye)
(b) Where is the far point of an eye for which a contact lens with
a power of -1.35 diopters is prescribed for distant vision?
cm (in front of the eye)

The near point of a patient's eye is 54.2 cm.
(a) What should be the refractive power ℛ of a
corrective lens prescribed to enable the patient to clearly see an
object at 23.0 cm?
ℛ = dpt
(b) When using the new corrective glasses, the patient can see an
object clearly at 26.8 cm but not at 23.0 cm. By how many diopters
did the lens grinder miss the prescription?
? = dpt

A. Where is the near point of an eye for which a contact lens
with a power of +2.85 diopters is prescribed? B. Where is the far
point of an eye for which a contact lens with a power of –1.10
diopters is prescribed for distant vision?

2. Correcting vision: quantitative. Corrective lenses work
because the lens bends light such that it, combined with the eye
itself, light forms a clear image on the retina. Another way to
think about this is that the corrective lens (glasses) form an
image of the object at a location where the eye can see clearly
without corrective lenses. For a nearsighted person viewing an
object very far away (object at infinity), the lens corrective lens
creates an image at the...

The uncorrected far point of Charlotte's eye is 2.1 m. What
refractive power contact lens enables her to clearly distinguish
objects at large distances? Assume that the distance from the
cornea-lens system to the retina is 2.0 cm and the normal near
point is 28 cm.

1) The distance from the lens to the retina is 3.1 cm, what is
the effective focal length of the lens when staring at an object
infinitely far away?
2) An object is moved to 40cm from the eye. What must the focal
length of the eye be to focus the image on the retina?
3) In the near sighted eye, images focus before hitting the
retina. Suppose the focal length of the lens is 1.9 cm, while the
distance...

The far point of an eye is 185 cm. A corrective lens is to be
used to allow this eye to focus clearly on objects a great distance
away. What should be the focal length of this lens?
What is the power of the needed corrective lens in diopters?

A near sighted person has a near point of 12 cm and a far point
of 40 cm. What power corrective lens is needed for her to have
clear distant vision? With this corrective lens in place, what is
her new near point?

A person is farsighted and has near point of 50 cm. Retina is at
a distance L = 1.7 cm. When wearing contact lenses and reading a
book 30 cm in front of the eye, what is the object distance for the
lenses? What is the desired image distance? Is the magnitude of the
image distance a minimum, maximum, or the only acceptable image
distance? Find the focal length and refractive power of the contact
lens that will fix this...

Contact lenses are placed right on the eyeball, so the distance
from the eye to an object (or image) is the same as the distance
from the lens to that object (or image). A certain person can see
distant objects well, but his near point is 50.0 cm from his eyes
instead of the usual 25.0 cm .
Part A
Is this person nearsighted or farsighted?
Is this person nearsighted or farsighted?
This person is nearsighted.
This person is farsighted....

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