Question

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

Answer #1

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...

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...

(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)

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?

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?

You
are designing eye glasses got someone whose neR point is 100 cm.
A) neglecting the eye lens distance, what focal length lens
should you prescribe so that an object can clearly be seen when
placed at 25 cm in front of the eye? (Hint =25 cm and q= -100
cm)
B) what is the lens power in diopters?

1. A person has refractive hypermetropia with a near
point at 3 m. They are to be prescribed a set of glasses that will
enable them to have normal close-in vision and the person’s glasses
will typically sit 2 cm in front of their eyes. (a) What is the
maximum optical power of this person’s eyes? (b) What is the
optical power of the glasses required?

Suppose that a person's lenses have a refractive power of 2.75 diopters that allow the person to focus on an object that is 25 cm from the eye. The glasses are 2.00 cm in front of the eyes.
a) Is the close point of this person greater than or less than 57.0 cm? What is the distance from the near point when the glasses have a refractive power of 2.53 diopters? Explain b) find the close point of this person.

What power of spectacle lens is needed to allow a farsighted
person, whose near point is 2.50 m, to see an object clearly that
is 20.0 cm away? Assume the spectacle (corrective) lens is held 2
cm away from the eye by eyeglass frames.

A farsighted eye is corrected by placing a converging lens in
front of the eye. The lens will create a virtual image that is
located at the near point (the closest an object can be and still
be in focus) of the viewer when the object is held at a comfortable
distance, usually taken to be 25.0 cm.25.0 cm. If a person has a
near point of 49.5 cm,49.5 cm, what power reading glasses should be
prescribed to treat this...

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