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Physiological Optics Question--darn math.

Eyegirl2k7

Bridget Jones here
7+ Year Member
15+ Year Member
Nov 23, 2002
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Hi all,
I have an optics question from an assignment I'm doing. Rpames, if you're out there...you know what i'm talking about (Lecture 10-19 review).

The question is:
What is the depth of focus in diopters for an eye that perceives a clear retinal image for objects placed between 30-40 cm in front of the eye?

Since the clarity of image is between 30-40 cm, I converted that to diopters and said that the image is clear between -3.33 D and -2.50 D. Is it more complicated than that? Somehow i feel like it should b e.

Many thanks,
Eyegirl
:confused:
 

cpw

It's a boy !!!
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  1. Optometrist
unless i remember incorrectly i do believe that's all you have to do... but it has been two years.. somebody back me up here :)

good to see you again eyegirl ;)
 

Andrew_Doan

Doc, Author, Entrepreneur
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Oct 1, 2002
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  1. Attending Physician
Eyegirl2k7 said:
Hi all,
I have an optics question from an assignment I'm doing. Rpames, if you're out there...you know what i'm talking about (Lecture 10-19 review).

The question is:
What is the depth of focus in diopters for an eye that perceives a clear retinal image for objects placed between 30-40 cm in front of the eye?

Since the clarity of image is between 30-40 cm, I converted that to diopters and said that the image is clear between -3.33 D and -2.50 D. Is it more complicated than that? Somehow i feel like it should b e.

Many thanks,
Eyegirl
:confused:
You got it. The eye is able to focus the object between -3.33 D and -2.50 D.

If they had added in a refractive error, i.e. -5.00 or + 5.00, and the accomodation of the eye then you could calculate the near and far points of the eye. In this case, it appears to be an emmetropic eye focusing on an object at 30 cm = 3.33 D and 40 cm = 2.50 D.
 
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