Concept explainers
To determine:
The way through which the eye’s lens changes shape to allow focusing on distant objects.
Introduction:
Eyes help to see and view different objects by forming the image on the retina, a part of eye serves as a screen for the purpose of image formation. Accommodation in dark and light areas is a function of the eye. The eye is the sensitive part that provides vision. It consists of photoreceptor cells, such as rods and cone cells responsible for image formation in night and day.
To determine:
The defects that make focusing on a distant object impossible and name that condition.
Introduction:
Normal eyes focus at the cornea that has rounded contours helpful for bending the light rays. The lens plays an important role for final and sharp focusing. The encircling muscle adjusts the shape of the lens. Vision deficiencies occur due to the shape of the eyeball in the eyes.
To determine:
The type of lens used to correct it and also the ways through which the lens does so.
Introduction:
Both nearsighted (myopia) and farsighted (hypermetropia) conditions can be corrected with the help of lenses (with appropriate shaped lenses) and laser surgery (reshapes the cornea).
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Chapter 40 Solutions
Pearson eText Biology: Life on Earth with Physiology -- Instant Access (Pearson+)
- Explain the normal functioning of the eye to allow us to have visual acuity. What is meant by visual acuity? How does the eye adjust to facilitate this? Specifically, how do changes in near-point accommodation and astigmatism affect acuity? What is the problem with changes in near-point accommodation and astigmatism and why are they problematic? How can each of these be measured? Can these conditions be corrected? If so, how? Do these conditions change as we age?arrow_forwardA person with a myopic eye cannot see objects beyond 1.2 m distinctly. What should be the corrective lens used to restore proper vision?arrow_forwardIf your vision is normal and you put on your hyperopic friend’s glasses, is the focal point in front of your retina or behind it? (Hint: How does a lens that corrects hyperopia affect rays of light?)arrow_forward
- Distance between the eye and eye chart must be 6 meter during examination of visual acuity. Why?arrow_forwarddescribe the differences between normal, nearsighted, andfarsighted eyes and explain how defective focusing can becorrected by artificial lenses?arrow_forwardAlbinism is a condition in which melanin pigment is not made. How do you think vision is affected by albinism? When Mrs. Martinez visits her opthalmologist, she complains of pain in her right eye. the intraocular pressure is found to be abnormally elevated. What is the name of Mrs. Martinez's probable condition? What causes it? What might be the outcome if the problem is not corrected?arrow_forward
- Describe the structures of the human eye that light passes before reaching the retina. What are the functions of each of these structures?arrow_forwardUsing a line diagram, show how parallel rays of light are brought to a focus on the retina. Explain how this focus is maintained as the distance from the object to the eye is increasedor decreased (that is, explain accommodation).arrow_forwardWhat is the point of greatest visual acuity?arrow_forward
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