Special Senses: Vision

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The iris is composed of two smooth muscle layers, one arranged radially and the other circularly. Which of these dilates the pupil?

The radial layer

Inability to focus well on close objects (farsightedness)

Hyperopia

What is conjunctivitis?

Inflammation of the conjunctiva

Explain why vision is lost in the optic disc

No photoreceptors

Ability to focus for close (less than 20 ft) vision

Accommodation

What is a sty?

An infection of the sebaceous gland of the eyelid

Fluid filling the anterior segment of the eye

Aqueous humor

Light-bending media of the eye

Aqueous humor, cornea, lens and vitreous humor

Blurred vision due to unequal curvatures of the lens or cornea

Astigmatism

In farsightedness the light is focused ______ the retina

Behind

Forms the bulk of the heavily pigmented vascular layer

Choroid

Modification of the choroid that controls the shape of the crystalline lens and contains the ciliary muscle

Ciliary body

Smooth muscle structures

Ciliary body and Iris

Form (by filtration) the aqueous humor

Ciliary processes of the ciliary body

The lens required to treat myopia is a _____ lens

Concave

Found in the fovea centralis, operate best in bright light and allow for color vision

Cones

During close vision, the ciliary muscle is ________, the suspensory ligament is ________, lens convexity is __________, and light refraction is ___________

Contracted, relaxed, increased and increased

Medial movement of the eyes during focusing on close objects

Convergence

Anterior continuation of the sclera - your "window on the world"

Cornea

Normal vision in the left eye visual field; absence of vision in the right eye visual field

Damage to the right optic nerve

Normal vision in both eyes for right half of the visual field; absence of vision in both eyes for the left half of the visual field

Damage to the right optic tract

Pupils dilate in what circumstances?

Dim light and when observing distant objects

The "near point" increases with age because the _______ of the lens decreases as we get older

Elasticity

Normal vision

Emmetropia

Area of critical focusing and discriminatory vision

Fovea centralis

Nearsightedness

Myopia

Part of the retina that lacks photoreceptors

Optic disc

Reduced ability to focus on near objects caused by loss of elasticity of the crystalline lens after age 45

Presbyopia

A convex lens, like that of the eye, produces an image that is upside down and reversed from left to right. Such an image is called a _____ image

Real

Light bending

Refraction

During distance vision, the ciliary muscle is _____, the suspensory ligament is _______, the convexity of the lens is _________, and light refraction is ___________

Relaxed, taut, decreased and decreased

Layer containing the rods and cones

Retina

How is the right optic tract anatomically different from the right optic nerve?

Right optic tract contains fibers from the lateral part of the right eye and the medial part of the left eye, right optic nerve only has fibers from the right eye

Dim light receptors, found in the periphery of the retina

Rods

Composed of tough, white, opaque, fibrous connective tissue

Sclera

The "white" of the eye

Sclera

Drains the aqueous humor from the eye

Scleral venous sinus

What is the function of the adipose tissue in the orbit of the eye?

Supports and surrounds the eyeball, protects and cushions

What modification of the choroid that is not present in humans is found in the cow eye? What is its function?

Tapetum Lucidum, reflects light that enters the eye, helps with night vision

Why does one have to blow one's nose after crying?

Tears drain into the nasal cavity through the nasolacrimal duct

The intrinsic eye muscles are controlled by what system?

The autonomic nervous system

Substance occupying the posterior segment of the eyeball

Vitreous humor

What does the retina look like? At what point is it attached to the posterior aspect of the eyeball?

White membrane, the optic disc


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