Which of following is a true statement regarding light and the human eye?
Possible Answers:Light will pass through the aqueous humor before passing through the vitreous humor
Light will pass through the lens before passing through the cornea
The retina is a small disc located at the focal point at the back of the eye
The pigments of the iris contain small numbers of photoreceptors
Correct answer:Light will pass through the aqueous humor before passing through the vitreous humor
Explanation :The first structure that light will encounter as it enters the eye is the cornea, a transparent protein disc designed to refract light toward the eye interior. The aqueous humor is the liquid medium between the cornea and the lens of the eye. Light will pass through the aqueous humor and the pupil before hitting the lens. The lens then focuses the light onto the back of the eye. The vitreous humor is the liquid medium between the lens and the retina at the back of the eye.
The iris is used to control the shape of the pupil, and does not contain photoreceptors. All photoreceptors are located on the retina, which lines the back wall of the eye. A small region known as the fovea centralis houses a large number of cones (photoreceptors) at the back of the eye, but is part of the greater retinal structure.
The only true statement given is that light will pass through the aqueous humor before passing through the vitreous humor.
Diana takes the subway to and from school every day. Her family’s apartment, situated in a low-income neighborhood of New York City, is a thirty-minute walk from the subway station. During her trips to the subway, Diana loves to watch people work, play, and socialize. She feels very safe in her community because she trusts the people around her.
Diana’s mother is having trouble seeing clearly. The lens of her eye appears white and cloudy. Which of the following most likely describes this situation?
Possible Answers: Correct answer: Explanation :The symptoms describe a “cataract.” Cataracts form when a protein coat builds up and cause a white barrier to form that limits vision. It is normally surgically removed. “Astigmatism” is a misshapen cornea that can also cause vision problems. “Conjunctivitis” is a disorder that is made evident by the inflammation of the sclera, or white part of the eye. Last, “glaucoma” describes damage caused to the optic nerve, usually by a buildup of excess fluid in the eye.
In myopia, which of the following abilities is impaired?
Possible Answers:Ability to focus on close objects
Ability to focus on distant objects
Ability to shift focus from distant objects to close objects
Ability to discern color
Correct answer:Ability to focus on distant objects
Explanation :Myopia, often called nearsightedness, is an inability to being distant objects into clear focus. This may be due either to excess curvature of the cornea or to length of the eyeball itself causing the focal point of light rays to fall in front of the retina, rather than against it.
Which of the following terms describes the inability to focus vision on close-up objects?
Possible Answers: Correct answer: Explanation :“Presbyopia” is the term for the inability to focus the vision on close-up objects. It is most commonly caused by loss of elasticity of the lens of the eye as individuals age.
On the other hand, the other choices are incorrect. “Amblyopia” is a general term used to denote cases in which one eye is communicating less visual information to the brain, resulting in a loss of vision in that eye In other words, the brain learns to ignore visual stimulation from the non-dominant eye. A common cause of amblyopia is “strabismus”—commonly known as “lazy eye.” It is defined as a lack of coordination between extraocular muscles that prevents the eyes from orienting in the same direction. In this case, there will almost always be a dominant eye, and if the condition is not corrected in childhood, the non-dominant eye generally suffers permanent vision loss. “Nystagmus” is a condition of involuntary eye movement (i.e. the eye seems to shudder, generally in a horizontal plane) that may or may not be associated with visual impairment. It can have numerous etiologies, including nervous system disorders, alcohol or drug reaction, congenital defect, or inner-ear disorder.
Which of the following structures of the eye is not responsible for the refraction and focusing of light?
Possible Answers: Correct answer: Explanation :Light is refracted and focused by the cornea, the anterior chamber, and the lens. The retina is a thin layer of nervous system tissue, which receives focused light patterns and transmits those patterns to the brain via photoreceptor cells.
Which of the following is not a primary function of the extrinsic eye muscles?
Possible Answers:Saccadic eye movements
Tracking moving objects
Dilation of the pupils
Correct answer:Dilation of the pupils
Explanation :The extrinsic muscles of the eye are primarily responsible for the mechanical movement of the eyeball. The main movements of the eye are convergence during accommodation, saccadic movements, tracking, and maintenance of a horizontal position. Dilation of the pupils is dependent on intrinsic muscles of the eye.
Which muscle is responsible for changing the shape of the lens during accommodation?
Possible Answers:Medial rectus muscle
Correct answer: Explanation :The structure responsible for changing the shape of the lens during accommodation is the ciliary muscle. This is a ring of smooth muscle in the middle layer of the eye that is attached to the lens via the suspensory ligament. Contraction and relaxation of the ciliary muscle will cause the suspensory ligament to tighten (in the case of relaxation of the ciliary muscle) or relax (in the case of contraction of the ciliary muscle). This affects the thickness of the lens, allowing for accommodation.
The sphincter pupillae and dilator pupillae are both responsible for changing the shape of the iris, rather than the lens, and the medial rectus muscle is an extrinsic eye muscle that moves the whole eye medially.
Which division of the nervous system controls the dilator pupillae and is known as the iris dilator muscle?
Possible Answers:The somatic division of the peripheral nervous system
The sympathetic division of the autonomic nervous system
The sensory division of the peripheral nervous system
The parasympathetic division of the autonomic nervous system
Correct answer:The sympathetic division of the autonomic nervous system
Explanation :Control of the muscles responsible for dilation of the pupil is mediated by the sympathetic division of the autonomic nervous system. During states of fear, sexual arousal, or heightened attention, the pupil will dilate due to the stimulation of the dilator pupillae, or iris dilator muscle.
Deficits in which cranial nerve could cause ptosis (i.e. the drooping of the upper eyelid)?
Possible Answers:CN VI (the abducens nerve)
CN VII (the facial nerve)
CN III (the oculomotor nerve)
CN IV (the trochlear nerve)
Correct answer:CN III (the oculomotor nerve)
Explanation :The levator palpebrae superioris is the muscle responsible for elevating the upper eyelid. It is innervated by CN III, the oculomotor nerve. CN IV (the trochlear nerve) and CN VI (the abducens nerve) are both responsible for innervation of various other muscles of eye movement, while the facial nerve (CN VII) is primarily responsible for control of the muscles of expression, for taste, and for motor innervation to the muscles of the inner ear.
Which of the following is the term for the process by which the eye's lens changes shape to bring close or distant objects into focus on the retina?
Possible Answers: Correct answer: Explanation :The lens of the eye must be able to change its shape in order to re-focus the vision on near or far objects as the eye moves. This process is called “accommodation.” On the other hand, “convergence” is the ability of the eyes to move toward one another in order to focus on objects that are very close up. “Mydriasis” is the term for dilation of the pupil, and "contrast" is a visible quality of difference in color or brightness of objects, and not a function of the eye itself.
← Previous 1 2 Next →
If you've found an issue with this question, please let us know. With the help of the community we can continue to improve our educational resources.
If you believe that content available by means of the Website (as defined in our Terms of Service) infringes one or more of your copyrights, please notify us by providing a written notice (“Infringement Notice”) containing the information described below to the designated agent listed below. If Varsity Tutors takes action in response to an Infringement Notice, it will make a good faith attempt to contact the party that made such content available by means of the most recent email address, if any, provided by such party to Varsity Tutors.
Your Infringement Notice may be forwarded to the party that made the content available or to third parties such as ChillingEffects.org.
Please be advised that you will be liable for damages (including costs and attorneys’ fees) if you materially misrepresent that a product or activity is infringing your copyrights. Thus, if you are not sure content located on or linked-to by the Website infringes your copyright, you should consider first contacting an attorney.
Please follow these steps to file a notice:
You must include the following:
A physical or electronic signature of the copyright owner or a person authorized to act on their behalf; An identification of the copyright claimed to have been infringed; A description of the nature and exact location of the content that you claim to infringe your copyright, in \ sufficient detail to permit Varsity Tutors to find and positively identify that content; for example we require a link to the specific question (not just the name of the question) that contains the content and a description of which specific portion of the question – an image, a link, the text, etc – your complaint refers to; Your name, address, telephone number and email address; and A statement by you: (a) that you believe in good faith that the use of the content that you claim to infringe your copyright is not authorized by law, or by the copyright owner or such owner’s agent; (b) that all of the information contained in your Infringement Notice is accurate, and (c) under penalty of perjury, that you are either the copyright owner or a person authorized to act on their behalf.
Send your complaint to our designated agent at:
Charles Cohn Varsity Tutors LLC
101 S. Hanley Rd, Suite 300
St. Louis, MO 63105
Or fill out the form below:
