Unit 9 HBiol, Eye Information
50
A 20/50 vision rating means the person has move up to 20 feet to discern details that a person with normal vision can see from ____________ feet away. - Vision is worse than average
Aqueous humor
Name of the fluid that is continually secreted by ciliary processes, flows through anterior cavity and is drained by the scleral venous sinus (Canal of Schlemm). It helps maintain eye shape and nourishes the avascular lens and cornea.
Lacrimal gland
Name of the gland that secretes fluid (tears) that empty onto the surface of the conjunctiva.
Choroid
Name of the heavily pigmented layer that prevents light scattering within the eye
Vitreous humor
Name of the jelly-like substance that helps reinforce the eyeball - help maintain the shape and prevent the eyeball from collapsing, and holds the retina flush against the internal portions of the eyeball
Vascular tunic
Name of the layer of the eye that consists of three Parts: Choroid, ciliary body, and iris
Zonular fibers
Name of the string-like structures that hold the lens in place. Also called the suspensory ligaments.
Suspensory ligaments
Name of the string-like structures that hold the lens in place. Also called the zonular fibers.
Optic disk
Name or the region where the axons of neurons exit the eyeball as the optic nerve. Area contains no rods or cones; thus we cannot see an image that strikes this region and hence is your bind spot.
Ciliary muscle
Name the muscular structure that attaches to the lens by means of radially arranged fibers called the zonular fibers or suspensory ligaments.
Choroid
Name the nutritive layer of the eye that is highly vascular with dark pigment produced by melanocytes. Blood vessels provide oxygen and nourishment to the retina and the black pigment functions to absorb stray light rays.
Iris
Name the pigmented "diaphragm" of the eye that controls the size of the pupil
Ciliary body
Name the structure that consists of the ciliary muscle and ciliary processes.
Ciliary body
Name the structure that contains ciliary muscle that controls the shape of the lens
Lens
Name the structure that lies posterior to the iris and pupil and helps focus images on the retina for clear vision.
Accommodation
Term for the ability the ability of the eye to change its focus by changing the shape of the lens from distant to near objects or vice versa within 20 feet
Refraction
Term for the bending of light
Hyperopia
Term for the inability to focus well on close objects; farsightedness
Night blindness
Term or the inability to see well in the dark; often a result of vitamin A deficiency
Sclera
The "white" of the eye is called the _______________
15
A 20/15 vision rating means the a person at 20 feet is able to see details that would require someone with normal vision to move up to ________ feet to see. Vision is better than average
Pupil
A hole; appears black, allows light to enter the eye
Meibomian gland
A lipid-rich product that helps to keep the eyelids from sticking together is produced by the _________
Cateracts
A man in is early 60's comes into the clinic complaining of fuzzy vision. An eye examination reveals clouding of his lenses. What is likely the problem?
Fovea centralis
Area of acute or discriminatory vision - It is the focal point and contains only cones
Fovea centralis
Area of highest visual acuity or sharpest vision - your focal point. Hint: it is the structure that is a a small depression within the macula lutea and contains the densest concentration of cones.
Optic disk
Area of the retina that lacks photoreceptors
Iris
Colored part of the eye; regulates whether pupil is constricted or dilated, that is, the amount of light that enters the eye
Nearsighted
Common term for the condition where the Image is focused in front of the retina. Can see close objects but distant objects not seen clearly.
Farsighted
Common term for the condition where the image is focused behind the retina. Can see distant objects but close objects are not seen clearly.
Glaucoma
Condition of increasing pressure inside the eye, resulting from blocked drainage of aqueous humor
Strabismus
Condition that is a misalignment of the visual axes and loss of binocular vision; afflicts 5% of the population. Can be due to an underacting or overacting eye muscle, abnormal innervation, physical trauma, or a central processing problem
Cataract
Condition where there is clouding of the lens, resulting in loss of sight
Cataract
Condition where there is loss of transparency of the lens
Cones
Contain about 6 million of these photoreceptors in each eye; most concentrated in the central fovea of the macula lutea
Ptosis
Drooping of an eyelid
Macular degeneration
Eye condition where there is irreversible deterioration of the point of sharpest vision in the retina; much more common in elderly
Conjunctivitis
Inflammation of the conjunctival membrane due to pathogenic infection, allergy, or by physical/ chemical irritation can result in this condition. Hint, scientific name for pinkeye
Retina
Layer of the eye that contains the rods and cones
Scleral venous sinus
Located at the junction of the iris and cornea; drains aqueous humor. Also called the canal of Schlemm
Canal of Schlemm
Located at the junction of the iris and cornea; drains aqueous humor. Also called the scleral venous sinus.
Pterygium
Name of the condition where their is a benign thickening of the conjunctiva that grows onto the cornea. Eventually is may cause vision disruption by interfering with the normal smooth surface of the cornea. Most commonly caused by sun exposure.
Aqueous humor
Name of the fluid in the anterior cavity that provides nutrients to the lens and cornea
Rods
Over 120 million of these photoreceptors in each eye; located mainly in the peripheral regions of each eye.
Cones
Photoreceptors that are specialized for color vision and sharpness of vision
Rods
Photoreceptors used for black and white or night vision or low light vision. Not for color
Sty
Results from an infection of sebaceous glands at the base of eyelash hair follicles
Conjunctivitis
Scientific term for pinkeye
Scleral venous sinus
Structure that drains the aqueous humor of the eye. Also called the canal of Schlemm.
Zonular fibers
Structures that attaches the lens to the ciliary body. Also called the suspensory ligaments.
Eyelids
Structures that protect the eyes from excessive light and foreign objects, shades the eyes during sleep, and spreads lubricating secretions over the eyeball
Nasolacrimal duct
Tears drain into 2 small openings on the eyelids that flow through the superior and inferior lacrimal ducts that drain into the __________________________ which drains tears into the nasal cavity to help moisten the mucous membrane.
Astigmatism
Term for blurred vision, resulting from irregular curvatures of the lens or cornea
Myopia
Term for nearsightedness
Emmetropia
Term for normal vision
Trachoma
The greatest single cause of blindness in the world; caused by bacterial infection
Crystallins
The lens consists of transparent elastic proteins called _______________, arranged like the layers of an onion.
Conjunctiva
The protective mucous membrane that covers the sclera but not the cornea and the inside of eyelid
Nervous Tunic
The retina is part of what layer of the eye?
Fibrous Tunic
The sclera and cornea make up what layer of the eye?
Presbyopia
This term means old eye or vision. It is an inability of the eye to focus sharply on nearby objects due to loss of lens elasticity with age. Starts at about age 40
Cornea
Transparent, avascular structure that forms the anterior surface of the eyeball. It is the most anterior part of the eye and its curved convex surface assists the lens in focusing light.
Ciliary muscle
When looking at close objects the ____________________________ contracts which releases tension on the suspensory ligaments (zonular fibers) and thus the lens. The lens becomes more rounded, allowing the eye to focus on nearby objects. Label B in the diagram.
Ciliary muscle
When looking at far away objects the ____________________________ relaxes which increases tension on the suspensory ligaments (zonular fibers) and thus the lens. The lens becomes flatter, allowing he eye to focus on distant objects.