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25 Cards in this Set
- Front
- Back
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Outer Layer of the eye
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Sclera
Cornea |
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Sclera (normal)
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Dense, white, opaque outer layer that is continuous with the cornea (whites of the eyes)
Tough fibrous protective tissue Prevents scattered light from entering the eye Protects the eye |
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Cornea (normal)
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Primary function is to refract light onto the facial point on the retina
Highly transparent avascular protective membrane that allows light to pass through the retina Light is bent and refracted to properly focus on the receptors in the back of the eye High water content NOTE: more transparent, the clearer vision will be. No blood supply to it. Heals very quickly. |
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Middle Layer of the eye
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Uveal Tract
Lens Iris |
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Uveal Tract (normal)
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Highly vascular middle layer of the eye that provides the blood supply and nutrition to the other 2 portions of the eye
Control light absorption Secrete the aqueous humour NOTE: this is where people have problems with pressure in the eye |
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Lens (normal)
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Focuses light on the retina by relaxing and contracting muscles
Changes the shape of the lens, making it thicker or thinner (process of accommodation) Avascular, colorless, transparent, suspended behind the iris, over time it thickens NOTE: like a microscope, inability to focus leads to nearsightedness and farsightedness |
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Iris (normal)
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Contrast sensitivity
Ability to discriminate between an object and it’s background Pigmented portion of the eye Purpose is to regulate the amount of light entering the eye through dilation and constriction of the pupil Circular membrane suspended behind the cornea and immediately in front of the lens NOTE: 3d ability to look at things. Less rods and cones- takes longer for eyes to adjust reason for problems with night driving |
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Inner most layer of the eye
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Retina
Cones Rods Optic Disc Macula |
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Retina (normal)
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Semitransparent
Continuous with the optic nerve Photo-receptors that are “antennae” for the visual system Houses rods and cones Receives visual images |
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Cones (normal)
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Color sensitive
Visual activity Color vision in bright light |
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Rods
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Peripheral vision, especially in dim room
Black-white vision Rods and cones contain photopigments that produce nerve stimulation when light strikes them |
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Optic Disc
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Region where retina meets the optic nerve
Contains no light receptors therefore is known as a natural “blind spot” |
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Macula
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Oval, yellowish spot to the side of the optic disc
Contains the fovea largely composed of cones and is the area of sharpest vision Key to focusing an area of the retina and is responsible for central vision |
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Lens (changes)
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Thickens and becomes less elastic, limiting ability to change shape
Changes interfere with ability to shift focus from distant to near objects (age-related far-sightedness) Presbyopia: diminished ability to focus clearly on objects at a normal distance Results in most adults needing reading glasses at age 40-50 Yellows and becomes opaque causing cooler colors to be difficult to see Pin-point opacities develop that produce dazzle from sources of bright light Better able to distinguish between bright colors |
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Iris (changes)
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Eye color fades
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Vitreous Humor (normal)
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Clear, avascular gelatin making up 2/3 of the volume and weight of the eye
Helps maintain shape and transparencies of the eye Build up of the contributes to inraoccular pressure |
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Vitreous Humor (changes)
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Becomes less transparent
Allows light to scatter instead of highly focused Floaters Loose cells and tissues casting shadows on the retina Higher visual threshold Takes more light to be able to obtain info from the environment |
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Pupil (changes)
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Pupil diameter decreases
Direct pupil reaction to light tends to decrease resulting in much less light reaching the retina Results in: Older people need more light for readings and getting around safely indoors Decreased ability to adjust to abrupt changes in lighting Both light and dark adaptation takes more time NOTE: difficulty adjusting as quickly as when you are younger. Pupil cannot open or constrict as well as it used to be |
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Sensitivity to Glare
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Light scatters as a result of changes to the cornea, lens, and vitreous humor
Loss of peripheral vision |
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Cataracts
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Opacities on the lens as a result of protein build-up (surgical treatment)
Most common eye disorder related to aging May see halos around objects, experience blurred vision, decreased light and color perception Risk factors: HBP, Diabetes, Use of corticosteroids, excessive exposure to sunlight, excessive consumption of alcohol, family history of cataracts NOTE: haven’t been able to find one common cause |
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Glaucoma
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Increased pressure in eye and leads to degeneration of the optic nerve and blindness, if not treated
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Primary Glaucoma
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Primary open angle (POAG) or Primary angle closure (PACG)
PACG Results from thickening of the lens causing closure of the duct that allows fluid to drain out Results in eye pain, clouded vision, nausea and vomiting PAOG- most predominant Degenerative changes in the eye results in increased pressure slowly over time Medications and topic cream prescribed to inhibit vitreous humor production |
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Secondary Glaucoma
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A pathological process blocks the flow of vitreous humor from the eye
Older women are more at risk Can result in the loss of peripheral vision Occurs slowly over time Causes: inflammation, diabetes, tumors NOTE: an increase in inneroccular pressure. Making too much or not absorbing enough. Slow starting, not a lot of outward physical signs. Can only be diagnosed if getting regular vision tests |
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Diabetic Retinopathy
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Leading cause of adult blindness
Nearly every diabetic has some form of this after the 20 year mark of having diabetes Small retinal blood vessels develop small aneurysms which cause hemorrhages These block the light and damage the receptors Symptoms: Cloudy vision, seeing shower spots Treatment is laser photocoagulation NOTE: will see “floaters” much more often |
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Macular Degeneration
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Severe loss of central vision
Dry= no bleeding, no treatment 90% of the cases Cells in the macula atrophy Wet= bleeding Injection into eye to keep the vessels from bleeding, growing, laser treatment Will become functionally blind if not treated The need for increasingly bright light when reading or doing close work Printed words that appear distorted or increasingly blurred Straight lines will appear bent/curved Colors that seem washed out and dull A gradual haziness of your overall vision Difficulty seeing when moving from a bright room to a dimly lit room NOTE: want to be aware of what PT’s vision status is. Severe loss of central vision. Causes: Genetics, Smoking, Cardiovascular disease, Long term sunlight exposure The previously presented diseases account for about 98% of vision loss in those over the age of 70 |
