Vision Flashcards
Exam 2
What does visual function depend on
Visual function depends on a sequence of processes beginning with the perception of an external stimulus and ending with the processing of neural impulses into cerebral cortex.
What does the visual system consist of?
The visual system consists of the external tissues and structures surrounding the eye,
that play an important role in protecting the eye include the eyebrows, eyelids, eyelashes, lacrimal system, conjunctiva, and sclera.
The visual system consists of the external tissues and structures surrounding the eye, what role do they play?
What do they include?
The visual system consists of the external tissues and structures surrounding the eye,
that play an important role in protecting the eye include the eyebrows, eyelids, eyelashes, lacrimal system, conjunctiva, and sclera.
Internal eye structures include?
iris,
lens,
ciliary body
choroid
retina
What happens to light reflected from an object?
Light reflected from an object in the field of vision passes through the transparent structures of the eye and, in doing so, is refracted (bent) so that a clear image can fall on the retina.
From the retina, where does visual stimuli travel?
From the retina, the visual stimuli travel through the visual pathway to the occipital cortex, where they are perceived as an image.
What structures are subject to change with aging?
Every structure of visual system is subject to change with aging.
Age related changes in the nervous system and the eye support structures can reduce the visual acuity and visual function. Some changes are cosmetic- not effect vision.
Age-Related Changes in appearance and tear ducts
Changes in appearance include:
arcus senillis
loss of orbital fat,
diminished elasticity of eyelid muscles
Age-Related Changes in appearance and tear ducts
Changes in appearance include arcus senillis (photo bottom right), loss of orbital fat, and diminished elasticity of eyelid muscles
What is there impact on vision?
usually do not interfere with vision
Age-Related Changes in appearance and tear ducts
Changes in appearance include arcus senillis (photo bottom right), loss of orbital fat, and diminished elasticity of eyelid muscles
usually do not interfere with vision
What is the exception?
(*exception –Blepharochalasis-can eventually impair vision)
Age-Related Changes in appearance and tear ducts
What are other age related changes of the eye? What is treatment?
Diminished tear production (*Tx-use of artificial tears)
Age-Related Changes in appearance and tear ducts
What structures do degenerative changes of the eye effect?
Degenerative changes affect all structures of the eye, the retinal–neural pathway, and visual cortex of the brain
Age-Related Changes in appearance and tear ducts
What are corneal changes:
Changes in color of sclera
Less ability to dilate pupil
More light needed for reading)
Age-Related Changes in appearance and tear ducts
Arcus senilis: What is it?
Eventually, the arc may become a complete ring around the colored portion (iris) of the eye.
Age-Related Changes in appearance and tear ducts
Arcus senilis: What is it caused by?
It’s caused by fat (lipid) deposits deep in the edge of the cornea.
Age-Related Changes in appearance and tear ducts
Arcus senilis: What does it effect?
Arcus senilis doesn’t affect vision, nor does it require treatment.
Age related changes in the structure of the eye can affect the vision in older adults
Ciliary Body- What is it?
The ciliary body is a mass of muscles, connective tissue, and blood vessels surrounding the lens.
Age related changes in the structure of the eye can affect the vision in older adults
Ciliary Body- What do they regulate? What is there primary function?
These muscles regulate the passage of light rays through the lens by changing the shape of the lens.
Primary functions of the ciliary body are production of aqueous fluid and control of the ability to focus.
Age related changes in the structure of the eye can affect the vision in older adults
Ciliary Body- What happens with age?
Muscle cells are replaced with connective tissue, and the ciliary body gradually becomes smaller, stiffer, and less functional.
Age related changes in the structure of the eye can affect the vision in older adults
Ciliary Body-
With age, what happens with aqueous humor? What does this lead to?
With advanced age, diminished secretion of aqueous humor interferes with the nourishment and cleansing of the lens and cornea.
Age related changes in the structure of the eye can affect the vision in older adults
Vitreous- What is it?
The vitreous is a clear, gelatinous mass that forms the inner substance and maintains the spherical shape of the eye.
Age related changes in the structure of the eye can affect the vision in older adults
Vitreous- What happens with age?
With increasing age, the gelatinous substance shrinks, causing a proportionate increase in the liquid portion.
Age related changes in the structure of the eye can affect the vision in older adults
Vitreous-
With increasing age, the gelatinous substance shrinks, causing a proportionate increase in the liquid portion.
Because of these changes, what happens?
Because of these changes, the vitreous body pulls away from the retina, resulting in symptoms such as floaters, blurred vision, distorted images, or light flashes.
Age related changes in the structure of the eye can affect the vision in older adults
Retina: What is it composed of?
Because of these changes, what happens?
Composed of rods and cones which are required for color perception and acuity?
Age related changes in the structure of the eye can affect the vision in older adults
Retina:
What happens with age?
Although the number of cone cells diminishes with increasing age, the loss is primarily in the periphery rather than the fovea, and the effects are minimal.
The number of rod cells also declines, but the remaining rods increase in size and maintain their ability to capture light. Additional age-related changes in retinal structures include accumulation of lipofuscin and thinning and sclerosis of the blood vessels and pigment epithelium.
Age related changes in the structure of the eye can affect the vision in older adults
Cornea: What is it?
The cornea is a translucent covering over the eye that refracts light rays and provides 65% to 75% of the focusing power of the eye.
Age related changes in the structure of the eye can affect the vision in older adults
Cornea: What are characteristics of the cornea? What does it do? What part of the eye is it?
Smooth, clear, strong and durable;
Shields eyes from germs and dust
Outermost lens
Age related changes in the structure of the eye can affect the vision in older adults
Cornea: What happens to it with age?
Becomes opaque and yellow impairing passage of light
Lipid deposits lead to blurred vision
Altered curvature results in impaired refractility
Age related changes in the structure of the eye can affect the vision in older adults
Lens: Where is it? What does it do?
Situated behind the iris.
Focuses light onto the retina
Age related changes in the structure of the eye can affect the vision in older adults
Lens: What happens with age?
Becomes stiffer, denser, and more opaque
Age related changes in the structure of the eye can affect the vision in older adults
iris: What is it?
Colored part of the eye
Age related changes in the structure of the eye can affect the vision in older adults
iris: What does it control?
Controls light levels inside the eye (like aperture on camera)
Age related changes in the structure of the eye can affect the vision in older adults
iris: What is the round opening in the center?
pupil
Age related changes in the structure of the eye can affect the vision in older adults
iris: What is the iris embedded with? What does this do?
Iris embedded with tiny muscles that dilate and constrict pupil size?
Age related changes in the structure of the eye can affect the vision in older adults
iris: What happens with age?
Becomes less flexible and the pupil becomes smaller
Effects of age- related changes on vision
What is there a loss of:
Loss of accommodation
Diminished acuity
Reduced visual field
Diminished depth perception
Effects of age- related changes on vision
What is there a delay of? What is there an alteration of?
Delayed dark and light adaptation
Altered color vision:
Effects of age- related changes on vision
What is slower?
Slower visual information processing
Effects of age- related changes on vision
Loss of accommodation: What is the term?
presbyopia—
Effects of age- related changes on vision
Loss of accommodation: presbyopia—
What does this mean?
diminished ability to focus clearly on objects at various distances (far-sighted)
Effects of age- related changes on vision
Diminished acuity:
What does this mean?
diminished ability to detect details and discern objects
Effects of age- related changes on vision
Delayed dark and light adaptation:
What does this mean?
slower adaptive response to changes in lighting
Effects of age- related changes on vision
Altered color vision:
What does this mean?
perception blue objects look darker, and whites appear more yellowed
Effects of age- related changes on vision
What is visual impairment? What does it range from?
loss that cannot be corrected with glasses or contacts; ranges from mild to blindness
What is presbyopia?
A. The loss of accommodation
B. Diminished visual acuity
C. Delayed reaction to changes in light
D. A reduction in the visual field
A. The loss of accommodation
Presbyopia is the loss of accommodation, which is the ability to focus clearly on objects at various distances. Presbyopia is an initial and universal age-related vision change, which begins in early adulthood and affects all humans to some degree by their mid-fifties
Visual Impairment
Personal cost for older person with visual impairment
What occurs?
Loss of independence
Social isolation
Depression
Decreased quality of life
Risk Factors That affect Visual Wellness
Lifestyle, nutrition, environment: exacerbate age-related vision changes
Risk Factors That affect Visual Wellness
Factors that interfere with visual wellness:
Poor nutrition, smoking, sunlight exposure
Warmer environmental temperatures, wind, low humidity, secondhand smoke
Lighting, color contrast
Chronic conditions ( Hypertension, Diabetes, Parkinson’s LBD)
Medications
Functional Consequences Affecting Visual Wellness:
Effects on Safety, function and overall health ,QOL and Driving
Available lighting needs are three to five times more than previously required
Difficulty with Effect on driving in general
Night driving (Particularly with Glaucoma)
Increased risk for unsafe mobility and falls
Increased difficulty in performing usual activities
Anxiety, depression, and lower levels of psychological well-being
Common Disease Conditions Affecting Vision include:
Cataracts:
Age-related macular degeneration (AMD):
Glaucoma:
Diabetic retinopathy:
Common Disease Conditions Affecting Vision include:
Cataracts:
leading, reversible cause of vision impairment
Common Disease Conditions Affecting Vision include:
Cataracts: What would the patient report?
Pt. will report cloudy, hazy vision
Common Disease Conditions Affecting Vision include:
Cataracts: How does this happen?
The development of a Cataract occurs when the lens of the eye loses its transparency.
Common Disease Conditions Affecting Vision include:
Age-related macular degeneration (AMD):
leading cause of severe vision loss