Vision

symptoms of retinal detachment

flashes of light, vision loss, the sensation of looking through a veil or curtain. A person experiencing these symptoms should seek immediate medical attention.

Tiny specks that float across the field of vision Generally most aware of them when they are in well lit rooms or outdoors on a bright day Often normal but sometimes indicate an eye problem

floaters

how can vision loss be prevented with glaucoma

If the pressure is normalized prior to the optic nerve being damaged, vision loss can be prevented

Role of CVRT

--Use of braille, ADL, home management, communication systems, medical management, leisure & recreation, psychosocial adjustment, basic orientation & mobility --instruct persons with vision impairments in the use of compensatory skills and assistive technology that will enable them to live safe, productive, and interdependent lives. --Adjustment counseling

what does having 20/20 vision mean? what does it mean if you have 20/100?

--you can see clearly at 20 feet what should normally be seen at that distance. --you must be as close as 20 feet to see what a person with normal vision can see at 100 feet.

legally blind if ___/___ or ___ % field

20/200 best correction in better eye, or 20 degree field or less in better eye

Disease that causes progressive deterioration of the cells of the macula and fovea in the center of the retina.

AMD

Leading cause of visual impairment among adults in US

AMD

warning signs of retinal detachments

Among the possible warning signs of a retinal detachment are dark or fuzzy "floaters" in the visual field and flickers or flashes of light

assessment for vision to monitor changes in visual status for AMD

Amsler Grid

How to Increase ability to identify objects

Bold colors - easy identification Contrast enhancement - identification of one item against another, i.e. use bold blue hand towel instead of white against bathroom counter top Integration of other senses - auditory, tactile, i.e. - bump dots, colored rubber bands

Train patients to use optical and non-optical devices Visual skills training Environmental modification Strategies for efficient use of vision Visual perception training and compensatory strategies

CLVT (Certified Low Vision Therapist)

Train integration of compensatory low-vision techniques & vision-oriented assistive technology

CVRT (Certified Vision Rehabilitation Therapists)

is characterized by visual disturbances usually occurring in people who have experienced visual impairment or sight loss later in life, as through macular degeneration

Charles Bonnet Syndrome

may see a wide range of images, from simple patterns to people, animals, and buildings. The visual disturbances associated with this syndrome are not signs of mental illness, and people realize that the images they are seeing are not real.

Charles Bonnet Syndrome

Progressive optic nerve changes Resistance to fluid movement increasing intraocular pressure Loss of peripheral vision Damage to blood vessels, blurred vision, color discrimination, range from "spotty" field losses to complete blindness changes in blood vessels

Diabetic Retinopathy

Spots in vision is an example of the vision of which visual diagnosis?

Diabetic Retinopathy

Four major causes of low vision are directly related to the aging process:

Diabetic retinopathy Age related macular degeneration Cataracts Glaucoma

Patterns of vision loss with Cataracts

Dulls colors and blurs visual detail Eventually compromises distance and near vision

what assessment for acuity? Last row where pt can read 5 letters correctly letters are spaced and balanced according to difficulty, and same number of letters per row

ETDRS - Early treatment diabetic retinopathy study = gold standard

light is focused perfectly on retina; normal sighted

Emmetropia/ic

Diabetic Retinopathy (DR) pathology

High levels of glucose in the bloodstream cause damage to small blood vessels At 20 years after the onset of diabetes, up to 99% of persons with Type 1 diabetes & 60% with Type 2 diabetes have DR to some degree. Affects entire retina & can cause any level of vision loss, including total blindness Only common eye disease that can cause varying patterns of vision loss because it affects the blood vessels that support the entire retina. May place clients at risk for developing other common eye conditions Involves a continuum of pathology beginning with non proliferative form or background diabetic neuropathy (BDR)

Which would be the least effective way to modify reading for someone with severe glaucoma

Integrate task lighting Reduce overhead lighting to lessen glare & shadows Encourage books on tape for less eye strain Enlarge print at least 2x Minimize amount of words and letters on a page

Environmental modifications - to facilitate safety/task performance

Lighting - nightlights, natural light, power of bulbs Organize: declutter, group items for less perceptual & scanning demands Contrast: sizes and shapes, bold colors against light Color: Red/Black, bold/dark colors Pattern - reduce use of patterned items, use consistency w/labels & modifications throughout home Glare reduction - matte paint, avoid glare on screens or floors Print size - alter to improve performance or seek CLVT to train use of optical devices

How to optimize residual vision

Optical aids - Glasses, prisms, magnifiers Visual skills - Scanning & Oculomotor skills (pursuits, saccades)

Train in orientation techniques teaches a variety of techniques and methods, including white cane use, to train patients to be safe in the community. They teach patients how to route plan, cross streets, use a human guide, utilize landmarks, and other ways to negotiate their environments safely.

Orientation and Mobility Specialist (COMS)

risks of visual impairments

Patients with visual impairment have higher mortality rates and are more prone to accidents and falls. Low vision is a well-documented risk factor for hip fractures in the elderly resulting from falls.

reading test to determine speed if you multiply the words per minute average by 1.6 you will have the number for meaningful words per minute read which equates to reading a book, menu, or any other meaningful print in opposition to random words on the assessment. It was originally created for people with AMD but more recent research confirms utility for acquired brain injury and other diagnoses- it is also pattern-based, so you are able to determine functional implications of the diagnosis and what equipment, strategies, or referrals you can recommend for improved occupational performance

Pepper

Normal Visual Changes Associated With Aging:

Reduced Visual Acuity Presbyopia (diminished focusing power) Luminance (need for more light) Sensitivity to Glare Difficulty with Light/Dark Adaptation Reduced Sensitivity to Color Perception & Contrast Reduced Depth Perception Floaters Dry eyes

how is visual acuity assessed?

Snellen or ETDRS chart

Sharpness of vision the focus of light on the retina Measured by the ability to discern letters or numbers at a given distance according to a fixed standard

acuity

person previously had vision- likely has visual memories for reference

adventitious

Deterioration of retina and supportive structures Loss of central vision Progressive

age-related macular degeneration (AMD)

mild, moderate, severe (stage 1-3) vision pathology

all non-proliferating meaning microaneurysms occur at this level & some blood vessels that nourish the retina are blocked More severe (grade 3) results in signals sent to the body from the retina indicating the needs nourishment and to begin growing new blood vessels.

diffuse arrangement of light projected on retina due to asymmetrical eye shape that distorts vision

astigmatism

term to be used only for total vision loss and for conditions where individuals have to rely predominantly on vision substitution skills.

blindess

Lens changes May appear cloudy Increased density and rigidity of lens Loss of color/shading discrimination Reduced contrast sensitivity Increased glare sensitivity

cataracts

cells for sense of color and fine details

cones

blindness present from birth (no concept of vision)

congenital

anterior segment of eye

cornea aqueous humor iris lens & colliery muscle

eye adapts more quickly from ____ to _____

dark to light

Leading cause of adult blindness in the US

diabetic retinopathy

type of AMD :usually vision loss is gradual

dry

Progressive optic nerve changes Resistance to fluid movement increasing intraocular pressure Loss of peripheral vision pressure in eye resulting from blocked ducts- this, in turn, presses on the optic nerve and compresses it resulting in progressive loss of peripheral vision which is referred to as "tunneling vision" Optometrists and ophthalmologists measure this through tonometry which is the test that feels like a puff of air in each eye, or for more sensitive results they numb the eye and press a small gauge on your eye to assess pressure

glaucoma

How do you test acuity if unable to use chart?

gross assessments based on clocks, tv screens, or newspaper

farsightedness/unable to see up close

hyperopia

light focused past the retina

hyperopia

risk factors for retinal detachment

include previous eye surgery, nearsightedness, a family history of retinal detachments, uncontrolled diabetes, and trauma.

if glaucoma left untreated can ___

leave affected eye with only a narrow tunnel of vision or, in some cases without any vision. Because if affects central vision only in late stages, can be advanced in the presence of near normal acuity on a vision

People with _______ such as in _____ have very limited functional vision in dim lighting

limited visual fields (ex. advanced glaucoma),

Uncorrectable vision loss that interferes with performance of daily activities

low vision

to be used for lesser degrees of vision loss, where individuals can be helped significantly by vision enhancement aids and devices. Per the National Eye Institute (NEI): A visual impairment that is not correctable by standard eyeglasses, contact lenses, medication, or surgery and that interferes with the ability to perform everyday activities. difficulty seeing someone from a distance of 12 feet or reading a newspaper despite the use of corrective lenses.

low vision

AMD often causes

low vision clearly demarcated central blind spot (scotoma)

OT intervention goal

maximize usable vision through modifications of Objects, Environment, Tasks, & Routines

adaptions for cataracts

may require environmental adaptations to address contrast sensitivity, lighting, and glare

glaucoma has a distinctive pattern of vision loss: It begins by reducing vision in the _____ and then progresses toward the ______ reducing or eliminating the vision.

midperipheral visual field center & the periphery,

What classification of vision: able to read with text moved closer to face, difficulty with fine print, requires scanning, peripheral vision difficulties

mild low vision

what vision classification: difficulty reading for long periods of time (headaches, eye strain...), use magnification devices, compensatory scanning strategies are required if peripheral vision is involved

moderate low vision

light focused anterior to the retina

myopia

nearsightedness /unable to see far objects

myopia

what vision classification: Cannot read, relies on light and shadows, verbal communication and braille-- must use cane and/or guide dog- will require COMS for community interaction

near blindness

what assessment of acuity is most important?

near vision (we do most activities up close & poor performance could look like poor cognition)

stage 4 low vision pathology

new blood vessels form, but are weak and more likely to rupture. If they rupture, this could cause severe vision loss, even blindness. The blood vessels grow into the vitreous, block light transmission,a nd result in more severe scotoma formation, which are inconsistent and vary based upon health factors, such as blood pressure or sugar levels.

findings in vision loss & comorbidity study

older adults with visual impairment frequently experience comorbid conditions, and that these conditions are associated with difficulties in walking and climbing steps, shopping, and socializing, and with significantly more self-reports of declining health. Results suggest that interventions by health care and mental health providers, as well as enhanced rehabilitation services, have the potential to reduce or prevent the deleterious effects of comorbid conditions.

Standard placement of eye chart

on wall 20 ft away

visual system pathways

optic nerves & optic tracts lateral geniculate nucleus visual cortex

protective structures of the eye

orbit lens sclera

Condition in which near visual acuity is decreased because of age related decline in accommodative ability diminished focusing power

presbyopia

what vision classification: spot reading with devices, assistance with mobility, requires training with sight cane or guide dog for mobility

profound low vision

neovascularization

proliferation of new vessels on the surface of the retina (DR)

neovascularization Do not contribute more oxygen, instead often break and bleed Hemorrhage can extend into vitreous and cause clear gel to become opaque resulting in sudden, severe vision loss Further complication, pulls retina resulting in traction retinal detachment = requires surgical intervention

proliferative DR

blood leaking into the retina creates spotty "swiss cheese" vision. Patients have a difficult time adapting to their blind spots because they change based upon factors such as blood sugar and blood pressure.

proliferative diabetic retinopathy

How does ability to adapt to darkness slow significantly with age (3 ways)

pupil size, amount of light reaching the retina, thickening of lens

loss of a quarter of field of vision

qudrantanopsia

visual info received through ____ via ___ and sent to _____ for processing

retina optic nerve CNS

posterior segment of eye

retina vitreous humor

floaters accompanied by light flashes could indicate

retinal detachment

cells sensitive to presence of light & motion

rods

Scattered spotty areas of vision loss, called

scotomas

Patterns of vision loss with DR

scotomas May have decreased contrast sensitivity & color discrimination, poor night vision & fluctuations in vision May experience diplopia from neuropathy that affects the 3rd or 6th cranial nerves (usual resolves spontaneously)

reads slowly and uncomfortably (results in frustration and depression without additional adaptation training)

severe low vision

for rehabilitation of AMD, important to identify

size & location of the scotoma & the position of the next best spot to use when the center of the macula is damaged.

contributors to AMD

smoke & smoking, air pollution, sunlight, & insufficient nutrition contribute to AMD Predisposition toward developing the disease combined with environmental exposure & nutritional factors Free radicals damage tissues triggering an inflammatory response and further damage with eventual lack of delivery of oxygen and clearing of waste material. Retinal pigment epithelium (RPE) cells beneath the macula die first and then the photoreceptor cell die.

What assessment for acuity? 50% of letters read is equivalent to measurement of acuity

snellen

Amount of light reaching_______ decreases with age Older people receive reduced light through _______ On average, older person requires ___ times more light than a younger person Person age 80 and older requires ___ times more light than the average 25 year old

the back of the eye smaller pupil & increased density or haziness with aging lens 4 times 10 times

wet AMD can result in

total blindness

what vision classification: total loss- require the Certified Orientation and Mobility Specialist (COMS) training with white cane, pure adaptation training for occupational participation- most likely to result in occupational alienation secondary to poor adaptation

total blindness

Role of CLVT

uses functional vision evaluation instruments to assess visual acuity, visual fields, contrast sensitivity function, color vision, stereopsis, visual perceptual and visual motor functioning, literacy skills in reading and writing, etc. as they relate to vision impairment and disability. The CLVT also evaluates work history, educational performance, ADL and IADL performance, use of technology, quality of life and aspects of psychosocial and cognitive function.

refers to individuals who reported that they have trouble seeing, even when wearing glasses or contact lenses, as well as to individuals who reported that they are blind or unable to see at all..

vision loss

to be used when the condition of vision loss is characterized by a loss of visual functions (such as visual acuity, visual field, etc.) at the organ level. Many of these functions can be measured quantitatively.

visual impairment

characterized by development of a cluster of blood vessels under the macula; vessels do not belong there & they leak fluid & blood, flooding cells of the macula & RPE resulting in cell death; can occur abruptly; 10% of AMD

wet