CAUSES OF LOW VISION Flashcards by MECAELA AGUILLON

Common causes of low vision

Cataracts
Albinism
Diabetic Retinopathy
Corneal scarring
HIV related dse.
Optic nerve head dse.
Trauma
Retinitis pigmentosa
Glaucoma
Microphthalmos
Macular degeneration
Cortical blidness
Aniridia

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Symptoms of low vision

Distorted VA, near and distance
Restricted visual fields
Deprived night vision
Defected color vision
Severely reduced contrast sensitivity
Difficulty performing activties
Differing light levels needed
Need more time to do activties
Become tired more quickly

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Categories of low vision

Reduced VA
Reduced CS
Reduced VF

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One of the most common symptoms of eye dse. Causing low vision

Reduced VA

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Reduced VA may occur as a result of

Cataracts
Keratoconus
Microcornea
Corneal degeneration
Failed corneal graft
Dislocated lens
Aniridia
Albinism

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Effect of overall reduced VA

Reduce quality of life of persons
Affects everyday activities like reading, writing, driving

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Behavioral manifestations of reduced distance VA

Difficulty in…
Recognizing details
Learning by imitation
Orientation and mobility
Reading road signs
Driving

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Behavioural manifestations as a result of a secondary reduction in contrast sensitivity

Bumping into objects like door frames or furniture
Seeing time on a watch can be difficult
Identifying coins and currency may be problematic
Difficulty in walking down steps
Difficulty in driving and mobility in a dimly lit area
Difficulty in reading poor contrast materials like the newspaper

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Management of reduced VA

Spectacles
Telescopes for distance viewing
Magnifiers
LVAs supplemented with environmental modifications and the use of color to enhance the effects of dse. Conditions

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May occur early in disease condition when VA may not be or minimally affected

Reduced CS

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T/F
Very often patients having reduced contrast sensitivity also very sensitive to lighting and glare

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Management of reduced contrast sensitivity

Filters
Environmental modifications to enhance contrast either by adding color contrast
Lighting modifications to avoid glare
Closed-circuit televisions

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Ocular conditions resulting in central field loss:

ARMD
Best’s dse.
Stargardt’s macular dystrophy
Macular hole
Macular coloboma
Myopic degeneration
Chorioretinitis

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Produces inability to perceive objects or people in direct line of sight

Central visual field loss

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Type of central VF where the center is only blurry

Central relative scotoma

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Type of central VF where the center is complete dark

Central absolute scotoma

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Behavioural manifestations that may occur as a result of central field loss

• Not talking directly to people

• Unusual head position

• Lack of eye contact

• Diminishing ability to recognize people in front of them

• The secondary reduction in VA may produce difficulties in reading and writing

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Behavioral manifestation of poor color vision

• Inability to identify colour of objects

• Uncoordinated clothing

• Sorting fruits and vegetables difficult

• Issues identifying medicines

• Identifying food on plate difficult

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Management for central VF

Training eccentric viewing
Low powered magnifiers
Fresnel prisms
Line guides

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Affects the individual’s ability to perceive people or objects to the sides

Peripheral field loss

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Vision is partially obstructed or non-existent in the affected field

Peripheral field loss

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Ocular conditions producing peripheral field loss

Retinitis pigmentosa
Glaucoma
Leber’s congenital amaurosis
Optic atrophy
Lasered diabetic retinopathy
ROP
Retinal detachment
Multiple sclerosis

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Behavioral manifestations in response to peripheral field loss

Unusual head movements
Difficulty in reading
Uncertainty in mobility
Inability to find lost objects

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Behavioral manifestation in partial blurred vision

Difficulty in reading and writing
Difficulty in recognizing details
Difficulty in reading road signs
Difficulty in orientation and mobility

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Management of peripheral field loss

Orientation and mobility Reverse telescopes Minus lenses Fresnel prisms Mirrors

Diseases in the anterior segment of the eye

Cataract Corneal dse.

Clouding of the crystalline lens

Cataract

CLINICAL PRESENTATION - Visual loss due to clouding of lens - The denser the clouding, the greater the level of VI

Cataract

Opto management for cataract

UV sunglasses Avoid smoking Good diabetic control

Dystrophy in which structural changes within the cornea cause it to become thin and change from the normal curve to a more conical shape

Keratoconus

CLINICAL PRESENTATION - Refractive errors (usually myopic astigmatism) - Blurred or distorted images - Glare, Cloudy vision and reduced VA

Keratoconus

Opto management for keratoconus

Contact lenses

caused by an infection of the ocular surface by a bacterium (Chlamydia trachomatis serotypes A-C)

Trachoma

can cause severe inflammation of the ocular surface resulting in scarring of the eyelids

Trachoma

Also known as river blindness

Onchoceriasis

caused by filarial nematode Onchocera volvulus - worm transmitted by the Simulium black fly which breeds in rivers and stream of Africa

Onchoceriasis

can result in xerophthalmia (severe dryness) and lead to complication at the anterior and posterior segments of the eye

Vitamin A deficiency

Management on Vit. A deficiency

Vit. A supplements

Most common type of glaucoma

Open angle G

decreased aqueous drainage caused by a dysfunction or clogging of the trabecular meshwork resulting to elevated eye pressure

Open angle g

CLINICAL PRESENTATION - Irritation due to dryness - Scarring of the cornea - Ulceration and Perforation (Keratomalacia) - Night blindness may occur

Vitamin A deficiency

CLINICAL PRESENTATION - Conjunctivitis - Corneal Scaring - Uveitis - Glaucoma

Onchoceriasis

“Acute glaucoma”

Closed angle G

occurs when angle between the cornea and iris closes abruptly. With this, fluid can’t access the drainage pathway, causing an increase of eye pressure rapidly.

Closed angle G.

CLINICAL PRESENTATION - may not notice any symptoms until severe visual damage has occured

Open angle G.

Clinical Presentation - red, painful eye with disturbance of vision

Acute angle closure

Blood vessels fail to transport food, waste and oxygen

Ischemia

Blood vessels leak blood or fats causing damage to the retina

Leakage

Blood vessels can cause massive hemorrhages or retinal detachment

Abnormal shape

caused by degenerative changes to the central area of the retina causing gradual or sudden loss of vision

ARMD

TYPE OF ARMD WHERE PROGRESSION IS SLOW

Dry ARMD

Type of ARMD where there is leaking of blood vessels underneath retina

Wet ARMD

most common cause of INHERITED BLINDNESS

Retinitis Pigmentosa

progressive loss of photoreceptor cells

Rod photoreceptors are affect first thus night blindness is typically the first symptom

deficiency in the pigmentation of the skin and hair, as well as the iris and retina

Albinism

trait inherited through autosomal recessive or sex-linked transmission

Albinism

CLINICAL PRESENTATION - Night and peripheral vision - go hand in hand - the more advanced, the smaller the visual field (tunnel vision)

Clinical Presentation - difficult to move around safely as visual field becomes smaller and central retina becomes involved

Opto management for Albinism

- corrective spectacle lenses as well as absorptive lenses to reduce photophobia.

also known as cortical blindness

Cortical visual impairment

disorder caused by damage to the parts of the brain that process vision

Cortical visual impairment

Causes of cortical visual impairment

Behavioral manifestation of reduced near VA

Reading and writing Grooming/self care Peparing food and eating Using computers Signing documents Arts and crafts

CAUSES OF LOW VISION Flashcards

(64 cards)