Types of Visual Impairments

Albinism

Lack of pigmentation in the eyes, skin, and hair results in moderate to severe visual impairment by reducing visual acuity and causing nystagmus

Cause of Albinism

Heredity

Characteristics of someone with albinsim

Photobic and eye-fatigue for close work

Another term for Amblyopia

“Lazy-eye”

Amblyopia

Reduction in or loss of vision in the weaker eye from lack of use

Cause of Amblyopia

strabismus, unequal refractive errors, or opacity of the lens or cornea

Result for someone w/ Amblyopia

Close work: eye fatigue, loss of place, poor concentration

Educational approach amblyopia

seating should favor functional eye

Astigmatism

Distorted or blurred vision due to irregularities in the cornea or other surfaces of the eye that produce images on the retina not in equal focus (refractive error)

astigmatism characteristic

Loss of accommodation when object brought close to the face;

educational approach for astigmatism

avoid long periods of reading or close tasks that cause discomfort;

symptoms for astigmatism

headaches and fluctuating vision

Cataract

Blurred, distorted, or incomplete vision caused by cloudiness in the lens

Cause of astigmatism

injury, malnutrition, or rubella during pregnancy, glaucoma, retinitis pigmentosa, heredity, aging

approach for cataract

Avoid glare of any kind; light source behind child; good contrast between print and paper; variation in near and distant tasks can prevent tiring

Color deficiency/blindness

Difficulty distinguishing certain colors

red-green difference

most common confusion with color deficiency/blindess

approach for color deficiency/blindness

teach alternative ways to discriminate objects usually identified by color

Cortical Visual Impairment (CVI)

impaired vision due to damage to or malfunction of the visual cortex and/or optic nerve

cause of CVI

e anoxia, head injury, and infections of the CNS

Characteristic and Symptoms of CVI

• children have additional disabilities such as cerebral palsy, seizure disorders and ID

• Visual functioning : fluctuate depending on lighting conditions and attention

• vision usually does not deteriorate; improvement sometimes occurs over a period of time

• some children with CVI use their peripheral vision

• some are photophobic; some are attracted to bright light

• may fail to blink at threatening motions; visual images should be simple and presented singly

Diabetic Retinopathy

Impaired vision as a result of hemorrhages and the growth of new blood vessels in the area of the retina due to diabetes

Diabetic Retinopathy prevalence

leading cause of blindness in adults

approach for Diabetic Retinopathy

Provide good lighting and contrast; magnification; pressure to perform can affect blood glucose

Glaucoma

Abnormally high pressure within the eye due to disturbances or blockages of the fluids that normally circulate within the eye

Symptoms of Glaucoma

• vision is impaired or lost entirely when the increased pressure damages the retina and optic nerve

• Fluctuations in visual performance

• bulging eyes

Approach for glaucoma

• being alert to symptoms: visual performance

• scheduled eye-drops

• child monitor and support (prevention for discrimination due to eye appearance)

Hyperopia

Difficulty seeing near objects clearly but able to focus on distant objects

Cause of hyperopia

a shorter than normal eye that prevents light rays from converging on the retina (refractive error)

Characteristic of hyperopia

Loss of accommodation when object brought close to face

approach for hyperopia

• avoid long periods of reading or close tasks that cause discomfort

• glasses

Macular Degeneration

Central area of retina gradually deteriorates

characteristic & symptoms of macular degeneration

• loss of clear vision in the center of visual field

• reading and writing are difficult

approach for macular degeneration

• prescribed low-vision aid or closed-circuit TV

• good illumination; avoid glare

prevalence for macular degeneration

common in older adults, rare in children

Myopia

Distant objects are blurred or not seen at all but can see near objects clearly

cause of myopia

elongated eye that focuses images in front of the retina(refractive error)

approach for myopia

• wear prescribed glasses or contact lens; for near tasks

• child may be more comfortable working without glasses

• bringing work close to their face

(Hypothetical) risk for myopia

lack of natural light exposure

Nystagmus

Rapid, involuntary, back-and-forth movement of the eyes, which makes it difficult to focus on objects

characteristic & symptom of nystagmus

• two eyes cannot focus simultaneously- the brain avoids a double image by suppressing the visual input from one eye

• the weaker eye can lose its ability to see

• can occur on its own/ associated w/ other V.I

approach for nystagmus

• Close tasks for extended period can lead to fatigue

• children turn or tilt head to obtain the best focus

• do not criticize bhvrs

Retinitis Pigmentosa

The most common genetic disease of the eye

Characteristic & symptom of RP

• Gradual degeneration of the retina

• 1: difficulty seeing at night

• 2: loss of peripheral vision

• Hereditary

approach for RP

• High illumination with no glare

• contrasting visual field causes difficulties scanning and tracking

• skills necessary for tasks such as reading

• teach student to locate visual objects with systematic search grid

• (progressive V.I) curriculum should include mobility training, especially at night, and braille training if prognosis is loss of sight

Retinopathy of Prematurity

• caused by administering high levels of oxygen to at-risk infants.

• change in oxygen levels= producing abnormal dense growth of blood vessels and scar tissue in the eyes

• V.I & total blindness

approach for RoP

• High illumination, magnifiers for close work

• telescopes for distance viewing

• students may have brain damage resulting in intellectual disabilities and/or behavior problems

Strabismus

• Inability to focus on the same object with both eyes due to an inward or outward deviation of one or both eyes.

• Secondary to other V.I

cause of strabismus

muscle imbalance

approach for strabismus

• seating favor child’s strong eye

• one eye for distance task, other for near tasks

• close work= frequent rest periods

• more time adjusting to unfamiliar visual tasks