Deaf-Blindness: Etiology and Overview

Deaf-Blind Definition

  • Central visual acuity of 20/200 or worse with corrective lenses or a visual field of 20 degrees or less.

  • Progressive visual loss.

  • Chronic hearing loss where speech isn't understood with amplification or progressive hearing loss.

Considerations

  • Age of onset is important for adapting to dual sensory loss.

Genetic Disorders

  • Usher Syndrome, CHARGE, NF2 (neurofibromatosis)

Usher Syndrome Types

  • Type I: Profound congenital hearing loss and retinitis pigmentosa with night blindness and progressive vision loss. Balance problems.

  • Type II: Mild to severe hearing loss, retinitis pigmentosa, stable hearing, normal vestibular function.

  • Type III: Progressive hearing loss, visual symptoms similar to Type I, variable vestibular function.

Retinitis Pigmentosa

  • Visual Symptoms: Night, peripheral, and central vision loss; cataracts. Rods decrease between 0-20 years; cones between 5-40 years; central vision may decrease from 45 to about 5 between 20-50 years. Lens clouding also occurs.

Accommodations

  • Reduce glare, provide additional light, allow time for light adjustment, use human guides, avoid clutter, use contrasting clothing, offer smaller signing spaces, tactile signing, increased magnification, voice output/Braille.

CHARGE Syndrome

  • Rare genetic disorder associated with DeafBlindness.

  • C: coloboma, cranial nerve damage, cleft lip/palate; H: heart defects, hearing loss; A: atresia of the choanae; R: retardation in growth/development; G: genito-urinary defects, gastrointestinal issues; E: endocrine system, ear anomalies.

NF2 (neurofibromatosis)

  • Affects cranial and spinal nerves, causing hearing loss, tinnitus, balance, and vision problems due to benign tumors.

Other Visual Conditions

  • Scotoma, Macular Degeneration, Cataracts, Glaucoma, Diabetic Retinopathy, Retinopathy of Prematurity, Hemianopsia, Optic Atrophy

Visual Conditions Specifics

  • Macular Degeneration: Loss of central vision.

  • Cataracts: Clouding of the lens.

  • Glaucoma: Vision loss from increased intraocular pressure.

  • Diabetic Retinopathy: Affects retinal blood vessels, causing vision loss, light sensitivity, blind spots, color blindness.

  • Retinopathy of Prematurity: Affects babies less than 2342 \frac{3}{4} lbs. at birth.

  • Hemianopsia: Loss of half the visual field.

  • Optic Atrophy: Loss of optic nerve tissue, fluctuating vision.

Syndromes with Hearing Loss and RP (Not Usher)

  • Alstrom, Bardet – Biedel, Cockayne, Flynn – Aird, Kearns – Sayers, Refsum

Other Causes of Deaf-Blindness

  • Congenital Rubella, Norrie Syndrome, TBI, Stroke, Fetal Alcohol Syndrome, Prematurity

Auditory

Hearing Loss Types

  • Conductive: Barrier in outer/middle ear.

  • Sensorineural: Damage to inner ear/auditory nerve.

  • Central: Damage to brain affecting auditory processing.

Degree of Hearing &