Types of non- optical devices
- Relative size and larger assistive devices
- Glare, contrast, and lighting control device
- Posture and comfort maintenance device
- Handwriting and written communication devices
- Medical management devices
- Orientation and mobility management techniques and devices
- Sensory substitution devices
- Relative size and larger assistive devices :
- LARGE PRINT – largest category
Large size : 14-15 point type
Also involve the spatial layout of the print
Photocopy machine
Computer with large print font
Books , magazines, newspaper, atlas etc.
- Glare , contrast, and lighting control device :-
- 0
- Also by patients with albinism, achromatopsia, retinal cone , optic atrophy etc
- Light through window or indoor lighting :source of glare.
- Illumination:
- Wall attached lamp/overhead reading lamp
- Halogen light – high intensity
- Incandescent light- longer wavelength -more contrast
- Shades :
- Caps ,hats ,visors
- Filters :
- Reduce both disability and discomfort glare
- Enhance contrast by reduction of glare and scattering
- Refraction medium to correct refractive error
- Mirror coating :
- Reduce transmittance by absorption & reflection
- Pinhole :
- Pinhole reduce blue circle in media opacities, corneal involvement , cataracts
- Stenopaic slits :
- Placed horizontally , control illumination
- Other relative size devices
- Large size telephone dial
- Large print cheques
- Large bead pins for sewing
- Watches for large faces etc
- ADVANTAGE – easy acceptance , combined magnification when used with low power optical device
- DISADVANTGES – limited magnification , not available easily , additional space needed , thicker book, expensive
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