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Low Vision Aids. Who are all low vision patient. Having vision less than 6/18 in better eye Having vision 6/6 but field of vision is less than 20 Having vision 6/6, field of vision is normal, but contrast sensitivity is poor. Who need rehabilitation?.

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who are all low vision patient
Who are all low vision patient
  • Having vision less than 6/18 in better eye
  • Having vision 6/6 but field of vision is less than 20
  • Having vision 6/6, field of vision is normal, but contrast sensitivity is poor
who need rehabilitation
Who need rehabilitation?
  • Patient having some vision that patients need LV device
  • Patient having less than 3/60, that patient wants mobility training
causes
Causes
  • Macular degeneration
  • Diabetic Retinopathy
  • Glaucoma
  • Corneal disease
  • Neurological disorders Albinism
  • RP
  • Optic atrophy
  • Achromatopsia
  • Retinal problems
low vision examination
Low vision Examination
  • Case History
  • RR
  • Field
  • Contrast sensitivity
  • Glare
  • Trial of low vision device
  • Instruction
  • Prescription
  • Follow-up
treatment
Treatment
  • Optical aids
  • Non-optical aids
  • Electronic aids
magnification
Magnification
  • Relative size magnification
    • Physically enlarging the size of an object of the retina
  • Relative distance magnification
    • Moving the object of regards towards the patient
angular magnification
Angular magnification
  • Ratio of the angle of substance of the image formed by an optical instrument compared to the actual object . E.g.. Telescope
optical aids
Optical Aids
  • Telescope
  • Spectacle
  • Hand Magnifier
  • Stand Magnifier
  • Pocket Magnifier
  • Prismosphere
distance vision
Distance vision
  • Telescopes
    • Galilean
    • Keplerian
galilean
Galilean
  • + Objective, - eye piece
  • Low power ( 2 x to 4x )
  • Lighter, less expensive
  • Large exit pupil
keplarian
Keplarian
  • + objective, + eye piece
  • Prism to invert image
  • Higher powers available
  • Poor light gathering
types
Types
  • Hand held telescopes
  • Clip on telescopes
  • Spectacle mounted telescopes
hand held
Hand held
  • Portable
  • Spotting intermediate & distance
  • Monocular
  • Inexpensive
clip on
Clip on
  • 2.5 x to 4 x
  • Distance and near
  • Some hand held can be placed in flip-up clip
spectacle mounted
Spectacle mounted
  • 1.7x to 8x
  • Special order
  • Bioptic
  • Full diameter
  • Wide angle
  • Expanded field when compared to others
  • It is also available head down type
advantages of telescopes
Advantages of telescopes
  • Distance, intermediate or near
  • Variable working distance
  • Monocular & binocular
  • Spectacle mounted and hand held
  • Ideal range -2x to 4x
disadvantage in telescope
Disadvantage in Telescope
  • Disadvantages
    • Restricted field
    • Reduced light gathering
    • Limited depth of focus
    • Requires co-ordination
    • Appearance and cost factor
problems with optical system
Problems with optical system
  • Small field of view
  • When magnification increases contrast will be decrease
  • Close working distance
  • Lighting and glare
  • More aberrations
optical aids available here
Optical aids available here
  • Telescope 3x; 4x
  • 2x hand held magnifier
  • 2x bar magnifier
  • 3x hand held illuminated magnifier
  • Pocket magnifier ( 3x, 6x)
  • 5.0 ds hand held illuminated magnifier
  • 4x wide field stand magnifier
  • 6x cutaway stand magnifier
kesten baum s rule
Kesten baum’s rule
  • The inverse of the visual acuity = the add required to read 1m point
  • 6/60 = +10.0 ds
spectacle
Spectacle
  • Advantages
    • Hands free
    • Wide field
    • Prolonged reading
    • Monocular or binocular
disadvantages
Disadvantages
  • Fixing reading distance
  • Close reading distance
  • Positioning and posture
  • Head pain
hand magnifiers
Hand Magnifiers
  • Advantages
    • Variable eye lens distance
    • Normal reading distance
    • Allows for eccentric viewing
    • May have own light source
    • Ideal range 10 to 20 dpts
hand magnifier
Hand Magnifier
  • Disadvantages
    • Reduced field of view
    • Both hands occupied
    • Critical focus distance
    • Motion magnified ( tremor, arthritis )
    • Illumination reflected
stand magnifiers
Stand Magnifiers
  • Advantages
    • May have own light source
    • Lens distance stabilized on page
    • Ideal for stroke, tremor, arthritis patients
    • Ideal stand range 12 – 24 dpts
    • Illuminated stand range 16 to 28 dpts
stand magnifiers1
Stand Magnifiers
  • Disadvantages
    • Reduced field of view
    • Requires co-ordination
    • Need to use appropriate glasses
    • Illumination blocked and reflected by lens
    • Not be a portable
prism sphere glasses
Prism sphere glasses

Advantages

  • +5.0 ds & 6.0 ds, 8.0ds prismospheres
  • 4x dome magnifier
  • Aspheric, +16.0 ds, +22.0 ds, +24.0 ds
  • 2.5 stand magnifier
disadvantages1
Disadvantages
  • Very close Reading
  • Standard reading distance
non optical aids
Non Optical Aids
  • Tints
  • Illumination
  • fluorescent lamp
    • Incandescent
    • Neodymium bulb
    • Halogen light
  • Contrast
    • Black pen
    • Typo scope ( black & white contrast)
  • Money finder
electronic aids
Electronic aids
  • CTV – closed circuit televisions allow printed hand written and graphic material to be electronically displayed, magnified and enhanced on a television monitor. Contrast can be increased and the image polarity reversed allowing white letters to be displayed on a black back ground or the reverse. Patients also have a choice of color displatts.
how to prescribe reading glairs
How to prescribe reading glairs
  • Best refraction
  • Give correct add power for near
  • Make sure patient is reading at correct distance
  • See it lighting helps
  • Try their own reading material (eg) newspaper
  • Are prisms needed
  • If the patient is monocular
    • No prism needed
    • Occlude fellow eye if it interferes – V/A is poor
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