1. Low Vision Aids

2. 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

3. Who need rehabilitation?
Patient having some vision that patients need LV device
Patient having less than 3/60, that patient wants mobility training

4. Causes Macular degeneration Diabetic Retinopathy Glaucoma
Corneal disease
Neurological disorders Albinism RP
Optic atrophy
Achromatopsia
Retinal problems

5. Low vision Examination
Case History RR
Field
Contrast sensitivity
Glare
Trial of low vision device
Instruction
Prescription
Follow-up

6. Treatment
Optical aids
Non-optical aids
Electronic aids

7. 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

8. Angular magnification
Ratio of the angle of substance of the image formed by an optical instrument compared to the actual object . E.g.. Telescope

9. Optical Aids Telescope Spectacle Hand Magnifier Stand Magnifier
Pocket Magnifier
Prismosphere

10. Distance vision
Telescopes
Galilean
Keplerian

11. Galilean + Objective, - eye piece Low power ( 2 x to 4x )
Lighter, less expensive
Large exit pupil

12. Keplarian + objective, + eye piece Prism to invert image
Higher powers available
Poor light gathering

13. Types Hand held telescopes Clip on telescopes
Spectacle mounted telescopes

14. Hand held Portable Spotting intermediate & distance Monocular
Inexpensive

15. Clip on 2.5 x to 4 x Distance and near
Some hand held can be placed in flip-up clip

16. 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

17. Advantages of telescopes
Distance, intermediate or near
Variable working distance
Monocular & binocular
Spectacle mounted and hand held
Ideal range -2x to 4x

18. Disadvantage in Telescope
Disadvantages
Restricted field
Reduced light gathering
Limited depth of focus
Requires co-ordination
Appearance and cost factor

19. Problems with optical system
Small field of view
When magnification increases contrast will be decrease
Close working distance
Lighting and glare
More aberrations

20. 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

21. Kesten baum’s rule
The inverse of the visual acuity = the add required to read 1m point
6/60 = ds

22. Spectacle Advantages Hands free Wide field Prolonged reading
Monocular or binocular

23. Disadvantages Fixing reading distance Close reading distance
Positioning and posture
Head pain

24. 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

25. Hand Magnifier Disadvantages Reduced field of view Both hands occupied
Critical focus distance
Motion magnified ( tremor, arthritis )
Illumination reflected

26. 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

27. 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

28. Prism sphere glasses Advantages +5.0 ds & 6.0 ds, 8.0ds prismospheres
4x dome magnifier
Aspheric, ds, ds, ds
2.5 stand magnifier

29. Disadvantages
Very close Reading
Standard reading distance

30. Non Optical Aids Tints Illumination fluorescent lamp Contrast
Incandescent
Neodymium bulb
Halogen light
Contrast
Black pen
Typo scope ( black & white contrast )
Money finder

31. 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.

32. 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

33. Thank you