Low vision devices optical and non optical

Presentation on Low vision devices: Optical and non-optical for BSEd of Bangladesh Institute of Special Education

1. Low vision devices: Optical and non-optical BSEd Nusrat Zerin

2. Low vision devices: Tools that help those with vision loss maximize their remaining vision and these devices are: Optical Non Optical Electronic devices

3. Check that each person has been examined to see if spectacles are needed to correct /improve vision before recommending low vision devices . Before selecting a low vision device consider: size of objects to be viewed possible viewing distance from the object length of time needed for activity Whether one / both hands are needed for activity

4. Optical devices are – Near: These are designed for magnifying close objects & print. Spectacles Magnifiers – Hand held & Stand magnifiers, illuminated magnifiers 2. Distance: These are for magnifying things in the distance (from 3 metres to far away). Monocular Binocular Telescope 3. Electronic devices: CCTV or video magnifier

5. Optical devices are – Near: These are designed for magnifying close objects & print. Spectacles Magnifiers – Hand held & Stand magnifiers, illuminated magnifiers (Dome, Bar, Sheet magnifiers) 2. Distance: These are for magnifying things in the distance (from 3 metres to far away). Monocular Binocular Telescope 3. Electronic devices

6. Optical devices for near tasks Magnifiers for near tasks can be used for: reading a book or a newspaper reading labels, signs or prices in shops using tools, for example measuring threading a needle identifying money inspecting objects such as plants or insects For reading, the magnifier has to be moved along each line of print, sometimes only showing a word or part of a word at a time. More words will be seen if the eye is held close to the magnifier. Reading is very slow at first. It is difficult to learn to use the magnifier properly - a lot of practice is needed.

7. 1. Uses: for reading any material writing looking at objects from close range 2. Advantages: range of magnification both hands free readily available- e.g."cataract " glasses can be used as reading glasses once used efficiently, can be used for long periods 3. Disadvantages: exact reading distance important Short reading distance with high powered lenses more fragile than magnifiers (scratching, breaking) Bad lighting at close distance stress eye Without reading stand to bring material close to eye is difficult

8. Hand Magnifiers 1. Uses: reading signs, labels, prices, books identifying money inspecting objects such as plants or insects handwriting 2. Advantages: easy to carry available from low to high power Less expensive can be used in any position or angle Illuminated magnifiers allows light onto print or objects 3. Disadvantages: difficult to keep appropriate distance one hand occupied difficult to hold steady

9. Stand Magnifiers A stand magnifier is a strong lens which is mounted in a plastic stand. A stand magnifier is usually easier than a hand held magnifier for a child to use. 1. Uses Reading from a book or newspaper Looking at a picture or diagram 2. Advantages Has a fixed distance for ease of movement Easy to use Available from low to high power magnification Allows light onto print if legs thin and tapered or clear 3. Disadvantages Keeps one hand occupied Not useful for activities like writing Poor posture (bending above lens) Causes fatigue

10. Optical devices for Distance task Magnifiers for distance are like small telescopes. They improve the ability to see distant objects or people. Objects appear to be closer and it is hard to judge distances properly. It is best not to use telescopes while walking around. Telescopes Telescopes can be used for looking at distant objects and activities such as: signs finding and recognizing people/animals Reading in school from blackboard finding an entrance to a building watching games.

11. 1. Uses Reading from a blackboard from a distance >2 /3m Looking at objects you cannot get close to, e.g. top of a tree, animals 2. Advantages Makes distant objects appear closer Can be used in a classroom for blackboard reading or outdoors 3. Disadvantages Requires very good contrast Takes time to: Find text on blackboard and read Write notes down, possibly using other low vision device Expensive to make Not easy to use, requires extensive training

12. Training to use optical devices Encouragement and training are needed for people to use low vision devices well. The field of view or amount through magnifier or telescope is small. It takes practice to be able to find objects and then follow them or scan to find other objects. For distance tasks it is best to look in the general direction of an object without the device and then point or place the device in that direction to locate objects. It is easier to scan along horizontal objects such as roads or fences and up and down vertical objects such as trees or walls. Do not just give out magnifying glasses, if there is no one to train the person in its use. A person will often reject the device, because they do not know how to see better with it. Training in the use of all magnifying devices is vital

13. Non Optical devices: Reading stand Felt tipped pen, markers Sun glasses Caps/Sun visors Table lamps