Guidelines for prescribing optical devices and training

1. Guidelines for prescribing optical devices and training 23 February 2012

2. Session outcomes • At the end of the session, each student is expected to: • Discuss the factors which need to be considered before choosing an appropriate device • Discuss guidelines and factors to consider before prescribing telescopes • Discuss guidelines and factors to consider before prescribing near magnifiers

3. Discuss problems which may be encountered with devices • Discuss the training of a prescribed device

4. Special considerations • Patient’s level of motivation • The examiner may pick-it up during examination • Other patients may require encouragement. • The size and working distance of the task • Hands-free • Does the patient require to have hands free to hold a book/paper? • Can he/she have the text mounted on a stand?

5. Ability to hold steadily • Does the patient has ability to hold material steadily • Will the hand-held device be appropriate for this patient? • Ease of handling • Need for a flat surface • E.g. reading newspapers needs a flat surface, but reading a can won’t require fixed focus stand magnifier.

6. Acceptable cosmesis • Does the patient like the cosmesis of the device? • Will the patient mind using the device in public? • Training involved • High reading addition? • Is eccentric viewing necessary? • Environment • Close working distance • It is more acceptable to younger or highly motivated patients.

7. Portability • Does the aid need to be portable? • Or it should not be too bulky • Integral lighting • Devices which require electricity cannot be prescribed for a patient who lives in a village where there’s no electricity. • Cost • Affordability should be considered.

8. Other factors include • Age of the patient • Preference • VA of the patient

9. Distance optical devices (telescopes) • They provide an increase in the retinal image size- better resolution • Magnification should be as low as possible • To avoid limitations of field • To avoid aberration • The amount magnification depends on best VA and target acuity.

10. Sequence for prescribing telescopes • Determine the best distance correction • Measure the best corrected acuity • Determine the goal acuity • Calculate the magnification needed • Demonstrate the appropriate telescope to the patient • Explain the available options • Loan a device for home trials • Design the final prescription

11. Problems with the use of telescope may be due to the following: • May be improperly focused • May be misaligned with the eye • May be due to the patient’s poor localization skills • May be causing insufficiency of brightness • May be too close to or too far from the patient’s eye

12. Training includes • The use of the device (s) effectively in terms of: • Working distance • Posture • Handling of the device • How to take care of device

13. Head and eye movement • Eye hand coordination

14. Training with the distance devices • Familiarization with focusable devices • Focusing • Locating the object • Fixating the object • Spotting the object • Tracing the object • Tracking the object

15. 8. Scanning 9. Integration

16. Hand-held telescopes • Have px to look at the object without the telescope, • Then move the head down along straight line to look at their own feet. • Then raise the head slowly in the direction of the object with telescope before the eye. • The back-and-fourth motion along a straight line will bring the image into focus.

17. The poorer eye may be covered with a patch to allow concentration. • Do not try to walk around while looking through the telescope. • If there’s a problem with lighting or glare, the px must try to reposition him/herself. • Practice for about 5-10 (mins)

18. Sequence for prescribing hand-held and stand magnifiers • Determine the best distance correction • Measure the best corrected acuity through appropriate add • Determine the goal acuity • Calculate the magnification needed • Demonstrate the appropriate telescope to the patient • Loan a device for home trials • Demonstrate different options in which it can be prescribed.

19. Other important factors which need to be taken into consideration • Working distance • Field of view • Illumination • Device manipulation

20. Working distance • Train the patient to position and maintain the material at the proper distance. • The use of reading stands may have to be considered • Most low vision aids impose working distances to which the px is not accustomed.

21. Hand-held magnifier • Place the aid on the reading material and slowly and slowly move it towards you until words get blurred, and then push the aid away you get focus. • View from the centre of the magnifier- for good field of view • Adjust the light to properly illuminate material.

22. Hold material in vertical position. • A reading stand or clipboard may help to keep material flat and steady. • Practice for 5 to 10 minutes several times a day in the beginning. • Asthenopia may be experienced

23. Stand magnifier • Reading portion may be used for patient who have bifocals. • Place the base of the stand flat against the reading material. • The print is automatically in focus when the stand magnifier rests on the page. • Moving closer to material will allow the px to see a larger area at one time.

24. View from the centre • The px must move the stand magnifier across the page as he/she reads.

25. The importance of training and education • To ascertain how the patient is adjusting to the use of the device/s. • To establish if the patient has any problems with the use and care of the device/s • The patient must demonstrate the use of the device/s and comment on the his/her vision with the device/s.

26. General guidelines for the training • Motivation • Explanation • Demonstration • Practice • Transfer

27. Motivation • The patient must be well motivated to perform certain visual skills • He/she must understand the purpose of the skill • And how it relates to the desired task.

28. Explanation • How does the device work? • At what distance does the device have to be use.

29. Demonstration • Clearly demonstrate how the device must be used by the patient. • Make sure that the patient understands and stay motivated by choosing the relevant material.

30. Practice • This is preferably done under the supervision of the examiner or the. • The patient must be given clear instructions and guided accordingly.

31. Transfer • The skill learned in the clinic setting must be transferred to the patients home or at work situation. • Practice must therefore takes place in the “real life" setting.

32. training session requirements • Comfortable room • Good central lighting • Additional desk lighting for near work • Variety of print • Different charts • Reading exercises • Reading stands

33. Typoscope or bar readers • Other necessary devices- • Material must resemble the desired task set by the patient. • E.g. if the desired task is to sew, use sewing material, not reading cards.

34. Follow-up visits • First visit is after a week or two weeks. • After three months • After six months

35. Summary slide • Case history • VA measurements • Refraction • Magnification/ power calculation • Special considerations • Device Prescription • Training with a device • Loan • Follow up visits