Optical aids for low vision patients : is it all we need to do ?

Non optical management of patient with Low vision

1. Moderator:                                                                Presenters : Niraj Dev Joshi                                                         Ashi Lakher                                                                                   Manila Maharjan                                                                                                                                                                                                                                    Optical Aids for Low Vision patients :  Is it all we need to do ?

2. Presentation layout: Introduction to low vision Optical Low vision aids  Non optical low vision aids Psychosocial implication of low vision Optomeric low vision services Summary References

3. Introduction to  Low Vision: " A person with low vision is one who has impairment of visual functioning even after treatment or standard refractive correction and has a visual acuity of less than 6/18 to light perception, or a visual field less than 10 degrees from the point of fixation, but who uses, or is potentially able to use, vision for the planning and execution of a task."                                                       - WHO Definition of Low Vision  Functionally, low vision is a level of vision that prevents a person from carrying out their day-to-day activities

4. Optical Devices in Low vision: These devices can provide greatly increased magnification powers along with higher-quality optics. Low vision optical devices are task-specific.                                                                                                    Two types: Near low vision aids Distance low vision aids

5. Near low vision aids: Distance low vision aids:  Spectacle reading glass Handheld telescope  Handheld magnifier Spectacle mounted telescope Stand magnifier Projection magnification Telemicroscope

6. Is it all we need to do Non optical devices Optical Magnification Sequential treatment plan of low vision patient Patient education Therapeutic Activity Environmental modification Computer technology

7. Non optical low vision aids:

8. It plays an important role in successful use of many low vision optical devices. It uses relative size ,illumination ,position ,contrast ,colour or other sensory input for their effect. They alter environmental perception through:   BBB – Bigger, brighter and blacker, or   CCC – Closer, color , and contrast.

9. Types of non-optical aids : 1.Relative size and larger assistive devices 2.Glare, lighting control devices and contrast 3.Posture and comfort maintenance devices 4.Handwriting and written communication devices 5.Medical management devices 6.Orientation and mobility management techniques and devices 7.Sensory substitution devices

10. 1.Relative size and larger assistive devices: The use of relative size involves the concept of using a larger size object. The type of magnification involved is relative size magnification. Larger size object causes enlarging of the retinal image so that the image of fixed object stimulates larger number of photoreceptors. No use of lenses for magnification as well as no change of working distance.

11. Larger print size: Largest category under relative size devices. Large print books and reading materials enlarged up to 18 print sizes are readable by most of the low vision patients. In addition to large print ,attention must be given to contrast. Light print on dark background may be more readable than customary dark print on a white background.

12. Large Print - Magnification Correlated Font Size                   1X 10 pt             2X 16 pt         3X 26 pt     4X 36 pt    5X 44 pt 11X 92 pt Readers digest large print magazine for easier reading

13. Advantages Easy acceptance by poor or reduced contrast patient. Large prints along with low powered optical devices provides proper magnification. Disadvantages Limited magnification is the major disadvantage. Seldom available Takes additional space to print making it thicker and heavier.

14. Other relative size devices: Large telephone dials Enlarged print clocks and watches Calculators Large prints check Large bead pins for sewing  ,etc.

15. 2.Glare, contrast ,and lighting control devices Glare: Glare may impact patient's functional vision by reducing contrast. Occurs in patient with PSCC, albinism, optic atrophy ,glaucoma, Retinitis pigmentosa, etc. Reduce glare from windows and lights , as much as possible (using shades, curtains, etc.)

16. Cover shiny tabletops  with light-absorbing materials. Also, avoid shiny surfaces on tables , desks, blackboards, laminated or glass covered surfaces. Yellow filters  or acetate can be placed over reading material. When choosing paper,  avoid a glossy finish  as it can lessen legibility and can produce glare.

17. Illumination : Incandescent lamp ,fluorescent lamp ,neodymium bulb, halogen lamp ,etc can be used as light source. Counselling the patient for the proper positioning of light source and wattage of the light source is important. The bulb should have an air  cooled shield surrounding to protect the patient from the heat of bulb and to eliminate any possible glare.

18. Light source should be directed over the shoulder of better seeing eyes and held close to reading material to get maximum illumination.

19. Filters: It is used to enhance the visual performance . Filters will attenuate excessive light to comfort level and reduce both discomfort and disability glare. Material, colour, transmission ,density , photo chromaticity, polarization and coating can impact unique properties of filters .

20. NOIR medical technologies : They are plastic fibres designed to absorb the near UV and near infrared region of spectrum. Prescribed for patient with photophobia and glare.

21. Corning photochromic filters(CPF) : They cut off spectral wavelength below which virtually all light is absorbed and above which substantial transmission occur. To protect eyes with progressive retinal degeneration CPF 550 nm filter- Designed for retinitis pigmentosa patient .It reduce scotopic transmittance and allow photopic transmittance CPF 450 – It reduces glare of fluorescent light, CPF 550XD- Application in patient with aniridia , achromatopsia Glare cutter ( 390-410nm)- cuts 100%UVB, 99% UVA

22. Younger protective lenses: It works by blocking shorter wavelength thus reducing scatter encountered within the ocular media. Polarization: Polarization may be included with filter to improve the glare reduction.

23. Antireflection coating: Single layer or multiple layer Higher the refractive index greater need of antireflective coatings Materials used are metallic chlorides and fluorides, metals such as lithium, sodium and alkaline earth metals like magnesium. Mirror coating : It reduces the transmission and act as filters. It enhances the performance of the absorption by adding the property of reflection.

24. Pinholes and stenopaic slit Pinhole uses the principle to reduce the size of blur circle on the retina. Pinhole glasses or stenopeic glasses has many small holes in their opaque metal or plastic surface. Multiple pinhole glasses may be helpful to patient with reduced vision secondary to anterior segment involvement like-media opacity, corneal involvement or possibly cataract. But when vision impairment is due to macular pathology it may not work well because may decrease illuminance.

25. The stenopaic slit (horizontally placed in sunglasses)were used to control illumination but now their use is limited.

26. Typoscopes A typoscope is an inexpensive piece of durable black plastic with   cutout opening that can help focus on the line you are reading. Advantages They can help follow, or track, along the reading line They can help draw attention where to look on the page. They provide excellent contrast with the reading page. Can also be used as a signature guide.

27. Contrast: Adjustment of appropriate color and contrast around the working environment must be considered. -Wall and ceiling color -Furniture and decorating materials -Color the wall root, railing and staircase -Door and windows knob and handle -Kitchen vase and vessels -Edges of the staircase -Bed sheet, curtain, pillow cover and table cover -Floor color

28. Environmental modification Painted edges of stair case Contrast in kitchen

29. 3.Posture and Comfort Maintenance: Optical device prescription becomes unsuccessful if patient is uncomfortable due to postural demands imposed by prescribed device. Correct posture must be maintained to prevent premature fatigue. Reading material must be tilted at an angle about 45-60 degrees from vertical to improve legibility of reading material.

30. Posture and comfort maintenance devices includes: Reading racks Book stands Lap desks Copy holders Ring stand Head bands

31. Reading racks ,book stands ,copy holders helps to place the material closer to achieve relative distance magnification. Lap desk allows the print to be positioned in place where there is no flat surface like reading in bed. If hand held telescope are prescribed, ring stand or head band may aid for prolonged viewing purpose.

32. 4.Handwriting and written communication devices: These devices helps to make writing tasks easier. Handwriting and written communication device includes: Large typewriters Handwriting and signature guides Bold felt tip pen and special paper

33. Large print typewriters These make writing task easier for patient having hand tremor or arthritis.

34. Handwriting and signature guides These assist in proper placement of handwritten notes and signature. May be signature guides,envelope addressing guides,letter writing guides depending on the task.

35. Bold felt tip pen and special paper Bold felt tip pen with black ink provides better contrast . Wide barrel pens,pens with rubber grip may be helpful in patient with poor grip. White non glossy thick paper with wide spacing is preferred.

36. 5.Medical management non optical device: Medical necessities related task may be: Identifying medications Monitoring blood pressure Monitoring body weight Monitoring blood glucose level Monitoring body temperature Monitoring blood pressure Large output display sphygmomanometer with readout feature.

37. Monitoring blood glucose Glucometer with large display screen or auditory output. Large print syringe , prefilled syringe, preset dosage may be helpful to administer insulin. Monitoring body temperature Large readout thermometer.

38. 6.Orientation and mobility management techniques and devices: It includes: Sighted guide technique Canes Dog guide Electronic travel aids Sighted guide technique A technique in which sighted individual assist a low vision patient with non verbal cues for safe and efficient travel.

39. Canes Canes helps the patient to sense the environment. Long canes ,folding or collapsing canes are useful. Dog guides Dogs serve as companion and helper to patient. Typical breed for dog guides are German shepherd, Golden retriever and Labrador retriever.

40. Electronic travel aids Electronic travel aids provides information that allows determination of size ,range and direction of an object. It includes pathsounder ,wheelchair path finder ,laser canes etc. These emit ultrasonic waves and the reflected waves from object helps in detection of obstacles producing auditory or vibratory output.

41. Mobility also depends on illumination level. Low vision patient may have difficulty in mobility in dim illumination. Devices like WAML(wide angle mobility light)and NVD(night vision devices)aid in mobility in dim illumination.

42. 7.Sensory substitution device: These are used when no optical device is helpful due to poor vision. Hearing ,touch ,taste , smell can be used for sensory substitution. Auditory substitution : sensory input in the form of audio. Talking books Talking products Reader services

43. Talking books It consists of audio recordings on cassettes ,discs , tapes. Reading rate through cassette is 150-175 words/minute. Reader services Personal reader can be helpful. Other reading services include radio reading service, audio reading service for television ,theatrical performance.

44. Talking products Includes talking watches, clocks,telephones , Computers etc. Includes reading machines that uses optical scanner which converts printed characters on page to speech output.

45. Tactile substitution: sensory input in the form of touch. Braille Basic touch Moon Fishburne alphabet Basic touch Texture of surfaces , hardness or softness of objects , temperature of an object perceived through finger tips etc.

46. BRAILLE Braille print consists of raised pattern of dots representing letters or symbols. Braille cell consists of six dots with different orientations. MOON System of raised shapes. Uses large and simplified roman letters. Moon alphabet is made up of nine characters in different positions.

47. Computer technology With the help of modern technology people with vision loss can write documents ,browse internet ,send and receive E-mails etc Screen reading softwares such as Non-visual Desktop Access ,Web Anywhere ,Orca etc are available to help low vision patient.

48. Different mobile apps are also available .Some are: Look Tel: Money identifier KNFB reader app :virtually reads text TapTapSee : Identify objects through Photos Color ID Free: Discovers name of colours around you Be My Eyes:Sighted people helping Low Vision Patient in Real Time Special Braille keyboards are available to take notes. Braille systems are available to translate standard text to Braille Format or vice versa.

49. Psychosocial support Impact of visual impairment also includes psychosocial issues of patient. Psychosocial issues may be shock ,anger ,depression , inferiority complex , rejection etc. Psychological support can be provided through: Effective communication Family as a resource Resources

50. Effective communication Active listening and acknowledging the feelings shared by the patient is a key to effective communication. A practitioner must focus on problem areas experienced by the patient in current lifestyle. Family as a resource Family can impact the outcome of low vision services and serve as a resource and support system. It is important to observe family interaction and encourage the family members to be a part of rehabilitation process.

51. Resource Practitioner should be knowledgeable about community resource addressing psychological needs of patient. Support groups may be helpful .Support group is a group of individual with similar psychological issues bonded by common experiences. Various organizations like National Organization for Albinism and Hypopigmentation , Foundation Fighting Blindness operate to address the psychosocial need of visually impaired people.

52. Case report: low vision management in a case of Stargardt’s Disease A 26 year old female referred to low vision clinic from retina clinic of BPKLCOS with provisional diagnosis of Stargard’s disease. She had slow and progressive diminution of vision in both eyes since 8 years. She had no history of wearing glasses and low vision examination. Her chief visual problems were: Blurring of Distance vision Difficulty in identifying small prints Difficulty in bright day light

53. Low vision examination Visual acuity Distance VA: OD=0.50logMAR, OS=0.56logMAR Near VA: at 33cm Refraction Net retinoscopy: OU=+1.00/-0.50 × Binocularity assessment EOM was full ranged and patient was orthophoric . Visual Field: VF was WNL with confrontation test. Contrast Sensitivity Test: OU=1.6 log units with Pelli -Robson Chart Trial for distance and near vision devices along with absorptive lenses  

54. Rehabilitation plan Spectacle correction with clip on telescope(1.5×) for distance which improved visual acuity to 0.20logMAR. Bar magnifier (1.5×) for near which improved visual acuity to . 54% yellow filter on spectacles which improved contrast and reduce glare . Table lamp with fluorescent direct light for aiding near vision. In the particular case above, optical aids provide clarity to vision while non optical aids provide comfortness to vision. Thus, both are integral part of low vision management.  

55. Case report II:low vision management in a 5-year old due to Retinopathy of Prematurity for life quality improvement A 5 year old boy referred to low vision clinic from Pediatric Ophthalmology Division with provisional diagnosis of Retinopathy of Prematurity along with LE-Aphakia and RE-Band keratopathy. ROP was more severe in RE(stage 5)than LE.Prophylactic treatment (Anti VEGF injection and vitrectomy) was provided in LE causing the eye to develop complicated cataract and underwent cataract surgery causing aphakia. He was born at 28 weeks of gestation and had received oxygen therapy at neonatal ICU. His birth weight was 1600 gram.

56. He has a history of spectacle wear(+12.00D) after cataract surgery. He was accompanied by his mother during low vision evaluation. His chief visual problem was difficulty in near vision task like learning alphabets and numbers. He had no history of colour perception problem and bumping into objects.

57. Low vision assessment Visual acuity(LEA acuity chart) Unaided Distance VA: OD=light perception, OS=1/25 Aided Distance VA:OD=light perception, OS=2/25 Unaided near VA:10M at 30cm. Refraction Net retinoscopy:OD = not able to assess(NCV) OS=+14.00D LE distance vision improved to 3/40 and near vision improved to 4M at 13cm with +3.00D.

58. Contrast sensitivity testing:CS 80 (1.25%) at 3m with Heiding Heidi chart. Visual field testing : WNL in LE with confrontation test Trial for Distance and Near vision Devices was done. Trial for non optical devices providing letter magnification , lightning , contrast, support for writing and reading was done.

59. Rehabilitation plan +14.00D spectacles for Distance +3.00D glasses for near Anti reflective coatings in spectacles can be considered. Table lamp with direct non glare illumination may be helpful at near. Software for screen magnification , audio books etc maybe helpful. Apart from optical and non optical aids ,referral to concerned rehabilitation specialist must also be recommended to learn vision aided skills required for performing daily life activities independently.

60. Optometric low vision services A functional and social history Screening for depression and behavioural changes Assessment of visual status Patient education Exploration and education of low vision aids ,low vision strategies and adaptation

61. Referral to different rehabilitation specialists such as: Occupational and physical therapist Orientation and mobility specialists Social workers Vocational rehabilitation counsellors

62. Take home message A successful low vision practitioner is the one who gives attention to whole person not just the physical aspect of vision loss.

63. References CET Articles INTERNET