low vision intro and definitions, this PPT comprises, basic definitions and concepts of Low Vision

Introduction to Low Vision: Concepts, Definition, Blindness, Who Definition, Contrast Sensitivity, LogMAR chart

1. Low vision Ms Kalsoom Rani Low Vision Rehabilitation Specialist Sr Coordinator/Lecturer OD TUF

2. Overview What is low vision Global prevalence Role of Optometrist Low Vision Management Aim of low Vision Management

3. What is Low Vision? Low vision is a significant reduction of visual function that cannot be fully corrected by ordinary glasses, contact lenses, medical treatment and/or surgery.

4. Who defines low vision as A person with Low vision is one who has Impairment of the visual functioning even after treatment and/or refractive correction, and has a visual acuity of less than 6/18 to light perception, or a visual field of less then 10 degrees from the point of fixation, but who uses, or is potentially able to use, vision for the planning and performance of a task.

5. Distribution of L.V and Blindness by age group 58% (22 million) of the global blind population are aged at least 60

6. WHO (2012) prevalence of blindness, low vision, visual impairment

7. COMPARING VISION IN NORMAL SUBJECTS Vs VISION IN PATIENTS WITH LOW VISION

8. Normal Vision

9. Low Vision (macular deg/optic Atrophy)

10. Low Vision ( D.R)

11. Low Vision ( R.P/ Glaucoma)

12. Impact of Low Vision The impact of low vision on a person's quality of life can be devastating, People with low vision have difficulty with everyday activities, such as reading the newspaper, recognizing familiar faces, self grooming, orientation and mobility and working at their jobs.

13. Role of Optometrist Convert the useless dependent person of society into useful independent working person of society low vision is one of the specialized branch of Optometry Optometrist required special Training for the use of devices and gadgets and Counseling and Rehabilitation

14. Responsibilities of Low Vision Specialist Proper Assessment Identification of task Management Training Coordination and Referral

15. Assessment Functional vision Visual acuity Color vision Contrast Visual field

16. Management Distance vision Telescopes : With Specialized Training

17. Near vision: Magnifiers

18. Electronic

19. Software's

20. a. Magic Software;(low vision) Magnifying screen Up to 10X. Mouse & Cursor Enhancement. Change of Color& Adjustable Size.

21. Visual Enhancements Exercise : Amblyopic therapy E-centric Exc. Convergence Exc. Bright object Exc.

22. Self Grooming Training:

23. Orientation & Mobility Training:

24. Vocational skills

25. Job & employment of visually impaired persons Coordination with different organization Motivate them to create job vacancies

26. Psychological Counseling

27. Aim of low vision Management Low vision persons are neither blind nor normal they are miss fit in blind and normal Through proper low vision management they can successfully move in normal streamline performing their jobs studies with normal individuals Inclusion of visual impaired person into Normal stream line

28. Thank you

29. Blindness ,Causes, Types Prevalence Ms Kalsoom Rani SR Coordinator/Lecturer OD Optometrist & Orthoptics LOW Vision Rehabilitation Specialist .

30. Learning out come Causes of blindness Global distribution Prevalence Pakistan situation Definition of blindness and visual impairment used

31. Global Initiative to Eliminate Avoidable Blindness by the Year 2020 World Health Organisation- IAPB

32. Present situation Present estimation: 45 million people blind + 135 million visually disabled Low Vision Blind < 6/18 - 3/60 <0.3 - 0.05 < 3/60 <0.05 Best corrected VA International classification ignores the burden of uncorrected refractive error

33. World Prevalence of Blindness 0.4 - 0.6 0.6 - 1 > 1% < 0.4% Prevalences:

34. Prevalence of Blindness 90%+ live in underprivileged communities

35. The ‘blindness’ rate in many developing countries, especially in Africa, is 7 times higher, at 1.4%, than in developed countries

36. Gender is another major issue

37. Global Distribution of Blindness by Cause Cataract 42 % Trachoma 15 % Glaucoma 14% Oncho. 1 % Other 28 % Macular degeneration Diabetic retinopathy + Refractive errors (uncorrected)

38. Present situation 80% of blindness is avoidable preventable or curable

39. Leading Causes of Preventable Blindness: Cataract Trachoma Onchoceriasis Childhood Blindness Refractive Error & Low Vision

40. VISION 2020 Vision 2020 will strive to make refractive services and corrective spectacles affordable and available to the majority of the population through primary health care facilities, vision screening in schools and low-cost production of spectacles. Similar strategies will be adopted to provide low vision services.

41. Global estimates Magnitude of refractive errors not reliably known Large global variation in prevalence (by age, gender, and race) Estimated: 2.3 billion people have refractive error 1.8 billion have access to refractive services 500 million do not have access to services

42. Sth Africa 1.0% RE:10% Cook, 1992 (n=268) China 4.4% Due to RE:10% Shaozhen Li, 1999 (n=5342) Australia 0.15% Due to RE:25% Taylor, 1997 (n=3268) India 2.5% Due to RE:9.6% Dandona, 1998 (n=2522) Saudi Arabia 0.7% RE: 5.3% Al Faran, 1993 (n=2882) 10%+ of World Blindness Blindness Due To Uncorrected Refractive Errors (<3/60)

43. Difficulties with Current Data Non-uniform definitions across studies Non-representative study populations (convenience rather than population-based) Dissimilar demographics of study population (age and sex) Refraction procedures are different (with/without cycloplegia etc) Negrel, Ellwein, 2001

44. Uncorrected refractive error is the major cause of: blindness following mass cataract surgery using standard power IOL

45. Myopia with Autorefraction: Country Comparison

46. Low Vision 35m people worldwide have irreversible vision loss and are in need of low vision care. *WHO Global Initiative: Vision 2020, Feb 1999 VISION 2020 will enable access to visual devices & low vision care at affordable cost Treatment: Low vision care & vision correction

47. components Disease control through service delivery Human resource development Infrastructure and technology

48. Collaborations has created valuable and effective collaborations of organisations WCO until 2002 was not a part of the International Agency for the Prevention of Blindness

49. Optometry a late entrant It is only recently that uncorrected refractive error and even more recently low vision has achieved prominence Landmark population-based studies in adults, children and in post-cataract patients.

50. Prevalence According to WHO: It is estimated that over seven million people become blind every year. 75% of blindness is avoidable 80% of visual impairment is avoidable 63% of those with low vision and 82% of blind people are over 50 years of age Of the six WHO regions, South East Asia and Western Pacific account for 73% of moderate to severe visual impairment and 58% of blindness.   http://www.kernersvillerotary.org/images2009/052107BlindSchool7.JPG http://www.who.int/topics/blindness/en/

51. About 285 million people are visually impaired world wide, 39.8 million of them are blind Most of the people with visual impairment are older, and females are more at risk at every age, in every part of the world. 90% of people with visual impairments live in developing countries

52. Cataract remains the leading cause of blindness globally, except in the most developed countries. Cataract surgery and correction of refractive errors are among the most cost-effective health interventions. l

53. Key Facts 1.4 million children under age 15 are blind. Correction of refractive errors could give normal vision to more than 12 million children (ages 5-15). The number of people blinded by infectious diseases has been greatly reduced. Age related impairment is increasing. Blinding trachoma affects 40 million people today, compared to 360 million in 1985.

54. Pakistan 2007 A sample of 16 507 adults (95.5% of those enumerated) was examined. Cataract was the most common cause of blindness (51.5%; defined as <3/60 in the better eye on presentation) corneal opacity (11.8%), uncorrected aphakia (8.6%) and glaucoma (7.1%). Posterior capsular opacification accounted for 3.6% of blindness.

55. Among the moderately visually impaired (<6/18 to > or =6/60), refractive error was the most common cause (43%), followed by cataract (42%). Refractive error as a cause of severe visual impairment/blindness was significantly higher in rural than in urban (odds ratio (OR) 3.5, 95% CI 1.1 to 11.7). Significant provincial differences were also identified. Overall we estimate that 85.5% of causes were avoidable and that 904 000 adults in Pakistan have cataract (<6/60) requiring surgical intervention.

56. 2011 Province Estimated number of blind individuals Punjab 769,000 Sindh 200,000 NWFP 114,000 Baluchistan 52,000 Total 1,140,000

57. Avoidable Causes Cataract 51.5% Corneal opacity 11.8% Uncorrected aphakia 8.6% Glaucoma 7.1% Posterior capsular opacification 3.6%

58. Refractive error 2.7% Diabetic retinopathy 0.2% Total avoidable causes 85.4% Unavoidable Causes Phthisis/absent globe 2.7% Macular degeneration 2.1% Optic atrophy 0.9% Amblyopia 0.5% Other 8.4% Total unavoidable causes 14.6%

59. DEFINITION A key issue in any discussion of blindness is its definition. The elements of this definition that need attention are level of distance visual acuity, presenting or best-corrected visual acuity visual field constriction. In the United States, legal blindness is defined as distance visual acuity ≤20/200. Tasman, Duane's Ophthalmology, Lippincott Williams & Wilkins ( 2005)

60. Definitions ( ICD-10): Low Vision: V isual acuity of less than 6/18 but equal to better than 3/60 or corresponding visual field loss to less than 20 degrees in the better eye with the best possible correction Blindness: Visual acuity <3/60 or a corresponding visual field loss to less than 10 degrees in the better eye with the best possible correction. Visual Impairment Includes low vision as well blindness http://www.who.int/bulletin/volumes/82/11/en/844.pdf

61. DEFINITION This definition, based on best-corrected visual acuity, excludes the large number of people worldwide who are visually impaired due to uncorrected refractive error. Visual field constriction, independent of visual acuity, causes functional impairment. The inclusion of visual field criteria in the definition of blindness is recommended by the ICD-10 Visual fields are difficult to assess and many studies have not included visual field constriction in estimates of the prevalence of visual impairment.

62. VISUAL FUNCTION In addition, visual function is comprised of many other components. These include visual field color perception stereo acuity glare recovery dark adaptation contrast sensitivity function. These qualities of vision are not commonly assessed in population based visual impairment prevalence studies

63. Classification: international classification of disease ,9 th revision clinical modification (ICD-9-CM) Moderate visual impairment : B/C 20/60 to 20/160 6/18 to 6/48. Severe visual impairment : B/C 20/160 to 20/200 ,6/18 to 6/120 Profound visual impairment : B/C 20/ 400 to 20/10,00 ,6/120 to 6/300. Near total vision loss :B/C 20/1250 or less , 6/300 to 6/375. Total blindness :NPL

64. Proposed revision of categories of visual impairment Category Worse than Equal or better than Moderate or visual impairment 3/10 (0,3) 1/10 (0,1) 20/70 6/60 1/10 (0.1) 20/200 Severe Visual Impairment 6/60 1/10 (0.1) 20/200 3/60 1/20(0.05) 20/400 Blindness 3 3/60 1/20(0.05) 20/400 1/60 1/50(0.02) 5/300 (20/1200) Blindness 4 1/60 1/50(0.02) 5/300 (20/1200) Light perception Blindness 5 No light perception http://www.who.int/blindness/Change%20the%20Definition%20of%20Blindness.pdf

65. n  North America  and most of  Europe , legal blindness is defined as  visual acuity  (vision) of 20/200 (6/60) or less in the better eye with best correction possible people with average acuity who nonetheless have a  visual field  of less than 20  degrees  (the norm being 180 degrees) are also classified as being legally blind.

66. WHO Blindness  is defined as visual acuity of less than 20/400 (6/120), or corresponding visual field loss to less than 10 degrees, in the better eye with best possible correction.

67. Avoidable blindness Treatable blindness Preventable blindness Un preventable blindness Unavoidable blindness Not treatable blindness