Amrit Pokharel
Dystrophy??   A hereditary, symmetrical, congenital or later    appearing, slowly progressive affection,    presenting sl...
Dystrophy??   It was suggested that conditions secondary to    systemic factors should not be considered    dystrophies, ...
Retinal Dystrophies   Generalised photoreceptor dystrophies     Typical  retinitis pigmentosa     Atypical retinitis pi...
Retinal Dystrophies   Generalised photoreceptor dystrophies     Familial             benign fleck retina     Pigmentary...
Retinal Dystrophies   Macular Dystrophies     Juvenile Best macular dystrophy     Multifocal Vitelliform lesions withou...
Retinal Dystrophies   Macular Dystrophies     Benign  concentric annular macular dystrophy     Central areolar choroida...
Goals   Identify patients with visual impairment(s) who    might benefit from low vision care and    rehabilitation   Ev...
Goals   Maintain and improve the quality of eye and    vision care rendered to visually impaired    patients   Inform an...
Goals   Increase access for the evaluation and    rehabilitative care of individuals with visual    impairment(s), thereb...
   Vision rehabilitation   As defined by the American Optometric    Association   the process of treatment and educatio...
   and treatment including, but not limited to, the    prescription of optical,   non-optical, electronic and/or other t...
Quantifiers of Visual Impairment   The ICD 10-ICIDH has employed the following    quantifiers:     Visual   Acuity     ...
Quantifiers of Visual Impairment   The approach is to use functional terms to    classify the type of Visual Field defect...
Quantifiers of Visual Impairment   …the patient may encounter:     Novisual field defect, but a loss of resolution or   ...
   For rehabilitation work, must know thing:     Visualfield defect    loss of contrast and     resolution     Central ...
   For the Guideline here on how to rehabilitate    the patients with retinal dystrophy,   Low vision instruction, low v...
CARE PROCESS   Diagnosis of Low Vision     PatientHistory     Ocular Examination       Visual Acuity            Monit...
CARE PROCESS   Diagnosis of Low Vision     PatientHistory     Ocular Examination       Refraction            Use of J...
CARE PROCESS   Diagnosis of Low Vision     PatientHistory     Ocular Examination       Ocular   motility and Binocular...
CARE PROCESS   Diagnosis of Low Vision     PatientHistory     Ocular Examination       Ocular   motility and Binocular...
CARE PROCESS   Diagnosis of Low Vision     PatientHistory     Ocular Examination       Ocular   motility and Binocular...
CARE PROCESS   Diagnosis of Low Vision     PatientHistory     Ocular Examination       Visual   Field Assessment      ...
CARE PROCESS   Diagnosis of Low Vision     PatientHistory     Ocular Examination       Ocular   Health Assessment     ...
CARE PROCESS   Diagnosis of Low Vision     PatientHistory     Ocular Examination     Supplemental Testing       Contr...
CARE PROCESSManagement (Low visionrehabilitation)
Rehabilitation   The goals discussed earlier are met by;     Improving   distance, intermediate, or near vision     Imp...
Rehabilitation   The goals discussed earlier are met by;     Improving   the ability to travel independently     Improv...
How to start??   An optometrist should individualize    the management plan for each    patient while planning a course o...
How to start??   An optometrist should CONSIDER    the following:     Degree   of VI     Underlying    cause( here reti...
How to start??   An optometrist should CONSIDER    the following:     Overall   health status of the patient     Patien...
How to start??   An optometrist should CONSIDER    the following:     Patient‟s   expectations and motivations     Pati...
Rehabilitation process   Use of devices:     Optical            Devices     Non-Optical Devices       RGPHOMeS
Looking at the statistics… 40 35 30 25 20   40 15 10  5        10   10   10                       10                      ...
`Presenting complaint                Possible rehabilitation optionsDifficulty in reading               Refraction, lighti...
`Presenting complaint                    Possible rehabilitation optionsDifficulty in using computer screens    Text enlar...
Eccentric viewing
 Eccentric Viewing Eccentric viewing refers to the technique  of   observing a scene with the peripheral    retina, by ...
 Eccentric Viewing Due to the lower density of photoreceptors  and greater number of photoreceptors per  ganglion cell i...
Retinitis PigmentosaUsher SyndromeHallgren‟s SyndromeRefsum‟s syndrome
   Prognosis:        worst prognosis severe Vision loss by 4th     XL-     decade     ARor sporadic cases-favourable wi...
 ERG   in RP   Decreased in fERG   Early pERG may be normal,Later gets abnormal   Amplitude  reduction in the   periph...
CHARACTERISTICS OFDISEASES Dark Line in Retina Decreased Night Vision Loss of Peripheral/Central Vision Decrease in Vi...
Functional Implications   Peripheral vision lost   Limited visual field   Limited mobility   Debilitating glare   Ext...
Rehabilitation   Wearing glasses   Low vision devices   Magnification and    illumination of    objects
Rehabilitation   Field enhancers are    employed since    visual field is    markedly    constricted.
Rehabilitation   So how is peripheral VF defect    management launched?
Rehabilitation   Consider the goals as given by the    AOA and work under the following    five areas:     Maximized   V...
Rehabilitation   Consider the goals as given by the    AOO and work under the following    five areas:    Maximized VA  ...
Rehabilitation   Consider the goals as given by the    AOO and work under the following    five areas:    Maximized VA  ...
Rehabilitation   Consider the goals as given by the    AOO and work under the following    five areas:    Maximized VA  ...
Rehabilitation   Consider the goals as given by the    AOO and work under the following    five areas:    Maximized VA  ...
Rehabilitation   Consider the goals as given by the    AOO and work under the following    five areas:    Maximized VA  ...
Rehabilitation   Consider the goals as given by the    AOO and work under the following    five areas:    Glare and phot...
Rehabilitation   Consider the goals as given by the    AOO and work under the following    five areas:    Glare and phot...
Rehabilitation   Consider the goals as given by the    AOO and work under the following    five areas:    Glare and phot...
Rehabilitation   Consider the goals as given by the    AOO and work under the following    five areas:    Glare and phot...
Rehabilitation   Consider the goals as given by the    AOO and work under the following    five areas:    Glare and phot...
Glare and Contrast
Rehabilitation   Consider the goals as given by the    AOO and work under the following    five areas:    Glare and phot...
Rehabilitation   Consider the goals as given by the    AOO and work under the following    five areas:    Glare and phot...
Rehabilitation
Adequate light ( natural /  lamp) for daily tasks
Rehabilitation   Consider the goals as given by the    AOO and work under the following    five areas:    Glare and phot...
Rehabilitation   Consider the goals as given by the    AOO and work under the following    five areas:    Magnification ...
Rehabilitation   Consider the goals as given by the    AOO and work under the following    five areas:    Magnification ...
Stand magnifiers
Hand Held Magnifiers
Rehabilitation   Consider the goals as given by the    AOO and work under the following    five areas:    Visual Field  ...
Cone shaped VF in RP
Rehabilitation   Consider the goals as given by the    AOO and work under the following    five areas:    Visual Field  ...
Prism        E.g..   Fresnel prism
Interpretation   When peripheral vision loss is severe    (leaving central visual fields of less than    20°), mobility c...
Interpretation   Fresnel prisms may not cause the same    central visual field degradation and have    added advantages o...
Interpretation   We constantly scan our environment using low    spatial-frequency visual channels as we also    intermit...
Interpretation   In the presence of tunnel vision, prisms project    peripheral fields information otherwise    unavailab...
Mirrors
Minus lens
Reverse Telescope system
Amorphic lens
Also contrast sensitivity…
Also contrast sensitivity…         Contrast in Kitchen
Environmental   Painted edges of Staircasemodification
O and M management
O and M management
Sensory- substitution devices
Other Non-optical Devices
Progressive Cone dystrophyInheritance    Sporadic, AD or XLPresentation   2nd -4th decade with               central Vf , ...
   dfnjks
Stargardt macular dystrophyInheritance     Sporadic, ARPresentation    1st -2nd decade with                central VF ,   ...
Characteristics…
Characteristics…    Poor    Colour    Vision
Tests to be carried out…
Management   Few guidelines,     When scotoma is located right to the     macula, reading becomes difficult as the previ...
Management   Refraction   Magnification   Non-optical devices   Lighting and glare control   Eccentric Viewing   Pri...
Management   Eccentric Viewing     To   extrafoveate an object of regard
Management …EV   Discussion:     Besides reducing reading speed, the central     scotoma interferes with other visual fu...
Management …EV   Discussion:     After EV training, reading speed doubled with little      to no improvement in Visual A...
Management   Prism Therapy
Management   Text Enhancement…
Management…TextEnhancement   Conclusion     Boosting   the contrast increases the perceptibility      of letters and the...
Psychological/Psychosocialproblems in Retinal Dystrophy   Fear of growing blind   Fear of ostracism   Impaired social l...
Refer                                                  TrainTreat                    Low Vision Service   Eye Care        ...
References:  Tasca Jennifer, Edward A. Deglin. Chapter  SIX „Common Disorders Encountered in Low  Vision‟ in “ESSENTIALS ...
References:   Ferraro, J. and Jose, R. T. (1983). Training    programs for individuals with restricted    fields. In R.T....
References:   Ajit Kumar Thakur, Purushottam    Joshi, Himal Kandel, Subash    Bhatta.Profile of low vision clinics in   ...
References:   Jae Hoon Jeong, Nam Ju Moon. A Study    of Eccentric Viewing for Low Vision    Rehabilitation. Korean J Oph...
References:   William H. Ridder III, John B.    Slegfried.Chapter 16 „Clinical    Electrophysiology‟ in Borish‟s Clinical...
AND YOU THINK YOU ARE HAVING A BAD DAY AT WORK !!Although this looks like a picture taken from a Hollywood movie, it is in...
Low vision rehabilitation in patients with retinal dystrophy
Low vision rehabilitation in patients with retinal dystrophy
Low vision rehabilitation in patients with retinal dystrophy
Low vision rehabilitation in patients with retinal dystrophy
Low vision rehabilitation in patients with retinal dystrophy
Low vision rehabilitation in patients with retinal dystrophy
Low vision rehabilitation in patients with retinal dystrophy
Low vision rehabilitation in patients with retinal dystrophy
Low vision rehabilitation in patients with retinal dystrophy
Low vision rehabilitation in patients with retinal dystrophy
Low vision rehabilitation in patients with retinal dystrophy
Low vision rehabilitation in patients with retinal dystrophy
Low vision rehabilitation in patients with retinal dystrophy
Low vision rehabilitation in patients with retinal dystrophy
Low vision rehabilitation in patients with retinal dystrophy
Low vision rehabilitation in patients with retinal dystrophy
Low vision rehabilitation in patients with retinal dystrophy
Low vision rehabilitation in patients with retinal dystrophy
Low vision rehabilitation in patients with retinal dystrophy
Low vision rehabilitation in patients with retinal dystrophy
Low vision rehabilitation in patients with retinal dystrophy
Low vision rehabilitation in patients with retinal dystrophy
Low vision rehabilitation in patients with retinal dystrophy
Low vision rehabilitation in patients with retinal dystrophy
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Low vision rehabilitation in patients with retinal dystrophy

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The presentation I have made and uploaded provides you with an in-depth insight into the rehabilitation of patients with retinal dystrophy on the part of LOW VSION. It also details the features the patients present with and specific tests that are launched.
The author does not assume responsibility or legal liability for any errors in the text or for the misuse or misapplication of material in this work.
No copyright infringement, or plagiarism intended.
Amrit Pokharel

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Transcript of "Low vision rehabilitation in patients with retinal dystrophy"

  1. 1. Amrit Pokharel
  2. 2. Dystrophy?? A hereditary, symmetrical, congenital or later appearing, slowly progressive affection, presenting slight intrafamilial variation, and of unknown etiology.
  3. 3. Dystrophy?? It was suggested that conditions secondary to systemic factors should not be considered dystrophies, but the authors find it somewhat artificial to exclude entities with systemic manifestations from the definition. Retinitis Pigmentosa has been found to be associated with systemic conditions that are inherited and is called one of the retinal dystrophies
  4. 4. Retinal Dystrophies Generalised photoreceptor dystrophies  Typical retinitis pigmentosa  Atypical retinitis pigmentosa  Progressive cone atrophy  Leber Congenital Amaurosis  Stargardts disease and Fundus flavimaculatus  Bietti corneoretinal crystalline dystrophy  Alport syndrome
  5. 5. Retinal Dystrophies Generalised photoreceptor dystrophies  Familial benign fleck retina  Pigmentary paravenous chorioretinal atrophy  Congenital stationary night blindness  Congenital monochromatism
  6. 6. Retinal Dystrophies Macular Dystrophies  Juvenile Best macular dystrophy  Multifocal Vitelliform lesions without Best disease  Pattern dystrophy  North Carolina macular dystrophy  Familial dominant drusen  Sorsby pseudoinflammatory dystrophy
  7. 7. Retinal Dystrophies Macular Dystrophies  Benign concentric annular macular dystrophy  Central areolar choroidal dystrophy  Dominant cystoid macular oedema  Sjogrens-Larsson syndrome  Familial internal limiting membrane dystrophy
  8. 8. Goals Identify patients with visual impairment(s) who might benefit from low vision care and rehabilitation Evaluate visual functioning of a compromised visual system effectively Emphasize the need for comprehensive assessment of patients with impaired vision and referral to, and interaction with, other appropriate professionals
  9. 9. Goals Maintain and improve the quality of eye and vision care rendered to visually impaired patients Inform and educate other health care practitioners and the lay public regarding the availability of vision rehabilitation services
  10. 10. Goals Increase access for the evaluation and rehabilitative care of individuals with visual impairment(s), thereby improving their quality of life.
  11. 11.  Vision rehabilitation As defined by the American Optometric Association the process of treatment and education that helps individuals who are visually disabled attain maximum function, a sense of well being, a personally satisfying level of independence,
  12. 12.  and treatment including, but not limited to, the prescription of optical, non-optical, electronic and/or other treatments. The rehabilitation process includes the development of an individual rehabilitation plan specifying clinical therapy and/or instruction in
  13. 13. Quantifiers of Visual Impairment The ICD 10-ICIDH has employed the following quantifiers:  Visual Acuity  Visual Field  Contrast Sensitivity
  14. 14. Quantifiers of Visual Impairment The approach is to use functional terms to classify the type of Visual Field defect. This approach is a useful way to think of problems the patient may encounter:
  15. 15. Quantifiers of Visual Impairment …the patient may encounter:  Novisual field defect, but a loss of resolution or contrast throughout the entire visual field; general haze or glare  Central visual field defect  Peripheral visual field defect
  16. 16.  For rehabilitation work, must know thing:  Visualfield defect loss of contrast and resolution  Central VF defect  Peripheral VF defect
  17. 17.  For the Guideline here on how to rehabilitate the patients with retinal dystrophy, Low vision instruction, low vision training, low vision therapy, vision rehabilitation theapy and vision rehabiliatation training are synonymous
  18. 18. CARE PROCESS Diagnosis of Low Vision  PatientHistory  Ocular Examination  Visual Acuity  Monitor stability or progression of disease  Assess eccentric viewing postures and skills  Assess scanning ability( for patients with restricted field)  Assess patient motivation  Teach basic concepts and skills( ie to eccentrically view) relevant to rehabilitation process
  19. 19. CARE PROCESS Diagnosis of Low Vision  PatientHistory  Ocular Examination  Refraction  Use of JND technique  Radical retinoscopy
  20. 20. CARE PROCESS Diagnosis of Low Vision  PatientHistory  Ocular Examination  Ocular motility and Binocular Vision Assessment  Evaluate for the presence of nystagmus, ocular motility dysfunction( eg poor saccades and pursuits)  Look for strabismus, substandard binocularity, or diplopia
  21. 21. CARE PROCESS Diagnosis of Low Vision  PatientHistory  Ocular Examination  Ocular motility and Binocular Vision Assessment  Gross assessment of ocular alignment( eg Hirschberg estimation)  Sensorimotor testing( Worth four dot test, red lens test)  Amsler grid test, monocularly versus binocularly to determine eye dominance and the possible need for occlusion
  22. 22. CARE PROCESS Diagnosis of Low Vision  PatientHistory  Ocular Examination  Ocular motility and Binocular Vision Assessment  Contrast sensitivity , monocularly versus binocularly to determine eye dominance and the possible need for occlusion  Effect of lenses, prisms, or occlusion on visual functioning
  23. 23. CARE PROCESS Diagnosis of Low Vision  PatientHistory  Ocular Examination  Visual Field Assessment  Central vs Peripheral VF defects  Confrontation VF testing  Amsler or threshold Amsler grid assessment  Automated static perimetry  Tangent screening  Goldmann Bowl perimetry or equivalent kinetic testing
  24. 24. CARE PROCESS Diagnosis of Low Vision  PatientHistory  Ocular Examination  Ocular Health Assessment  External examination( adnexa, lids, conjunctiva, iris, lens, and pupillary response)  Biomicroscopy( lids, lashes, conjunctiva, tear film, cornea, anterior chamber, iris, and lenses)  Tonometry  Central and peripheral fundus examination with dilation unless containdicated Dilation not to be carried out prior to working with lenses
  25. 25. CARE PROCESS Diagnosis of Low Vision  PatientHistory  Ocular Examination  Supplemental Testing  Contrast sensitivity testing  Glare testing  Visually Evoked Potentials (VEP)  Electroretinogram( ERG)  Electrooculogram( EOG)  Colour Vision testing
  26. 26. CARE PROCESSManagement (Low visionrehabilitation)
  27. 27. Rehabilitation The goals discussed earlier are met by;  Improving distance, intermediate, or near vision  Improving print reading ability  Reducing photophobia and/or light-to-dark or dark-to-light adaptation time
  28. 28. Rehabilitation The goals discussed earlier are met by;  Improving the ability to travel independently  Improving the ability to perform activities of daily living  Maintaining independence  Understanding the diagnosed vision condition, prognosis,and implications for visual functions
  29. 29. How to start?? An optometrist should individualize the management plan for each patient while planning a course of therapy.
  30. 30. How to start?? An optometrist should CONSIDER the following:  Degree of VI  Underlying cause( here retinal dystrophy)  Patient‟s age and developmental level
  31. 31. How to start?? An optometrist should CONSIDER the following:  Overall health status of the patient  Patient‟s adjustment to visual loss
  32. 32. How to start?? An optometrist should CONSIDER the following:  Patient‟s expectations and motivations  Patient‟s(cognitive) ability to participate in the rehab  Lens systems and technology available
  33. 33. Rehabilitation process Use of devices:  Optical Devices  Non-Optical Devices  RGPHOMeS
  34. 34. Looking at the statistics… 40 35 30 25 20 40 15 10 5 10 10 10 10 5 5 5 3 2 0
  35. 35. `Presenting complaint Possible rehabilitation optionsDifficulty in reading Refraction, lighting, high reading add spectacles, hand held magnifiers, CCTV, large prints/talking booksDifficulty in recognizing faces Refraction, fixation advice/training, lightningDifficulty in watching TV Refraction, Changing Viewing distance, Fixation advice /training telescopic magnifiersDifficulty in navigation/mobility Orientation and mobility training, Refraction, Telescopic magnifiers (for street signs)
  36. 36. `Presenting complaint Possible rehabilitation optionsDifficulty in using computer screens Text enlargement software, Screen reading software, RefractionDifficulty in kitchen/household tasks Lighting, Contrast advice, Hand magnifiersDifficulty in shopping Hand magnifiers, Portable lightning, Handheld CCTVsDifficulty in hobbies Refraction, Galilean Telescopes, Text(reading, music, gardening, painting) enlargement
  37. 37. Eccentric viewing
  38. 38.  Eccentric Viewing Eccentric viewing refers to the technique of  observing a scene with the peripheral retina, by moving the damaged fovea away from the object of interest
  39. 39.  Eccentric Viewing Due to the lower density of photoreceptors and greater number of photoreceptors per ganglion cell in the peripheral retina,  visual acuity will be far worse as that in the fovea.  This strategy can, however, provide an unobstructed view of the scene
  40. 40. Retinitis PigmentosaUsher SyndromeHallgren‟s SyndromeRefsum‟s syndrome
  41. 41.  Prognosis: worst prognosis severe Vision loss by 4th  XL- decade  ARor sporadic cases-favourable with retention of CF until 5th decade  ADbest prognosis and CF present beyond 5th decade
  42. 42.  ERG in RP  Decreased in fERG  Early pERG may be normal,Later gets abnormal  Amplitude reduction in the periphery that corresponds to VF defect
  43. 43. CHARACTERISTICS OFDISEASES Dark Line in Retina Decreased Night Vision Loss of Peripheral/Central Vision Decrease in Visual Acuity
  44. 44. Functional Implications Peripheral vision lost Limited visual field Limited mobility Debilitating glare Extreme sensitivity of light Eventual Blindness
  45. 45. Rehabilitation Wearing glasses Low vision devices Magnification and illumination of objects
  46. 46. Rehabilitation Field enhancers are employed since visual field is markedly constricted.
  47. 47. Rehabilitation So how is peripheral VF defect management launched?
  48. 48. Rehabilitation Consider the goals as given by the AOA and work under the following five areas:  Maximized VA  Glare and photophobia control  Magnification  Field enhancement techniques  Referrals for additional services
  49. 49. Rehabilitation Consider the goals as given by the AOO and work under the following five areas: Maximized VA Visual Acuity  VA testing at appropriate distance so as not to overwhelm the field with the letter size RP patients have difficulty seeing a larger object at near
  50. 50. Rehabilitation Consider the goals as given by the AOO and work under the following five areas: Maximized VA Visual Acuity Proper illumination( towards a brighter side) depending on other ocular associations, Cataracts, for example
  51. 51. Rehabilitation Consider the goals as given by the AOO and work under the following five areas: Maximized VA Refraction Allow for eccentric viewing(EV) Encourage the EV if the px achieves better VA
  52. 52. Rehabilitation Consider the goals as given by the AOO and work under the following five areas: Maximized VA Binocularity The asymmetric nature of RP makes it difficult for pxs to maintain healthy fusion because of differences in the acuity( > 2 lines)
  53. 53. Rehabilitation Consider the goals as given by the AOO and work under the following five areas: Maximized VA Binocularity Also the frequent association of nystagmus supports the binocularity, for monocularity seems to worsen nystagmus.
  54. 54. Rehabilitation Consider the goals as given by the AOO and work under the following five areas: Glare and photophobia control Glare and photophobic sensitivities ??? Reduced contrast sensitivity, slower responses to dark adaptation and secondary media defects…
  55. 55. Rehabilitation Consider the goals as given by the AOO and work under the following five areas: Glare and photophobia control Glare and photophobic sensitivities ??? The RPE tends to absorb less light hence supports light scattering. Glare interferes with the middle and
  56. 56. Rehabilitation Consider the goals as given by the AOO and work under the following five areas: Glare and photophobia control Use of various lenses like Corning, NoIR. These absorb wavelengths towards blue that are responsible for more
  57. 57. Rehabilitation Consider the goals as given by the AOO and work under the following five areas: Glare and photophobia control Corning Lenses CPF 550(Amber) esp for RP NoIR filters 4% Dark Plum 2% Medium Plum
  58. 58. Rehabilitation Consider the goals as given by the AOO and work under the following five areas: Glare and photophobia control Corning Lenses CPF 550(Amber) esp for RP NoIR filters 65% Yellow 49% Red
  59. 59. Glare and Contrast
  60. 60. Rehabilitation Consider the goals as given by the AOO and work under the following five areas: Glare and photophobia control Peaked caps Tinted screen CCTVs Also use of typoscopes
  61. 61. Rehabilitation Consider the goals as given by the AOO and work under the following five areas: Glare and photophobia control Illumination Incandescent lamps( 75-100)
  62. 62. Rehabilitation
  63. 63. Adequate light ( natural / lamp) for daily tasks
  64. 64. Rehabilitation Consider the goals as given by the AOO and work under the following five areas: Glare and photophobia control Place the lighting source behind the px So as to do away with the possible unwanted glare Place it to the side of the
  65. 65. Rehabilitation Consider the goals as given by the AOO and work under the following five areas: Magnification  In peripheral field defects like in RP, the minimal magnification to be provided coz the stimulation of the peripheral retinal may be of little or no value.
  66. 66. Rehabilitation Consider the goals as given by the AOO and work under the following five areas: Magnification Use of microscopes in later stages Also handheld magnifiers, stand magnifiers
  67. 67. Stand magnifiers
  68. 68. Hand Held Magnifiers
  69. 69. Rehabilitation Consider the goals as given by the AOO and work under the following five areas: Visual Field RP shows a cone shaped visual field. Cone shaped?? The patient will show a geometrically expanded field with increased testing
  70. 70. Cone shaped VF in RP
  71. 71. Rehabilitation Consider the goals as given by the AOO and work under the following five areas: Visual Field Enhancers Prism Minus lens Mirror Reverse Telescope
  72. 72. Prism E.g.. Fresnel prism
  73. 73. Interpretation When peripheral vision loss is severe (leaving central visual fields of less than 20°), mobility can be reduced. Clinical rehabilitation options in dealing with tunnel vision using nonprismatic methods are limited and have had variable success
  74. 74. Interpretation Fresnel prisms may not cause the same central visual field degradation and have added advantages of cosmetic appeal, relative availability, and ease of fitting The rationale for using prisms for field expansion involves increasing scanning effectiveness for patients, resulting in improved peripheral awareness.
  75. 75. Interpretation We constantly scan our environment using low spatial-frequency visual channels as we also intermittently spot and view points of interest in visual fields scanned, using various high spatial-frequency visual channels. Cortical temporal multiplexing processes create visual perception as we know it by using the information obtained from scanning and spotting.
  76. 76. Interpretation In the presence of tunnel vision, prisms project peripheral fields information otherwise unavailable, thereby enhancing the scanning abilities of the eye. Enhanced scanning ability will produce new spotting eye movements and together both visual skills in fact expand peripheral field awareness.
  77. 77. Mirrors
  78. 78. Minus lens
  79. 79. Reverse Telescope system
  80. 80. Amorphic lens
  81. 81. Also contrast sensitivity…
  82. 82. Also contrast sensitivity… Contrast in Kitchen
  83. 83. Environmental Painted edges of Staircasemodification
  84. 84. O and M management
  85. 85. O and M management
  86. 86. Sensory- substitution devices
  87. 87. Other Non-optical Devices
  88. 88. Progressive Cone dystrophyInheritance Sporadic, AD or XLPresentation 2nd -4th decade with central Vf , CV impairmentSigns …ERG Photopic response- abnormalDA Cone segment abnormalCV Deuteran-tritan defectPrognosis Poor with eventual loss of CV to the level of 6/60
  89. 89.  dfnjks
  90. 90. Stargardt macular dystrophyInheritance Sporadic, ARPresentation 1st -2nd decade with central VF , malingering??Signs …ERG Photopic response- abnormalDA Cone segment abnormalCV Red-green defectPrognosis Poor with eventual loss of CV to the level of 6/60
  91. 91. Characteristics…
  92. 92. Characteristics… Poor Colour Vision
  93. 93. Tests to be carried out…
  94. 94. Management Few guidelines,  When scotoma is located right to the macula, reading becomes difficult as the previous word disappears—leading to difficulty in tracking  When scotoma is located left to the macula, reading becomes difficult as a new word is readily invisible owing to a scotoma. So one should use finger or marker to overcome problem
  95. 95. Management Refraction Magnification Non-optical devices Lighting and glare control Eccentric Viewing Prism therapy Text Enhancement
  96. 96. Management Eccentric Viewing  To extrafoveate an object of regard
  97. 97. Management …EV Discussion:  Besides reducing reading speed, the central scotoma interferes with other visual functions including  Space perception  Contrast sensitivity,  Stereopsis  Fixation stability  Contraindicated when some form of foveal function exists
  98. 98. Management …EV Discussion:  After EV training, reading speed doubled with little to no improvement in Visual Acuity.  Reading speed is a better parameter than visual acuity when reporting results of visual rehabilitation because  Reading is more demanding than identifying a few optotypes on a visual acuity chart A practicable approach to rehabilitating patients with CF loss
  99. 99. Management Prism Therapy
  100. 100. Management Text Enhancement…
  101. 101. Management…TextEnhancement Conclusion  Boosting the contrast increases the perceptibility of letters and therefore words, then reading gets faster  Increasing the size of character overcomes the scotomatous region thus allowing the non- macular area to fixate extrafoveally  Increasing the luminance of the characters allows for a better recognition.
  102. 102. Psychological/Psychosocialproblems in Retinal Dystrophy Fear of growing blind Fear of ostracism Impaired social life Susceptibility to harassment
  103. 103. Refer TrainTreat Low Vision Service Eye Care Education Detect Educate Identification VI Child
  104. 104. References:  Tasca Jennifer, Edward A. Deglin. Chapter SIX „Common Disorders Encountered in Low Vision‟ in “ESSENTIALS of LOW VISION PRACTICE”, 1ST Edition, BUTTERWORTH HEIMAN,1999  Kathleen Fraser Freeman, Cole Roy Gordon, Eleanor E Faye, Paul B. Freeman, Gregory L. Goodrich, Joan A. Stelmack. Optometric Clinical Practice Guideline Care of the Patient with Visual Rehabilitation(Low Vision
  105. 105. References: Ferraro, J. and Jose, R. T. (1983). Training programs for individuals with restricted fields. In R.T. Jose (Ed.), Understanding Low Vision, American Foundation for the Blind, NewYork. Vol. 14, 363-376. Crossland, Michael D. Visual rehabilitation of patients with macular diseases, in Focus, The Royal College of Ophthalmologists
  106. 106. References: Ajit Kumar Thakur, Purushottam Joshi, Himal Kandel, Subash Bhatta.Profile of low vision clinics in eastern region of Nepal: A retrospective study.British Journal of Visual Impairment 2011 29:215 Elisabeth M. Fine, Eli Peli.Enhancement of text for the Visually impaired.J. Opt. Soc. Am. A 1995;12;1439-1447
  107. 107. References: Jae Hoon Jeong, Nam Ju Moon. A Study of Eccentric Viewing for Low Vision Rehabilitation. Korean J Ophthalmol 2011;25(6):409-416 Berson EL, Mehaffey L III, Rabin AR. A night vision device as an aid for patients with retinitis pigmentosa. Arch Ophthalmol 1973;90:112–6.
  108. 108. References: William H. Ridder III, John B. Slegfried.Chapter 16 „Clinical Electrophysiology‟ in Borish‟s Clinical Refraction, 2nd Edition, BUTTERWORTH HEIMAN Elsevier,2006
  109. 109. AND YOU THINK YOU ARE HAVING A BAD DAY AT WORK !!Although this looks like a picture taken from a Hollywood movie, it is in fact a realphoto, taken near the South African coast during a military exercise by the British Navy.It has been nominated by Geo as "THE photo of the year".
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