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An-Overview-of-Assessment-Techniques-in-Low-Vision.pdf
- 1. An Overview ofAssessment Techniques in Low Vision Dr. John Dean Low Vision Practitioner
- 2. ➢ Impact ofVisual Imparment ➢ Underlying philosophy of Low Vision Assessment ➢ Steps in Low Vision Assessment OUTLINE
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- 4. Psychosocial Impact ofVisual Impairment ● Stages of Grief: 1. Shock and Denial 2. Guilt and pain 3. Anger and bargaining 4. Depression, Loneliness and Reflection 5. The Upward Turn https://www.betterhelp.com/advice/grief/understanding-the-stages-of-grief/
- 5. Low Vision Assessment Underlyingphilosophy The provision of low vision care for children needs to be integrated within eye care and education/rehabilitation services, and it needs to be accessible to all children.
- 6. Steps in LowVision Assessment ● Observation ● Patient History ● Visual acuity: near and distance ● Refraction and prescription of distance spectacles ● Binocularity ● Visual field ● Contrast sensitivity ● Color vision ● Illumination ● Prescription and training of optical low vision devices ● Advice on non-optical devices ● Referral
- 7. Observation ● Observing theclient’s behavior and his physical status gives an information to the severity of the problem. ● Areas to be observed: ○ Postural abnormalities: Head turns/tilts ■ Towards the side of field loss ■ To find the null point of nystagmus
- 8. Observation ● Areas tobe observed: ○ Fixation: eccentric fixation in central scotoma ○ Mobility: speed, accuracy, confidence, with support ○ Appearance: general, clothing, sunglasses, squeezing of eyes ○ Psychological behavior: depressed, angry, lack of confidence, expectant ○ Other disabilities: LD, Down syndrome
- 9. Patient History ● Problemsand vision related needs ● Components: ○ General information: Personal, family, medical history ○ Ocular history: Onset, Prognosis, Duration, Stability, Medical history ○ Motivation and expectation ○ Visual performance (task related) ○ Previous low vision assessment ○ Use of any devices ○ Visual goals
- 10. Ocular Health Examination ●Slit-lamp biomicroscopy ● Ophthalmoscopy ● Light and magnifier
- 11. Visual Acuity ● Takenote of the following: ○ Age ○ Literacy ○ Learning ability ○ Simplicity ○ Familiarity ● Children: Match, Point, Name
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- 14. Visual Acuity: Distance TestPurpose Appropriate/Intended Population 1. Snellen To determine distance visual acuity Test Distance: 20 ft/6m 2. Bailey-Lovie To determine distance visual acuity Test Distance: 4m Individuals who can match or verbalize alphabet or numeric symbols 3. HOTV To determine distance visual acuity Test Distance: 3m Children who are 3 years old or older 4. LEA Symbols (Single-symbol) To determine distance visual acuity Test Distance: 3m Young children who can match or verbalize symbols Those who cannot perform in line-test situations 5. Feinbloom To determine distance visual acuity Test Distance: 3m Children who can accurately discriminate letters and numerals; youth and adults; those with very low vision who need larger optotypes 6. LEA Gratings To determine resolution acuity at near and intermediate distance Test distance: 115cm, 85cm, 57cm, 43cm, 28cm Individuals who are infants or toddlers or who are unable to respond to symbol acuity charts
- 15. Visual Acuity: Testing 1.4m>3m>2m>1m>0.5m 2. Use bigger chart 3m>2m>1m>0.5m 3. Light Projection 4. Light Perception 5. NLP
- 16. Visual Acuity: Recording ●M-notation or M-unit ● Distance/Optotype(size) ● Examples: ○ Distance: 4m/40M
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- 19. Visual Acuity: Recording ●M-notation ● Ex: 8M @ 40cm
- 20. Refraction ● A carefulrefraction is needed ● It can improve distance and near vision
- 21. Refraction ● Subjective refractionis always needed especially when retinoscopy gives no good result. ● Bracketing technique - is a procedure used in subjective refraction in which large and equal steps of dioptric changes are made above and below the presumed correct answer, and then reducing the size of the dioptric changes and shifting the center of the range, until the finest and just detectable blur is induced by equal steps above and below the refractive error. Click to add text
- 22. Bracketing Technique → JND– Just Noticeable Difference Fundamentals of Bracketing: • Embrace: Things are better between the two limits, BOTH limiting lenses should be rejected • Diffferential responses: • “shades of certainty” judged by response speed, tone, or words • Depend on the patient’s discrimination abilities and size of differences between comparisons • Progressively reduce size of bracket: from each bracketing, estimate the final answer. The next bracket should embrace your current best estimate of the answer
- 23. Binocular Vision ● Tests: 1.Lang Two Pencil Test 2. Maddox Rod 3. Sterofly
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- 25. Contrast Sensitivity ● HidingHeidi ● Lea Symbols ● Lea Numbers ● Mars Perceptrix Test
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- 27. Lighting/Illumination ● Room illumination ●Day ● Night ● Task illumination
- 28. Monitoring/Follow-up ● To identifysuccess: ○ Can the client to the tasks they want to do? ○ Are they using the spectacles/low vision device? ● To identify any new problems ● To adapt the distance correction ● To adapt the magnification/non-optical devices
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