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LET’S TALK LOW VISION

LET’S TALK LOW VISION. Suleiman Alibhai, O.D. Retina Group of Washington Krista M. Davis, O.D., F.A.A.O. Columbia Lighthouse for the Blind. Eye Anatomy. Definitions. Legal Blindness Best corrected distance visual acuity of 20/200 or worse in better eye

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LET’S TALK LOW VISION

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  1. LET’S TALK LOW VISION Suleiman Alibhai, O.D. Retina Group of Washington Krista M. Davis, O.D., F.A.A.O. Columbia Lighthouse for the Blind

  2. Eye Anatomy

  3. Definitions • Legal Blindness • Best corrected distance visual acuity of 20/200 or worse in better eye • Horizontal visual field of 20 degrees or less at widest point in the better eye • Low Vision • Worse than 20/60 in the better eye • Significant field loss • Impaired function

  4. Goals of Low VisionManagement • Increase functionality • Make the most of the remaining vision • Provide link to community resources and support services • Education

  5. Macular Degeneration Glaucoma Diabetic Retinopathy Stroke/ brain injury Retinitis pigmentosa Optic Nerve disease Albinism Nystagmus Cortical Visual Impairment Common Conditions

  6. Functional Effects of Low Vision • Loss of central vision (visual acuity) • Loss of peripheral vision (visual field) • Glare and contrast

  7. Issues Related to Decreased Acuity • Difficulty reading • Problems writing/ completing paperwork • Inability to recognize distance objects and faces

  8. Issues Related toVisual Field Loss • Location of scotoma important! • Generalized loss of visual field difficult to compensate for • Mobility and independent travel • Reading may require adaptations

  9. Issues Related to Contrast • Need for additional lighting • Problems with glare • Increased adjustment to changes in illumination • Visual discomfort and fatigue

  10. Exam Sequence • History/ intake • Visual acuity • Visual field testing • Pupils • Extraocular muscle testing • Refraction • Color vision and Contrast Testing • Ocular Health

  11. Types of Acuity Charts • Distance • Snellen (projection) • Feinbloom/ SOSH • ETDRS • Lea Symbols • Near • Single letter • Continuous text

  12. Distance Charts

  13. Near Charts

  14. Interpreting Near Acuity • Threshold acuity • Difference between single letter and continuous text • 1.0 M = 20/50 = 8-10 point font • Need to look at working distance • Jaeger charts nonstandard • Typical sizes • Newspaper = 1.0M • Children’s books = 1.2 – 1.6M • Large print = 1.6 – 2.0M • Newspaper headlines = 4.0 – 5.0 M

  15. Visual Field Testing • Confrontation • Arc perimeter • Vision Disc • Automated perimetry • Goldmann perimetry

  16. Color and Contrast Tests • Ishihara • Color Vision Testing Made Easy • D-15 • Pelli-Robson • Vistech Contrast System • Mr. Happy • Hiding Heidi

  17. Color Vision Tests

  18. Contrast Tests

  19. Magnification • Enlarges image on retina to stimulate more retinal cells • Can be achieved in many ways • Relative Distance • Relative Size • Optical / Angular • Electronic

  20. Low Vision Devices • Distance • Near • Field enhancement • Non-optical

  21. Distance Devices • Hand held telescopes • Mounted telescopes • Electronic systems

  22. Telescopes

  23. Electronic Distance Systems

  24. Near Devices • Spectacles • Prismatic ½ eyes • Full-field microscopes • Magnifiers • Hand held vs. stand • Illuminated vs. non-illuminated • Telemicroscopes • Electronic Devices

  25. Spectacle Microscope

  26. Near Loupe

  27. Hand Held Magnifiers

  28. Stand Magnifiers

  29. Electronic Magnifiers

  30. Non-optical Devices • Glare reduction devices • Contrast enhancement devices • Computer software • Accessory devices • Talking watches, clocks, etc • Writing guides • Tactile markers

  31. Glare and Contrast

  32. Lighting

  33. Other Non-optical Devices

  34. Adaptive Computer Equipment

  35. Additional Services • Orientation and mobility training • Independent living skills training • Support groups • Braille instruction • Computer training • Genetic counseling

  36. Community Resources • Support groups • Paratransit Services • Books on tape • Audio described performances • Tactile tours • Large print publications • Educational services

  37. Communication Goals • Educate patient on eye condition • Help them to understand what options are available and how to use/ care for tools • Glasses • Low vision devices • Technology • Community resources • Educate parents and teachers/ professionals on functional implications

  38. Functional Implications • Print size • Visual efficiency and fatigue • Mobility issues • Positioning/ classroom placement • Lighting/ glare reduction needs

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