1. Cortical Vision Loss damage of one or both occipital lobes of visual cortex

2. Progressive Visual Impairment regular eye care & self-monitoring diabetes posterior vitreous detachment glaucoma cataract

3. OPTICS & LOW VISION DEVICES

4. Basic Optics The Composition of Light The Measurement of Light Refraction- the bending of visible light rays –index of refraction- speed of light passing through various media Refraction & the ocular system

5. The Optics of Lenses Structure of a lens Snell's law- the line that will travel upon exiting glass focal point or image point- where light rays come together & converge on a point

6. Types of lenses spherical lenses –convex or plus lenses bulge outward –planoconvex- bulges on one side –chromatic aberration- light disperses as are colors in a prism –biconcave- bulges inward on both planes –planoconcave- bulges inward on one side – cylindrical lenses –plano lenses- lens cut flat on both sides –combination of lenses –prism lenses- moves light rays into functional field

7. Lenses for Refractive Errors Myopia (nearsightedness) = biconcave (minus) Hyperopia (farsighted) = biconvex (plus) Astigmatism (irregular cornea) = cylindrical + axis (location on cornea) Strabismus = prisms (base in or out)

8. Measurement of Lenses focal distance- fd power is measured in diopters D

9. Types of Magnification Relative distance magnification Relative size magnification Angular magnification Projection magnification

10. Near Vision Optical Devices Microscopes Magnifiers handheld magnifiers bar magnifiers

11. Near Vision Optical Devices Stand magnifiers Illuminated magnifers

12. Distance Vision Optical Devices Telescopes Hand-held monocular telescopes Clip-on monocular telescopes

13. Spectacle-mounted telescopes full-field telescope systems bioptic telescopes Contact lens telescopes Behind-the-lens telescopes

14. Non-Optical Systems Illumination 1. types of light 2. position of light 3. adaptation of light to dark 4. glare Illumination control Nonoptical magnification

15. Electronic Systems Common electronic systems Closed circuit TVs (CCTVs) Computer systems Other magnification systems

16. Field-Expansion Systems Bioptics Fresnel prisms

17. CLINICAL LOW VISION Purpose of an evaluation Referral for an evaluation

18. Sequence of a Typical Evaluation Members of the Low Vision Team

19. Sequence of a Typical Evaluation Case history Preliminary observation Distance visual acuity testing –measurement charts fixation refers to the ability of the individual to hold his attention to the object being viewed –distance acuity notations – assessment of young children i. observation ii. tests of visual functions –special considerations

20. Functional Vision Testing Behavioral OKN (optokinetic nystagmus)- cortical PLT (preferential looking test)- Teller acuity Chromatic Luminance- contrast sensitivity Tracking a toy or light- see textbook for sizes and distances

21. Electrophysiological VER- Visual Evoked Potential (visual pathways) ERG- Electroretinogram (cone & rod retinal function) EOG- Electrooculogram (measures charge & potentials of eyes)

22. Subjective Acuity LEA Charts Snellen Tumbling E CSF- Contrast Sensitivity Function Flicker Fusion- macular function Color- Ishihara Visual Fields Confrontation Ganzfeld globe

23. Visual Efficiency Testing ISave (APH) Program to Improve Visual Efficiency (Barraga)

24. Near Visual Acuity Testing 1. measurement charts 2. near-acuity notations 3. special considerations

25. Refraction determination of refraction retinoscopy- streak of light reflex instruments for refraction trial frame & lens set

26. Color Vision Testing Ishihara color plates Farnsworth D15

27. Contrast Sensitivity Testing

28. Interpretation of the Eye Report CUMULATIVE RECORD OF VISUAL FUNCTIONING Name:Sex:DOB: Parent/Guardian: Address: Home Telephone:Work Telephone: Schools attended:Location: Dates: ______________________________________________________ Visual Information Eye condition Ophthalmologic findings Eye Surgery Eye Medications

29. Eye Report Visual AcuityODOSOUOD OS OU (without correction)(with correction) Distance vision Near vision ODOS Visual fields (tested w/with correction) (reported central & peripheral w/blind spot) Color vision SphereCylinderAxis Refractive error OD bifocal OS Bifocal

30. Eye Report Strabismus Binocularity Stereopsis Is eye condition stable?

31. Eye Report Visual Aids Glasses prescribed:Date: To be worn when? To be worn where? Low Vision Aids prescribed: Classroom aids: Print point size Lighting Reading aids (lamps, stands, globes) Magnification devices Telescopic devices Visors Shields Tables Pencils, Pens, Markers * Paper Electronic Aids Computer glare filter Zoom Text Software CCTV

32. Eye Report I. Conditions for Optimal Visual Functioning A. Prefers to control natural light by: Wearing tinted glasses Adjusting window shades Wearing visors Seeking existing shade areas Creating shade areas Moving to source of light Turning to source of light Turning from source of light

33. Eye Report B. Prefers to control artificial light by: Direction of source (specify) Degree of intensity (specify) Prefers combined diffused and directed light Prefers incandescent light Prefers fluorescent light Prefers halogen light Prefers a glare-free work surface (specify) Prefers absorbent work surface Prefers limited work surface

34. Eye Report C. Improves own visual functioning by (specify optical aids & circumstances)

35. Eye Report D. Audiovisual viewing Prefers print point: Prefers black & white (specify distance) Prefers color (specify distance) Type of illumination Dimly illuminated screen Prefers high or low contrast (specify) Prefers viewing distance of reading materials: Prefers viewing distance from computer: The following audiovisual materil cannot be seen from the student's desk:

36. Eye Report Visual Functioning Under Optimal Conditions: A. Outdoors Can easily adapt to sudden changes in illumination Can visual identify an individual (specify distance) Can distinguish between lawn & sidewalk Can distinguish lines on pavement such as for crosswalks & safety zones Can visually avoid stationary obstructions before physical contact Can detect variations of walking levels stepscurbsramps Can detect ball in air (specify size) Can recognize features of a persons & objects (specify distance) Can usually see traffic lights at night Can usually see traffic lights during the day Can use visual landmarks to establish line of direction Can select own visual landmarks While walking From a moving vehicle Can see if a curb is absent low lying has rounded corners Can see house numbers from street or sidewalk Can see direction of moving escalators Can see unoccupied seat in auditorium bus Adaptation time from indoors to outdoors from outdoors to indoors

37. Eye Report. Indoors Can locate source of natural light Can locate source of artificial light Reaches for objects within arm's length without search Moves toward objects over 5 feet away Can see hands on wall clock Can differentiate between small & large hands on clock Can identify without touch eating utensils placed at random on desk or table Can imitate pose or gesture of teacher at _____distance Uses APH graph paper: 4" 1" 1/8" Uses APH lines paper with pencil marker pen Uses APH outline maps Reads chalkboard at ____ distance Reads dry-erase at ___ distance Can use pictures in large-type books color black & white Specify smallest print size Can read numerals on paper money Identifies coins by sight or touch Primary color identification

38. Report of Clinical Findings Other Considerations Individuals with multiple disabilities Emotional aspects of the evaluation Funding issues

39. Visual Functioning Visual AbilityFindingImplications –Visual acuity –Visual fields –Contrast sensitivity –Light sensitivity –Color vision –Oculomotor control –accomodation