1. Vision Science in Optometric Testing Jay Rumsey, OD, FAAO College of Optometry Nova Southeastern University

2. Vision Acuity Stimulus: Letters, Numbers or Symbols Response: Threshold limit of correct response to decreasing stimulus sizes

3. What is the smallest row on which you can A read more that B ! of the letters? C D E A. 63 B. 40 C.20 D. 16 E. 10

4. What kind of task is this? A. Detection B. Descrimination

5. Vision Acuity Variables Size Shape (font) Contrast & Color Crowding Off-fovea viewing Receptor sensitivity

6. What method are you using? A. Method of Limits B. Method of Constant Stimuli C. Method of Adjustment

7. Vision Acuity Charts Snellen Chart ETDRS Chart Early Treatment of Diabetic Retinopathy Study

8. In this test, do you use? A. Ascending Series B. Descending Series C. Both Ascending and Descending Series

9. Vision Acuity Speciality Needs Music Newsprint / Phonebook/ Catalogues Medicine Labeling Prescribed and OTC Color and Packaging Effects Specialized occupations Computer Displays Spreadsheet printouts

10. Computer Generated Vision Acuity Charts

11. Contrast Sensitivity Stimulus: Detail item on background Black on White vs Black on Dark Gray / White on Light Gray Response: JND of changes between item and background

12. Contrast Sensitivity C O N T R A S T Spacial Frequency (cycles per degree)

13. Contrast Sensitivity Sometimes the VA target size is constant with the contrast display Pelli-Robson changes to the letters. Chart Causes of loss of CS are age, cataracts, media changes, contact lenses (among other things) MARS Letter Contrast Sensitivity Chart

14. Contrast Sensitivity Sometimes the VA target size changes with the contrast display staying constant. Example: Bailey-Lovey Chart Dramatic demonstration of effects of cataracts when more than two lines lost between presentation of same target with 100% and 10% contrast Similar to ETDRS chart (Early Treatment of Diabetic Retinopathy Study)

15. Vision Fields Stimulus: Target of either Variable size but constant intensity Variable intensity but constant size Response: Threshold limits of sensitivity to stimulus changes

16. Goldmann VS Automated VF Displays

17. Goldmann Bowl Perimeter

18. Automated Field Instuments

19. Vision Fields Scales Intensity to Sensitivity to Decibels Log Base 10 Sensitivity DB (x10) Bright: Log 10,000 = 4 0 0 Log 1000 = 3 1 10 Log 100 = 2 2 20 Log 10 = 1 3 30 Log 0 = 0 4 40 Log 0.1 = -1 5 50 Dim: Log 0.01 = -2 Automated Instrumentation covers a 5.1 log range

20. Vision Fields Sensitivity

21. VF Relationships of Size to Luminance Because of retinal summation and receptor sizes: Increasing target area by 4 times is equivalent to raising luminance by 0.5 log units ~ 5 dB change to sensitivity is considered significant for VF detection of changes.

22. What is the sensitivity range for an automated VF instrument? A. 0.51 dB B. 0.51 log units C. 5.1 dB D. 51 log units E. 51 dB

23. Vision Fields Screening Test From Central Reference Absolute Threshold Stimulus presented at maximum brightness Recorded only as Seen or Not Seen Three-Zone Test Stimulus shown 6dB above expected sensitivity If not seen, presented again at maximum Recorded as Seen @ Expected, Seen @ Max or Not Seen

24. Vision Fields Threshold Tests Full Threshold Stimulus presented 6dB above expected If seen, reduce stimulus by 4dB, until not seen Increase by 2dB until seen and record dB level If not seen, increase stimulus by 4dB, until seen Decrease by 2dB until not seen and record dB level Full from Prior Data Same presentation, but initial stimulus intensity is 6dB above data collected from past testing.

25. Full Threshold Vision Fields Which method is this? A. Limits B. Constant Stimuli C. Adjustment D. Forced Choice E. Staircase

26. Color Vision Stimulus: Color discs or Colored Symbols Response: Sensitivity to detectable changes to wavelengths at set intervals.

27. Color Vision Tests Cone Stimulation Color Perception

28. Color Vision Tests Ishihara Cards What type of test is this? A. Detection B. Descrimination

29. Color Vision Tests Farnsworth D-15 D-100

30. D-15 Color Vision Testing What method is this? A. Limits B. Constant Stimuli C. Adjustment D. Forced Choice E. Staircase

31. Stereopsis Stimulus: Images falling within Panums Fusional Area on retinas of two eyes. Response: Ability to detect smallest separation of images

32. Steropsis Tests Red/Green (Blue) Cards Poloroid slides Free Space (Random Dot) Images

33. Which symbols do you see in the fused Random Dot region? A. Circles B. Boxes C. Triangles D. Stars E. I see nothing!

34. Fixation Disparity Stimulus: Two line stimuli presented separately to each eye Response: Subjective alignment of two vertical and two horizontal lines on retinal receptors JND of separation of alignment of lines

35. Fixation Disparity Significant for EOM alignment control and measurement.

36. Has this lecture been helpful? A. Yes B. No C. Sorry, I fell asleep