1. AMBLYOPIA - 2 Ralph P. Garzia

2. Non-visual acuity deficits in amblyopia  reduced contrast sensitivity  deficient accommodative skills amplitude, facility, lag  deficient oculomotor skills fixation, pursuits, saccades  spatial uncertainty  spatial distortion  eccentric fixation

3. Amblyopia & contrast sensitivity Note the differences in CSF function between amblyopes

4. Amblyopia & accommodation normal accommodative stimulus-response curve

5. Amblyopia & accommodation Amblyopic accommodative stimulus-response curve

6. Accommodation & amblyopia Effects of eccentric fixation Normal accommodative responses as a function of amount of eccentric fixation or retinal eccentricity

7. Accommodation & amblyopia  Latency increased  Gain reduced  Amplitude reduced  Facility reduced

8. Amblyopia & fixation instability fixating a + > steady fixation >

9. Amblyopia & steady fixation EOG’s more instability > with greater acuity loss >

10. Amblyopia & smooth pursuits EOG of smooth pursuit to sinusoidal stimuli  acceleration  uniform velocity  saccadic intrusions

11. Amblyopia & saccades Dysmetria multiple small saccades in the direction of the target displacement

12. Oculomotor deficits in amblyopia  Fixation unstable increased drift amplitude  Saccades increased latency decreased peak velocity dysmetric  Pursuits increased number of loses of fixation increased number of saccadic intrusions decreased gain

13. Snellen Acuity vs grating acuity Anisometropic amblyopes A’s cluster on the 1:1 line Strabismic amblyopes S’s are far to the right normal eyes > Strabismic amblyopes:  oculomotor problems  spatial distortion problems

14. Oculomotor effects  Snellen vs. grating acuity VEP’s CSF Interferometry What these have in common is a spatially redundent pattern.

15. Amblyopia and visual acuity behavior Typical letter confusions made by amblyopic eyes Note the confusion  similar shapes  sequence errors  transpositions What’s the VA?

16. Characteristics of visual acuity measurements in amblyopia  crowding effects  distortions / misperceptions  loss of place / out of order  noisy  short and long term variability

17. Amblyopia and visual acuity behavior Typical letter confusions made by amblyopic eyes Note the confusion  similar shapes  sequence errors  transpositions What’s the VA?

18. Amblyopia & contour interaction Test stimulus used to determine contour interaction

19. Contour interaction normal eyes and amblyopic eyes Contour interaction as multiples of gap width (critical detail) normal eyes > amblyopic eye > ci effects are similar in normal & amblyopic eyes as a function of visual acuity

20. Psychometric chart  Landolt C’s are the targets  There are 8 at each VA level  There are equal spacing between each of the test optotypes (C’s) and the nearest contour on all 4 sides  Spacing is equal to the overall size of the test optotypes or 5x’s the critical detail

21. Psychometric or “S” graph  Normal eye has a steep function  Amblyopic eye has a very gradual drop- off of visual acuity

22. Crowding phenomenon  Entire chart vs.  Whole line vs.  Single letter

23. Eccentric fixation & visual acuity combine all the lines and get a best fit curve or linear formula: MAR’=.4(ef∆)+1 e.g. ef=1deg=1.75∆ MAR’=.4(1.75)+1 MAR’=0.7+1=1.7’ VA=20/34

24. Visuoscopy central fixation > nasal eccentric fixation >

25. Haidinger’s brushes Fixate on the dot: where are the brushes perceived