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Catching Up with Ocular Imaging: New Vision Tests Reveal Early Loss in Eye Disease
1. The Dilemma
a. Structural imaging has outpaced clinical tests of visual function
b. New tests which go beyond “20/20VA” to reveal subtle changes are needed
c. New contrast sensitivity (CS) and color vision (CV) tests are described
2. CS Basics
a. Definition
b. CS function
c. Relation to visual acuity (VA)
d. Gratings vs. letters
e. FDA recommendations and current tests
3. CV Basics
a. Why we see color in the visible range
b. Color metrics: Munsell and CIE
c. Neural coding of normal and abnormal CV
d. Hereditary vs. acquired CV
e. CV tests
i. Pseudo-isochromatic plate tests
ii. Hue arrangement tests (D15 and FM 100 hue)
iii. Lantern test
iv. Anomaloscope
4. Small Letter CS
a. Given` steep right-side slope of CS function which relates CS to size (VA)
b. Small change in VA associated with larger in change in small letter CS
c. Hence small letter CS is a more sensitive index of early visual loss
d. Supporting evidence
5. Super Vision Test
a. Back-illuminated letter chart with ETDRS VA and small letter CS
b. VA: 20/32 to 20/5; CS: 20/25 letter size at range of contrasts
c. Sensitivity in PRK, LASIK, early cataract, macular edema
d. Relation to higher order aberrations
e. Testing at low luminance
6. Cone-Specific Contrast Sensitivity (Cone Contrast Test; CCT)
a. Letters visible to single cone types (red, green and blue)
b. Presented in decreasing steps of visibility (cone contrast)
c. Quantifies lowest contrast seen for R, G and B cones
d. Results in hereditary and acquired color deficiency
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7. CS and CV Application
a. Refractive surgery
b. Cataracts
c. Keratoconus
d. CV Deficiency
e. Ocular and neurological disease
8. Neuro-Vision Test Card
a. CS and red, green and blue CV thresholds
b. Blind spot measurement
c. Low luminance Amsler Grid
d. Fixation disparity
e. Aniseikonia
9. The Future
a. Mobile device applications – initial results with…
i. Ipad
ii. Iphone
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