visual perception nbeo.txt

6 mo

20/600 (1 cycle/degree)

3-5 yrs

20/50 (12 cycles/degree)

High sensitivity and high false positives

High specificity and high false negatives

• Probability of a test giving a positive result given that the signal(disease) is present
• Disease present =positive

Probability of a test giving a negative result when signal(disease) is not present

Saying there is a signal when there really isn't

Not saying there is a signal, when really there is

555 nm

507 nm

Different lumens from different wavelengths being summed together as total lumens

Surfaces that scatter light equally in all directions

Low sensitivity

twice as sensitive as photopic

• At this wavelength, there is no difference between photopic and scotopic sensitivities
• Dusk, both photopic and scotopic is being used

After 650nm, shorter wavelengths become brighter in scotopic vision and visa versa

• How well we pick out a spot of light on a dark background
• Light adaptation
• Rod saturation

Any number of photons within a given set diameter photopic or scotopic will appear as only one light

• Regardless of number of photons is a given time, it will appear as one single light
• Photopic 10ms
• Scotopic 100ms

The angle at which light strikes cones strongly affects the light

• Missing one of three cones
• protanope
• deuteranope
• tritanope

Have all 3 pigments, but one is weaker

Outer retinal disease

• Inner retinal disease
• Optic nerve
• Visual pathway

Color

How vivid the color is

• 600/snellen denominator
• Divide cycles by degree by 30 to get snellen form