Physiological constants (Michaelmas) Flashcards
What are the focusing elements of the eyes?
- Cornea: Contributes 2/3 (~48D) of overall focusing power of eyes.
- Lens: Contributes 1/3 (~18-26D) of overall focusing power of eyes.
What is the maximum focusing power of the eyes?
57D
What is the absolute threshold if luminance for vision?
10-6 cd/m2
What is the width of maximum range of sensitivity for vision?
~1015
What is the accommodation range for an emmetrope?
12D
What is the width of a pointspread function?
1.5 arc minutes (~90 arc seconds)
What is the diameters of the pupils?
2-8 mm
What is the minimum photoreceptor spacing in the retina?
~2.3 μm (~30 arc seconds)
What angle is subtended by the fovea?
~1o
What angle is subtended by the optic disc?
~5o
What is the peak absorption wavelength of rods?
~500nm
What is the peak absorption wavelength of red cones?
564nm
What is the peak absorption wavelength of green cones?
534nm
What is the peak absorption wavelength of blue cones?
420nm
What is the critical fusion frequency in rod-mediated scotopic vision?
~15Hz
What is the critical fusion frequency in cone-mediated photopic vision?
~60Hz
What is the peak absorption wavelength of red cones?
558nm
What is the peak absorption wavelength of green cones?
531nm
What is the peak absorption wavelength of blue cones?
419nm
What is the normal hearing range for humans?
20Hz - 20kHz
What is the minimum sound pressure detectable by the human ear?
20μPa
What is roughly the pain threshold for hearing at all frequencies?
~120dB SPL
What is the transformer ratio of the middle ear apparatus?
18.2
What is the resting potential of endolymph?
+100 mV
What is the number of axons in the cochlear nerve?
~30,000
What is the minimum and maximum interaural time differences detectable by the ears?
10 - 660μs
What is the minimum interaural intenisty difference detectable by humans?
1 dB
