Optics: Pupillary Optics Flashcards
The iris has no….
optical power
The iris forms the _____ ____ of the eye
Aperture stop
The opening of the aperture stop(iris) is known as the ______.
Pupil
What two muscles control pupil size?
Sphincter pupillae- pupil constriction
Dilator pupillae- pupil dilation
The iris is designed to prevent _________ ____ from getting to the lens/retina
Undesirable light
The iris is desgined to have _____ granules in stroma and epithelium (brown eyes)
Melanin
Blue and green colored irises has granules in the ________.
Epithelium
The iris is the ___ reliable biometric identification system
Most
What are the five functions for the iris?
-Stops undesirable light
-Regulates retinal illumination
-Controls depth of field
-Helps in controlling retinal blur
-Help design optical instruments
The entrance pupil EP of an optical system is the…
The image of the aperture stop from in the object space
The exit pupil XP is the…
Image of the aperture stop formed in the image space
Entrance pupil in eye is a ____, _____, and _______image formed 0.5 mm in front of the real pupil
Virtual, erect, magnified image
What part of the iris stops undesirable light
Pigmented tissues
how does the iris regulate retinal illuminance
Pupil size and retinal layers
How does the iris control depth of field?
Makes the pupil smaller
How does the iris help control retinal blur
Diffraction and aberrations
How does the iris help design optical instruments
Entrance pupil and exit pupil
Exit pupil is _____mm behind the real pupil and ____% larger than the real aperture
0.07mm
3.1% larger
The level of ____ is the most important factor affecting pupil size
Illumination
The pupil response to an increase in illumination is to ____ the pupil size
Decrease
With low illumination, there is a latency of ____ seconds before constriction of pupil
0.5 seconds
With increased illumination, the latency decreases to ____ seconds
0.2 to 0.3 seconds
Pupil response to full withdrawal of light may take up to a ____
A minute
The pupil has more response when light distribution is in the ____ visual field
Central visual field
The pupil has less response when light distribution is in the ______ visual field
Peripheral visual field
Pupil response to changes in light level is mediated by both ___ and ____ photoreceptors
Rod and cone
Direct light reflex
The constriction of the pupil due to direct light simulation
Consensual light reflex
Pupils of both eyes respond equally to stimulation of only one eye
Near reflex
The pupil decreases in diameter when the eyes converge or accommodate
Pupil centration
Pupil is decentered by 0.5mm nasally relative to the optical axis
As age increases, pupil size _____
Decreases ( senile miosis)
Mydriatics affect on pupil
Simulates sympathetic nervous system dilates the pupil
Miotics affect on pupil
Stimulates parasympathic system, constricting the pupil
Pleasant mental images affect on pupil
Increases pupil size
Unpleasant mental images affect on pupil size
Decreases pupil size
To increase the depth of field, the pupil will _____.
Decrease in size
Depth of field is the range of distance over which the system’s detector….
Cannot detect any change in focus
DoF for the human eye is between ___D to ___D
0.5 to 1
If you observe someone’s pupil from oblique angels, you will see that
The pupil becomes narrower in the direction of view
The apparent area of the pupil decreases as the oblique viewing angle is ______
Increased
The decreases in diameter with viewing angle has two important implications:
- The oblique aberrations and hence retinal image quality
- The amount of light entering the eye from oblique angles, and hence the brightness of a peripheral retinal image
Light entering the eye and reaching the fovea depends on the ____ ____ of the pupil
Entry point
Light entering the eye near the center of the pupil appears ____ than light entering near the edge
Brighter
For ______ pupil diameters, aberrations cause deterioration in retinal image quality
Large
For _____ pupil diameters, diffraction limits image quality
Small
The optimum pupil diameter is
2-3mm
To get maximum field of view when looking through an eyepiece into an eye, you have to align the eye’s ______ pupil with the external system’s _____ pupil
Entrance, exit
