Accommodation Flashcards
Accommodation
process to make and maintain a focused retinal image
changes lens power and lens curvature
What causes the lens changes in accommodation?
Ciliary Muscle
Ciliary Muscle
parasympathetic innervation
contracts to cause lens changes and releases resting tension of zonules
Edinger-Westphal Nucleus
where parasympathetic pathway starts
3 physiological changes in accommodation
Triad or Near Reflex
eye accommodation
pupil constriction
eyes converge
Change in pupil size
controls light
modifies depth of focus
varies any optical aberration
Reflex Accommodation
auto adjustment to maintain focused retinal image
response to blur
important for scanning eye movements
Vergence Accommodation
induced during fusional vergences
leads to convergence accommodation/ convergence ratio (CA/C)
Proximal Accommodation
refocusing from perceived nearness of target
stimulated by targets w/in 3 m of person
Tonic Accommodation
“Lead of Accommodation”
resting level of accommodation (0.5 - 1.5D)
due to baseline stable parasympathetic innervation
reduces with age
Factors that affect Accommodation
blur, convergence, proximal issues, pharmacology, minus lens, disease
Retinal image factors that affect Accommodation
contrast, spatial frequency, retinal image motion
Non-retinal factors that affect Accommodation
mood, voluntary effort, target luminance, training
Optical Cues that affect Accommodation
offer info about directionality, astigmatism, aberrations
Non-optical cues that affect Accommodation
size, proximity, apparent distance, depth cues