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20 Cards in this Set
- Front
- Back
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Maximum human accommodation during childhood |
10-15 D |
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Age at which complete loss of accommodation occurs |
50 years |
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Definition of accommodation |
A dynamic, optical change in the dioptric power of the eye allowing the point of focus of the eye to be changed from distant to near objects |
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Optical infinity for the unaccommodated, emmetropic eye |
6 m or 20 ft |
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Depth of field |
The range over which an objectcan be moved towards or away from the eye in object space without a perceptible change in the blur or focus of the image |
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Effect of pupil size on depth of field |
Depth of field increases with decreasing pupil size |
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Parts of the ciliary muscle |
Longitudinal, radial and circular |
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Anterior insertion of the ciliary muscle |
Scleral spur and trabecular meshwork |
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Posterior attachment of the ciliary muscle |
Stroma of the choroid |
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Composition of zonules |
Elastin |
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Effect of accommodation on the ciliary body |
Inner apex moves forward and towards the axis of the eye |
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Effect of accommodation on the lens |
Decreased diameter, increased thickness, and central anterior and posterior surface curvature. |
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Effect of accommodation on anterior chamber depth |
Decreases |
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Effect of accommodation on vitreous chamber depth |
Decreases |
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Receptors responsible for ciliary muscle contraction |
Muscarinic receptors |
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Mechanism of pilocarpine being less effective in darker coloured irides |
Binding of drug to pigment epithelium resulting in decreased bioavailability |
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Mechanism of action of cycloplegic agents |
Competitive inhibition of muscarinic agonists |
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Subjective measurement of accommodation |
Push-up method, negative lens blur |
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Instruments for objective accommodation measurement |
Autorefractor, refractometer, aberrometer |
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Presbyopia |
Gradual age-related loss of accommodative amplitude |
