Accommodation is due to ?
Correct Answer: Contraction of ciliary muscles
Description: Ans. is 'b' i.e., Contraction of ciliary muscles Accommodation Accommodation of the eye refers to the act of physiologically adjusting crystalline lens elements to alter the refractive power and bring objects that are closer to the eye into sharp focus. Our eyes have been provided with a unique mechanism by which we can even focus the diverging rays coming from a near object on the retina in a bid to see clearly. This mechanism is the accommodation. In accommodation there occurs increase in the power of crystaline lens due to increase in the curvature of its surfaces. Accommodation is due to contraction of ciliary muscles. Near point and far point are related to accommodation The near point is the closest distance between an object and eye that makes possible the formed image to be focused, i.e., it is the point in which accommodation is maximum (ciliary muscles are maximally contracted). Far point is the most distant point from the eye in which an object can be placed and its image is still focused, i.e., it is the situation of maximum relaxation of ciliary muscles. In myopia near point and far point of vision come closer and in hypermetropic near point becomes more distant. Anomalies of accommodation are : (i) Presbyopia, (ii) Insufficiency of accommodation, (iii) Spasm of accommodation, (iv) Paralysis of accommodation.
Category:
Ophthalmology
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