Accommodation Reflex

Explanation : Accommodation is a reflex action. When a person looks at a near object after seeing a far object, three adjustments are made in the eyeballs:
1. Convergence of the eyeballs due to contraction of the medial recti
2. Constriction of the pupil due to the contraction of constrictor pupillae of iris
3. Increase in the anterior curvature of the lens due to contraction of the ciliary muscle.
Ref : Sembulingam 6th edition (Page- 997)

Explanation : In addition to increase in anterior curvature of the lens, two more adjustments are made in the eyeball during accommodation for near vision.
1. Convergence of both eyeballs: It is necessary to bring the retinal images on to the corresponding points
2. Constriction of pupil: It is necessary to:
i. Increase the visual acuity by reducing lateral chromatic and spherical aberrations
ii. Reduce the quantity of light entering eye
iii. Increase the depth of focus through more central part of lens as its convexity is increased.
Ref : Sembulingam 6th edition (Page- 996)

Explanation : The center for accommodation lies in frontal eye field (area 8) that is situated in the frontal lobe of cerebral cortex.
Ref : Sembulingam 6th edition (Page- 997)