Formation of an Image on the Retina. In the same manner that a glass lens can focus an
image on a sheet of paper, the lens system of the eye can focus an image on the retina. The image is
inverted and reversed with respect to the object. However, the mind perceives objects in the upright
position despite the upside-down orientation on the retina because the brain is trained to consider an
inverted image as normal.
Mechanism of ―Accommodation‖ In children, the refractive power of the lens of the eye can
be increased voluntarily from 20 diopters to about34 diopters; this in an ―accommodation‖ of 14
diopters.To do this, the shape of the lens is changed from that of a moderately convex lens to that of a
very convex lens. The mechanism is as follows. In a young person, the lens is composed of a strong
lastic capsule filled with viscous, proteinaceous, but transparent fluid.
