Note the structures through which light passes to reach the

Note the structures through which light passes to reach the retina. Write these structures in order.

Solution

The order of light passage from outside till to retina:

Initially light enters cornea & sclera layers ---> pupil ---> circular Iris that surrounds pupil using pupillary sphincter muscle --> light enters lens---> retinal layers ---> rods & cones

Explanation:

Neural layer is the inner layer; it is in contact with the vitreous humour. The neural layer contains three distinct populations of cells namely,

From the outer (pigmented epithelial layer) to the inner (towards the vitreous humour), these cells are arranged in the order of, photoreceptors, bipolar cells, ganglion cells.

Photoreceptor cells (rods and cones) are communicated with the nerve cells called bipolar cells. These bipolar cells synapse with the ganglion cells, which transmit the impulses to the brain via axons in the optic nerve.

Retina is the innermost nervous coat of eyeball, and it contains some special photo receptor structures called “rods and cones.” These rods and cones receive the light and send impulses to the optic nerve.

The inner nuclear layer of the retina contains oval shaped bipolar cells. The dendrites of bipolar cells synapse with the photoreceptor cells, and axons of bipolar cells synapse with the ganglionic cells.

Ganglion cells are multipolar cells present in the ganglion cell layer of retina; their axons are present in the inner surface of the retina, forming the optic nerve. The dendrites of ganglion cells synapse with the axons of bipolar cells. These ganglion cells transmit the impulses to the brain via axons in the optic nerve.