write an eassay on human eye
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Answer:
Eyes are the chief organs of vision in human body and hence termed as photoreceptors.
The paired eyes in man are located inside bony sockets of skull called orbits. An eye is almost a spherical ball, guarded by two eye lids: upper eye lid and lower eye lid which can move frequently.
These eye lids are bordered by hairs forming eye-lashes. In man the third eye lid is vestigial and lies at the corner of the eye and is known as plica semilunaris. On the margins of eye lids are small Meibomian glands which secrete an oily substance for lubricating the eye lids and for holding a thin film of tears underneath
Below the outer corner of the upper eye lid are lacrimal or tear glands to produce tears that keep the eye ball (conjunctivae) moist. The tear flows across the front of the eye and excess of tears at the time of emotion are drained into the small lacrimal sac .at the inner margin from where they are then discharged by means of nasolacrimal duct into the nasal passage ways.