Eye

: This article refers to the sight organ. See Eye (disambiguation) for other usages.

Peripherals of the eye

The orbit

In many animals, including humans, with binocular vision, the eyes are inset in the skull, in the eyesockets. This way, a stick or plate striking the head will not damage the eye, unless it breaks the skull.

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Reflexes

Most creatures will automatically react to a threat to its eyes (such as an object moving straight at the eye, or a bright light) by covering the eyes, and/or by turning the eyes away from the threat. Blinking the eyes is, of course, also a reflex.

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Eyebrows

In humans, the eyebrows redirect flowing substances (usually rainwater) away from the eye. Water in the eye can alter the refractive properties of the eye and blur vision. It can also wash away the tear fluid, and its beneficial effects, and can damage the cornea, due to osmotic differences between tear fluid and freshwater.

Related Topics:
Eyebrow - Osmotic

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Eyelids

In many animals, including humans, eyelids wipe the eye and prevent the eyes from dehydration. They spread tear fluid on the eyes, which contains substances which help fight bacterial infection as part of the immune system.

Related Topics:
Eyelid - Bacterial infection - Immune system

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Some aquatic animals have a second eyelid in each eye which refracts the light and helps them see clearly both above water and below it.

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Eyelashes

In many animals, including humans, eyelashes prevent fine particles from entering the eye. Fine particles can be bacteria, but also simple dust which can cause irritation of the eye, and lead to tears and subsequent blurred vision.

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