Is conjunctiva and sclera same?

The conjunctiva contributes to the tear film and protects the eye from foreign objects and infection. The sclera is the thick white sphere of dense connective tissue that encloses the eye and maintains its shape.

Is the sclera refractive?

The sclera is essentially acellular, containing only a few fibroblasts and non-branching traversing vessels. Recent studies have shown that there are some contractile fibroblasts (myofibroblasts) in the sclera and choroid that may have a role in refractive properties of the eye.

How do I know if I have sclera?

It is thickest in the area surrounding the optic nerve. The sclera is made up of three divisions: the episclera, loose connective tissue, immediately beneath the conjunctiva; sclera proper, the dense white tissue that gives the area its color; and the lamina fusca, the innermost zone made up of elastic fibers.

Is the sclera white or clear?

In the elderly, fatty deposits on the sclera can make it appear slightly yellow. People with dark skin can have naturally darkened sclerae, the result of melanin pigmentation. The human eye is relatively rare for having a pale sclera (relative to the iris)….

Where does the white part of the sclera come from?

In humans, the whole sclera is white, contrasting with the coloured iris, but in other mammals the visible part of the sclera matches the colour of the iris, so the white part does not normally show. In the development of the embryo, the sclera is derived from the neural crest.

How does the sclera protect the eyes from damage?

The tough, fibrous nature of the sclera also protects the eye from serious damage — such as laceration or rupture — from external trauma. The sclera also provides a sturdy attachment for the extraocular muscles that control the movement of the eyes. Here are a few conditions that can affect the sclera: Scleral icterus (yellow eyes).

What does it mean when your sclera is swollen?

When the sclera is swollen, red, tender, or painful (called inflammation), it is called scleritis. It is common for people with scleritis to have another disease, like rheumatoid arthritis or other autoimmune disease. This underlying disease causes many of the symptoms of scleritis. There are two main types of scleritis:

Why are the four layers of the sclera opaque?

From outer to innermost, the four layers of the sclera are: The sclera is opaque due to the irregularity of the Type I collagen fibers, as opposed to the near-uniform thickness and parallel arrangement of the corneal collagen.