Fibrous layer

The fibrous layer of the eyeball (Latin: tunica fibrosa bulbi) is the outermost layer of the eyeball. The fibrous layer consists of the sclera - the largest posterior part, white in colour, and the cornea - the anterior part of the fibrous layer, a transparent plate. The sclera and the cornea are continuous with each other.

The sclera can be further divided into three layers:

  • Episclera
  • Scleral stroma
  • Lamina fusca

The sclera acts as a barrier for the eye components and protects those from mechanical trauma. The rigid structure of the sclera is the reason why the eyeball can maintain its shape and keep all the structures in place.

The cornea is divided into five layers:

  • The stratified corneal epithelium
  • The Bowman's membrane
  • The corneal stroma
  • The Descemet's membrane
  • The corneal endothelium

The cornea participates in the refraction of light. The cornea has the most considerable refractive power, and its refractive index is different from the refractive index of the air.