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The fibrous tunic, also known as the tunica fibrosa oculi, is the outer layer of the eyeball consisting of the cornea and sclera. [4] The sclera gives the eye most of its white color. It consists of dense connective tissue filled with the protein collagen to both protect the inner components of the eye and maintain its shape. [5]
In order, along the optic axis, the optical components consist of a first lens (the cornea—the clear part of the eye) that accounts for most of the optical power of the eye and accomplishes most of the focusing of light from the outside world; then an aperture (the pupil) in a diaphragm (the iris—the coloured part of the eye) that controls ...
Evisceration – removal of the iris, lens, and internal eye contents, but with the sclera and attached extraocular muscles left behind; Enucleation of the eye – removal of the eyeball, but with the eyelids and adjacent structures of the eye socket remaining. An intraocular tumor excision requires an enucleation, not an evisceration.
The globe of the eye, or bulbus oculi, is the frontmost sensory organ of the human ocular system, going from the cornea at the front, to the anterior part of the optic nerve at the back.
The sclera can be seen above the cornea, and further upgaze increases the distance between the eyelids and irises. Causes Upper dorsal midbrain supranuclear lesions such as Parinaud's syndrome, 'top of the basilar syndrome', midbrain infarction, neurodegeneration or tumour, multiple sclerosis, encephalitis, and Miller-Fisher syndrome.
The thickness of the sclera varies from 1 mm at the posterior pole to 0.3 mm just behind the insertions of the four rectus muscles. The sclera's blood vessels are mainly on the surface. Along with the vessels of the conjunctiva (which is a thin layer covering the sclera), those in the episclera render the inflamed eye bright red. [6]
Jaundice, also known as icterus, is a yellowish or greenish pigmentation of the skin and sclera due to high bilirubin levels. [3] [6] Jaundice in adults is typically a sign indicating the presence of underlying diseases involving abnormal heme metabolism, liver dysfunction, or biliary-tract obstruction. [7]
It is called RB for short. Check photographs, normal healthy eyes would have the red eye reflex, but a white/yellow dot instead of the red eye reflex can indicate a tumor or some other kind of eye disease. Any photos of a child/children which have a white/yellow dot instead of the red eye reflex should be evaluated by an eye doctor.