"
messages[2]="Superior orbital septum: a collagenous curtain connecting frontal bone and upper lid tarsus. It acts as a barrier to inflammation spreading backward from the eyelid.
"
messages[3]="Superior tarsus: a connective tissue plate that contains sebaceous glands providing an oily base for the tear film. The tarsus gives firmness to the distal portion of the upper lid. Foreign bodies that fly onto the surface of the eye often find their way into a slight depression on the conjunctival surface of the tarsus. In order to remove them, one must exposure this surface by everting the upper lid, using the upper border of the tarsus as the fulcrum.
"
messages[4]="Cornea: the transparent anterior refracting surface of the eye. It accounts for 2/3 of the refracting power of the eye (the lens has the remaining 1/3). There are three main layers: an outer epithelium, a collagenous stroma, and an inner endothelium. If abraded or infected, the epithelium will regenerate without harming vision. But if the stroma is damaged, a scar forms to distort and opacify the cornea and reduce vision. This is why epithelial damage must be managed quickly and correctly. The endothelium has a metabolic pump that keeps water out of the cornea in order to maintain transparency. When it is damaged, the cornea becomes edematous and loses transparency.
"
messages[5]="Pupil: the opening between the anterior and posterior chambers of the eye. Its size is controlled by constriction and dilation of the iris.
"
messages[6]="Lens: a largely proteinaceous structure suspended by zonular ligaments. It accounts for 1/3 of the refracting power of the eye (the cornea accounts for 2/3). The anterior lens has dividing cells that migrate toward the center and lose their nuclei. Advancing age and metabolic, inflammatory, or traumatic insults bring about degeneration of lens protein and opacification of the lens (cataract). Fortunately, the lens can be removed surgically without harming the eye and replaced with a clear artificial lens implanted in the same area.
"
messages[7]="Iris: the diaphragm that controls the amount of light entering the eye. It has two layers, a posterior pigment epithelium and an anterior stroma made of collagen, muscle and pigment cells. The more pigment in these stromal cells, the darker the iris. There are two muscles: a circumferential parasympathetically-controlled sphincter that constricts the pupil and a radial sympathetically-controlled muscle that dilates it.
"
messages[8]="Ciliary body: consists of two portions, a secretory epithelium and a muscle. The secretory epithelium manufactures aqueous, a nutrient fluid. The muscle's function is to control accommodation, a change in the refracting power of the lens. When the ciliary muscle contracts, the zonules loosen, and the lens assumes a more rounded shape. This \"rounding up\" gives the lens more refracting power and allows the eye to focus objects viewed at reading distance. Accommodation is gradually lost with aging (\"presbyopia\") as the lens stiffens and cannot react to loosening of the zonules.
"
messages[9]="Inferior tarsus: like the superior tarsus, but much smaller. Foreign bodies do not lodge here.
"
messages[10]="Inferior orbital septum: analogous to the superior orbital septum.
"
messages[11]="Maxilla: forms part of the floor of the orbit.
"
messages[12]="Frontal lobe: the most anterior and basal part of this brain lobe overlies the orbit.
"
messages[13]="Vitreous cavity: is filled with the vitreous humor, a transparent gel that maintains structure of the globe. It is made up of hyaluronic acid, collagen fibers, and a dilute salt water solution. The collagen is thickest in it peripheral portion, the vitreous cortex, which has firm attachments to the anterior retina and the border of the optic disc. With aging (or inflammation, high myopia, and trauma), the vitreous degenerates into lakes of water that place stress on its attachments to the retina. Eventually, the vitreous detaches itself from the optic disc, leaving a floater. If the peripheral vitreous cortex detaches from the retina, it may tear a hole in the retina. If fluid seeps under the hole, the retina may detach, and vision is lost. The retina must be emergently reattached surgically to preserve vision.
"
messages[14]="Levator palpebrae superioris muscle: controls elevation of the upper eyelid. Innervated by the superior division of the third cranial nerve.
"
messages[15]="Superior rectus muscle: one of six extraocular muscles, one of four rectus muscles, it elevates the eyeball. Controlled by the superior division of the third cranial nerve.
"
messages[16]="Orbital fat: supplies cushioning for the eyeball and its appendages.
"
messages[17]="Optic nerve: contains the retinal ganglion cell axons that are travelling to the optic chiasm and on to the lateral geniculate body.
"
messages[18]="Retina: the neural inner layer of the posterior part of the eye. It has a nutrient retinal pigment epithelial outer portion and a sensory inner portion.
"
messages[19]="Choroid: the vascular nutrient layer of the outer retina.
"
messages[20]="Sclera: the collagenous outer wall of the eyeball. Its outermost portion, called the episclera, has a rich vascular network. It is here that bilirubin accumulates to stain the superficial sclera yellow (\"icterus\"). The sclera becomes inflamed in connective tissue diseases, usually forming a nodule with a tangle of hyperemic episcleral and conjunctival vessels. The episclera is covered by the conjunctiva, a vascular mucous membrane.
"
messages[21]="Inferior rectus muscle: one of the six extraocular muscles, one of four rectus muscles, it depresses the eyeball. Controlled by the inferior division of the third cranial nerve.
"
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