The Eyes - Anaphy

• The eye is surrounded and protected by the bony structure called orbit.
• External layer of the eye:

  • Sclera
  • Cornea
• Cornea - transparent domelike structure; attracts light to enter the eyes; light is the requirement to vision; without light, there’s no vision
• Sclera - outer & toughest layer; colored white
• Middle Layer of the Eye:

  • Choroid
  • Ciliary Body
  • Iris
• Choroid - contains many blood vessels and supplies nutrients to the retina
• Ciliary body - secretes aqueous humor that helps give the eye its shape
• Iris - colored portion of the eye. It has a central circular opening called the pupil.
• Pupil - constricts & dilates based on illuminated (light)
• Choroid - middle layer; brown because it is highly vasculated; bleeds heavily when injured
• Innermost layer of the Eye:

  • Retina
• Retina - visual receptive layer where images are converted into nerve impulses
• Retina - contains blood vessels and photoreceptors
• Cons - receptors for day/bright vision (iNcreased light), photoreceptor cells, located in the retina
• Rods - receptors for dim/night vision (Decreased light), photoreceptor cells, located in the retina
• Rods - receptors for peripheral vision
• Cons - receptors for central vision
• Vitreous Humor - a jelly-like strucutre found inside the eye; it maintains the normal shape of the eye; sphere
• Macula lutea - contains the fovea centralis which is the center for acute vision
• Aqueous Humor - liquid; maintains normal pressure of the eyes (IOP)
• Aqueous Humor

  NORMAL: 10-21 mm Hg
• Aqueous Humor drains into the canal of Schlemm and out into the systemic circulation.
• Aqueous Humor fills the anterior (in front of the iris) and posterior (behind the iris) chambers.
• Lens - bend rays of light so that light falls on the retina.
• Pupil - controls the amount of light that enters the eye and reaches the retina.
• Darkness produces dilatation (mydriasis); light produces constriction (miosis)
• Conjunctiva - clear membrane that protects the eye; covers the inside of eyelid & the sclera (white of the eye)
• Lacrimal gland - produces tears which are drained into the lacrimal duct and sac.
• Cranial Nerves that control the Eyes: II,  III, IV, VI
• Lens - refraction or accommodation; adjustment of it depending on how far/near or big/small is a suject