EYE

• Eye


  Organ of vision, Composed of Eyeball and Optic Nerve
• Orbit


  Bony structure that contains the eyeball and accessory visual structures
• Orbital region


  The area of the face overlying the orbit and eyeball, Includes Upper and lower eyelids, Lacrimal apparatus
• WALLS OF THE ORBIT

  Orbit is a pyramid, Bilateral bony cavities resemble a hollow, quadrangular pyramid
• Bones of the Orbit

  • Frontal
  • Maxilla
  • Zygomatic
  • Sphenoid
  • Ethmoid
  • Lacrimal
  • Palatine
• Orbital Rim


  Has contributions from different bones to form the orbital rim
• Components of the Orbit

  • Roof (Superior Wall): Frontal Bone, Lesser Wing of the Sphenoid Bone, Floor (Inferior Wall): Maxillary Bone, Palatine Bone, Medial Wall: Ethmoid Bone, Maxillary Bone, Lacrimal Bone, Sphenoid Bone, Lateral Wall: Zygomatic Bone, Greater Wing of Sphenoid Bone, Apex: Optic Foramen, Base: Orbital Rim
• ANTERIOR ACCESSORY VISUAL STRUCTURES

  Structures that protected the eyeball: Eyelids, Extraocular muscles, Nerves and vessels, Orbital fascia, Mucous membrane (conjunctiva)
• Structures of the eye and orbit

  • Eyelids
  • Extraocular muscles
  • Nerves and vessels
  • Orbital fascia
  • Mucous membrane (conjunctiva)
• Eyelids cover the eyeballs and protect the eyes from entry and excessive light
• Eyelids keep the cornea moist by spreading the lacrimal fluid
• Covering of the eyelids

  • Externally: Thin Skin
  • Internally: Palpebral Conjunctiva
  • The Palpebral Conjunctiva is continuous with the Bulbar Conjunctiva
• Palpebral Conjunctiva


  • Transparent mucous membrane
  • Continuous with the Bulbar Conjunctiva
  • Creates continuous recesses (pockets)
• Bulbar Conjunctiva


  • Transparent and loosely attached to the sclera
  • Contains small, visible blood vessels
  • Reflects in the eyeball
• Continuous recesses created by the Palpebral Conjunctiva

  • Superior Conjunctival Fornix
  • Inferior Conjunctival Fornix
• Spaces created by the Palpebral and Bulbar Conjunctiva

  • Conjunctival sac
  • Superior and Inferior Conjunctival Sac
• Palpebral Fissure


  • Line when eyes are closed
  • Space between the eyelids when eyes are opened and closed
• Tarsal Glands


  • Embedded in the tarsi
  • Produce a lipid secretion to lubricate the edges of the eyelids and prevent sticking together
• Eyelashes

  • Ciliary Glands: sebaceous glands associated with the eyelashes
  • Medial and Lateral Palpebral Commissures: define the medial and lateral angles of the eye
• Flow of tears

  1. Lacrimal Gland

  2. Lacrimal Duct

  3. Superior/Inferior Lacrimal Canal

  4. Lacrimal Sac

  5. Nasolacrimal duct

  6. Nasal Cavity
• The Lacrimal Apparatus includes the Lacrimal Gland that secretes lacrimal fluid
• The Nasolacrimal duct conveys the lacrimal fluid to the inferior nasal meatus
• The Eyeball is suspended by 6 extrinsic muscles and is approximately 25mm in diameter
• EYEBALL is suspended by 6 extrinsic muscles
• EYEBALL is approximately 25mm in diameter
• Posterior view of eyeball
• LAYERS of the eyeball

  Fibrous Layer, Vascular layer, Inner layer (Retina)
• FIBROUS LAYER


  • Provides shape and resistance to the eyeball
  • Has 2 layers: sclera, cornea
• Cornea

  • Covers anterior
  • Transparent part of the fibrous layer
  • Completely avascular
  • Gets nutrients from capillary beds, lacrimal fluid, and aqueous humor
• Sclera

  • Anteriorly seen as the white part of the eye
  • Relatively avascular
  • Tough and thick part of the fibrous layer
  • Provides attachment for extrinsic muscles of the eye
• VASCULAR LAYER


  • Also called uvea or uveal tract
  • Composed of Choroid, Ciliary body, Iris
• Choroid


  • Largest part of the layer
  • Larger vessels located externally, smaller vessels internally
• Ciliary body

  • Connects choroid to the circumference of the iris
  • Provides attachment for the lens
  • Controls the focus of the lens
  • Secretes aqueous humor
• Iris

  • Anterior surface of the lens
  • Controls the pupil
  • Pupil: space between the iris transmitting light to the eyeball
  • Involuntary muscles control pupil size
• Parasympathetic


  Sphincter pupillae constricts or contracts pupil in bright light
• Sympathetic

  Dilator pupillae dilates pupil in low light
• INNER LAYER / RETINA


  • The sensory neural layer
  • Optic part, Non-visual retina
• Optic part

  • Neural layer - light receptive layer
  • Pigmented layer - reinforces light absorbing property of the choroid
• Non-visual retina


  • Thinner yellow part
• Fundus of the eyeball is the internal aspect of the posterior part of the eyeball where light focuses