The Sclera

• What are the main topics covered in the agenda?

  Gross anatomy, microanatomy, functions, special regions
• What is the purpose of recognizing, listing, and describing structures?

  To understand anatomical and physiological varieties
• What are the layers of the eyeball?

  • Fibrous layer: Sclera, limbus, cornea
  • Vascular layer: Iris, ciliary body, choroid
  • Nervous layer: Pigment layer, neural layer
• What is the primary function of the sclera?

  Protection and maintenance of eyeball shape
• What does the sclera form in the eye?

  Posterior 5/6 of the connective tissue coat
• What covers the sclera anteriorly?

  Conjunctiva

  
• What is the relationship between the sclera and the choroid?

  The inner surface of the sclera contacts the choroid
• What are the special regions of the sclera?

  • Scleral sulcus: Indentation near the limbus
  • Sclera spur: Circular flange deep to Schlemm’s canal
  • Schlemm’s canal: Ring-shaped vessel encircling the cornea
  • Lamina cribrosa: Sieve-like structure for optic nerve
  • Scleral apertures: Three sets of apertures

  
• What is the scleral sulcus?

  Indentation on the inner surface near the limbus
• What is the sclera spur?

  Circular flange deep to Schlemm’s canal
• What is Schlemm’s canal?

  Ring-shaped vessel encircling the cornea

  
• What is the lamina cribrosa?

  Sieve-like sclera for optic nerve fibers
• What is the significance of the lamina cribrosa's structure?

  It allows optic nerve fibers to pass through
• What are the histologic features of the sclera?

  Episclera, scleral stroma, lamina fusca
• What is the episclera?

  Outermost layer of loose connective tissue
• How does the scleral stroma contribute to the eye's structure?

  Provides strength and flexibility to the eye
• What is the composition of the scleral stroma?

  Thick, dense connective tissue with collagen
• How does the arrangement of collagen fibrils in the sclera affect its properties?

  Irregular arrangement contributes to strength
• What affects the opacity of the sclera?

  Number of GAGs and water content
• What is the lamina fusca?

  Innermost layer with melanocytes and grooves
• What separates the lamina fusca from the choroid?

  The perichoroidal space
• What is the blood supply to the sclera?

  • Anterior ciliary arteries supply anterior sclera
  • Conjunctival vessels: superficial and mobile
  • Superficial episcleral plexus: straight and radial
  • Deep vascular plexus: immobile in superficial sclera
  • Posterior: branches from long and short posterior ciliary arteries
• What happens in episcleritis?

  Maximal congestion occurs in the vascular plexus
• How can scleritis be identified during examination?

  It often has a purplish hue
• What is the scleral foramen?

  Opening for the optic nerve in the lamina cribrosa
• How far is the lamina cribrosa from the posterior pole?

  3 mm medial, 1 mm above
• What is the significance of the scleral apertures?

  They allow passage for blood vessels and nerves
• What are the three sets of scleral apertures?

  Anterior, middle, posterior
• What is the role of the scleral blood supply?

  To nourish the sclera and surrounding tissues
• What type of collagen is found in the scleral stroma?

  Collagen type I and III
• How does the sclera maintain its shape?

  Through the strength and firmness of its structure
• How does the sclera's structure contribute to its function?

  Its dense connective tissue provides protection