Vascular layer

• structures in uvea


  choroid

  ciliary body

  iris
• uvea anatomy

  
• iris - what type of muscle is this? it is the anterior extension of...

  -thin pigmented muscle

  -anterior extension of uveal tract

  -extends from iris root to iris margin
• pupil - this is the central...

  central aperture of iris
• pupil anteriorly lies on..

  lies on anterior lens surface surrounded by aqueous humour
• posteriorly

  central portion of iris is in contact with lens
• functions of iris

  -control retinal illumination

  -depth of focus

  -reduction in optical aberration
• control of retinal illumination happens through response to.... and also immediate facilitation of...

  -response to change in lighting maintains constant retinal illumination

  -immediate facilitation of light or dark adaption with abrupt changes in lighting
• depth of focus - what effect is produced to reduce refract error and to increase depth of focus?

  Meiosis during near effort produces pinhole effect, reducing refractive error and increasing depth of focus
• reduction in optical aberration minimises...

  -minimizes optical aberrations in the lens by limiting the light rays entering the eye

  -glare and aberrations commonly occur with a large pupil in darkness or after mydriasis
• further from axis

  further the light beams from the focal point
• iris diameter

  smaller iris diameter = clearer image and better VA
• iris topography

  
• ciliary zone, what type of area is this?

  -inner smooth area

  -middle furrowed area

  -marginal cribriform area
• pupillary zone, beings at.. has a connecting...

  -begins at margin of pupil/pupillary ruff

  -connecting crest

  -deep radial slits/ridges
• 1) anterior border layer -thin discontinuous condensed _____ _____

  -composed of ______ _____ and _______

  -contains _________

  -absent in area of the crypt

  -thin discontinuous condensed anterior stroma

  -composed of collagen fibrils and fibroblasts

  -contains melanocytes

  -absent in area of the crypt

  
• 2) stroma - - loose pigmented highly ________ tissue

  -contains pigmented and non pigmented cells muscles, ______ _____ and ______ ______

  -loose pigmented highly vascular tissue

  -contains pigmented and non pigmented cells muscles, collagen fibrils and ground substance

  
• pigmented cells stroma contains

  melanocytes and clump cell
• non pigmented cells stroma contains

  fibroblast lymphocyte macrophage mast cells
• why do we have diff eye colours

  determined by the character of melanin and amount of pigmentation not the number of melanocytes
• iris naevus is..

  proliferation of uveal melanocytic cells

  
• iris melanoma is...

  malignant transformation of iris neavus

  
• iris muscles

  sphincter and dilator
• sphincter muscle - this is in what zone? what is its diameter and thickness? It is supplied by what nerve?

  -pupillary zone

  -parallel to the pupillary margin

  -measure 0.75mm in diameter and has thickness of 0.1-1.7mm

  -contractions causes constriction (miosis)

  -supplied by parasympathetic nerve

  
• miotic, what type of nerves and what type of activation/relaxation

  -Short ciliary nerves

  -Parasympathetic activation

  -Sympathetic relaxation
• dilator muscle - thickness, location, contraction cause, nerve supply

  -4ųm in thickness

  -located in ciliary zone •

  Oriented radially from iris root toward the pupil

  -contraction cause - dilatation of pupil (mydriasis)

  -supplied by sympathetic nerve

  
• how to remember miotic

  little word little pupil
• how to remeber mydriatic

  big word big pupil
• mydriatic - what type of nerves and what type of activation/relaxation

  -long ciliary nerves

  -parasympathetic relaxation

  -sympathetic activation
• problems with wide pupil/contracted dilator

  can block channel of schlemm
• direct light reflex

  shining light to an eye cause causes pupillary constriction same
• consensual light reflex

  shining light to one eye cause pupillary constriction of other eye
• cause for pupillary light response

  amount of light on the retina
• type of control of pupil size

  autonomic
• type of response for pupil size

  bilateral
• 3) anterior epithelium and dilator muscle is composed of _____ cells

  composed of unique myoepithelial cells
• 4) posterior epithelium -single layer of heavily pigmented simple __________ cells

  -at posterior, continuous with inner non-pigmented epithelial layer of ______ ________

  -curled to anterior surface at pupil margin - pupillary ruff

  -single layer of heavily pigmented simple columnar cells

  -at posterior, continuous with inner non-pigmented epithelial layer of ciliary body

  -curled to anterior surface at pupil margin - pupillary ruff
• iris blood supply - -at the ciliary processes the long posterior ciliary arteries bifurcate and form a series of ______________, which in turn form....

  -________ _______ around the external circumference of the iris (major arterial circle of the iris)

  -minor circle of the iris proximal to the pupil

  -at the ciliary processes the long posterior ciliary arteries bifurcate and form a series of anastomoses, which in turn form....

  -arterial ring around the external circumference of the iris (major arterial circle of the iris)

  -minor circle of the iris proximal to the pupil

  
• ciliary body topography


  -xtends from the posterior limit of limbus ( scleral spur and iris root) to ora serrata -triangular shape in cross section - base facing anterior chamber and apex at ora serrata
• dimensions of ciliary body

  - 7mm wide temporally

  - 6mm nasally (from limbus)