Published on October 28, 2013
EYEBALL Chair Person: Dr. R.D. Virupaxi Presenter: Dr. Kapil Amgain
Scheme of Presentation • • • • • Introduction Structure Blood supply Nerve supply Applied Anatomy
• The organ of sight • Occupies the ant.1/3 of the orbital cavity • Embedded in fat, separated by a membranous sac, the fascia bulbi. • Eyeball closely resembles the Camera Introduction
• Two poles • Two axes • Eqator: an imaginary line arround the eye ball equidistance from the two poles. • Meridian: an imaginary plane from pole to pole and cutting the equator at the right angle.
Concentric coats/tunics of eyeball • Outer fibrous coat: Sclera and Cornea • Middle vascular coat: Choroid, Ciliary Body and Iris • Inner nervous coat: Retina
Structure piercing the sclera • Optic nerve • Post.ciliary vessel and nerve • Venae vorticosae • Ant ciliary artey
Cornea • Structure
Histology of the cornea
Choroid • A thin pigmented layer which separates the post. part of the sclera from the retina.
Histology of the choroid
Ciliary body • A thickened part of uveal tract lying just post.to the corneal limbus. • Pars plana (ciliary ring) • Pars plicata
Iris • It resembles the diaphrgm of camera
Inner coat or Retina • It is the thin, delicate inner layer of the eyeball • Continuous posteriorly with the optic nerve
Histology of the retina
Aqueous humour Composition • Amino acids transported by cilliary muscles. • 98% water • Electrolytes • Ascorbic acid • Glutathione
Vitreous humour/body • The vitreous is the transparent, colourless, gelatinous mass that fills the space between the lens of the eye and the retina lining the back of the eye. • It is produced by cells in the non-pigmented portion of the ciliary body deriven from embryonic mesenchyme cells which then degenerate after birth.
Vitreous Body • Its composition is similar to the cornea, but contains very few cells (mostly phagocytes which remove unwanted cellular debris in the visual field, as well as the hyalocytes of the surface of the vitreous, which reprocess the hyaluronic acid), • • • • • • • No blood vessels. Water = 98-99% of its volume (75% in the cornea) Salts, sugars, vitrosin (a type of collagen), a network of collagen type II fibres Glycosaminoglycan Hyaluronic acid and many proteins in micro amounts. The vitreous body has a viscosity two to four times that of pure water, giving it a gelatinous consistency. It also has a refractive index of 1.336
Lens • The crystalline lens is a transparent, biconvex structure in the eye that, along with the cornea, helps to refract light to be focused on the retina. • The lens, by changing shape, functions to change the focal distance of the eye so that it can focus on objects at various distances, thus allowing a sharp real image of the object of interest to be formed on the retina
Histology of the lens
Movement of eyeball • • • • • • E: D: MR: LR: In: Ex:
Action of extraoccular Muscle
Development of eyeball
Light Reflex • Shining light into one eye causes constriction of iris muscles on both sides
Accommodation Reflex • Directing eyes from a distant object to a near object causes constriction of iris muscles on both sides.
Consensual light reflex
Blood Supply of eyeball
Blood supply of eyeball • Ophthamic artery
Nerve supply • Sclera: • Cornea:ophthalmic nerve through long ciliary nerve which form 4 plexus as they reach the cornea (anular, proprial, subepithelial and intraepithelial • Choroid: • Ciliary muscle: parasympathetic nerve • Iris:
Applied Anatomy • • • • • Conjunctivitis Glaucoma Corneal opacities Corneal grafting Jaundice can be visualized on the bulbar conjuctive • Myopia • Hypermetropia • Presbyopia/Astigmatism
Closed angle glaucoma
Open-Angle Glaucoma • Primary OpenAngle Glaucoma: The drainage angle is open within the eye, but for unknown reasons, does not allow fluid to drain.
Glaucoma: Open vs Closed angle
Papiloedema & Papillitis • Cupping of optic disc • Atrophy of optic nerve due to chronic pressure
Myopia vs Hypermetropia
Calcification Inhibitors in CKD and Dialysis Patients
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