The Eye Globe

CHAPTER 6.

THE EYEGLOBE

THE FOLLOWING ASPECTS WILL BE COVERED BY THE END OF THIS

CHAPTER:

• 1. EYEGLOBE – GENERALITIES, MEASUREMETS
• 2. EYEGLOBE -LAYERS AND CONTENTS
• 1. EYEGLOBE – GENERALITIES , MEASUREMENTS.
• The eye is a highly specialized organ of photoreception , the process by
• These changes result in nerve action potentials , which are subsequently
• relayed to the optic nerve and then to the brain , where the information is
• Processed and consciously appreciated as vision.
• All the other structures in the eye are secondary to this basic physiologic
• although they may be part of the system necessary for focusing and
• transmitting the light onto the retina, for example cornea, lens, iris, and
• ciliary body , or they may be necessary for nourishing and supporting the
• tissues of the eye, for example the choroid, aqueous outflow system, and
• lacrimal apparatus.
• Occupies only one-fifth of the orbital cavity.
• The eyeball
• The adult human eye averages 24mm in diameter.
• The normal anteroposterior diameter varies between 21 and 26mm. This
• measurement is characteristically smaller in hypermetropia and larger in
• myopia.
• 38
• Rim of bone
• Extraocular muscle
• Iris
• Cornea
• Pupil
• Lens
• plic nerv
• Retina
• Extraocular muscle
• Fig. 6.1. Schematic representation of the Eyeglobe in the orbit.
• 2. EYEGLOBE -LAYERS AND CONTENTS.
• The eye is made up of three basic layers or coats and three different
• contents.
• The three basic layers are :
• e the outer fibrous, protective coat (cornea, sclera);
• e the middle vascular uveal tract (iris, ciliary body, choroid);
• e the inner neural layer (retina).
• The coats surround the three different contents :
• e the crystalline lens;
• e the aqueous humour;
• e the vitreous humour
• 39
• Fig. 6.2. Diagram representing the layers and contents of the eyeglobe.

40