Anatomy & Physiology of the eye , a ReviewDr. Chin Kel Vin ,Department of Ophthalmology ,Hospital Queen Elizabeth.

Anatomy of the eye

Can be divided into 2 segments :-Anterior segment in front of lens.Posterior segment behind the lens.

There are grossly 3 layers of specialized tissues in the posterior segment :-Sclera outermost layerChoroid intermediate layerRetina innermost layer

There are 6 muscles controlling the extraocular movement :-Superior rectus , Medial rectus , Inferior rectus , Inferior Oblique (CN3)Superior Oblique (CN4)Lateral Rectus (CN6)

Vitreous Body

fills the eyeball behind the lens.

Occupies about 4/5 of the eyeball and lies between the lens and the retina.

Consist of a colorless , transparent gel which is 98% water.

It has a refractive index of 1.33 which is nearly the same as that of aqueous humour.

Functions :1) transmit light.2) contributes to the dioptric power of the eye. 3) supports the posterior part of the lens

Retina

Is a highly specialized sensory tissue that forms as direct extension of the central nervous system in embryologic development.

Divided into 2 different layers :-1)Outer retinal pigment epithelium 2) Inner neurosensory layer

- functions to convert light energy into a complex series of impulses that the brain perceives as vision.