Anatomy and Refractive Media of the Eye

Sonie Umbara, MD

AnatomyEyeball, Orbit & Adnexa

AnatomyEyeball Dimension

Anterior Chamber

Posterior Chamber

Vitreous Cavity

Anatomy

Conjungtiva• Transparent membrane• Richly vascular• Protective

1. Ciliary Body• Part of uvea• Produce aqueous humor• Attached to zonule

Uveal Tract

2. Iris• Part of uvea• Contains blood vessels and connective tissue

3. Choroid

Anatomy3 layers

The Refractive MediaThe media passed by light before reaching the retina

AnatomyPrecorneal Tear Film

• Functions:

• Produce smooth optical surface

• Lubrication

• Oxygen & nutrients diffusion

• Protection

• Layers:

• Lipid layer

• Aqueous layer

• Mucin layer

AnatomyCornea

• Avascular, transparent

• Refractive medium (40-44D)

• Diameter (V:9-11 mm, H:11-12 mm)

• Thickness (central:0,5mm, perifer: 1mm)

Aqueous humour■ Transparent colorless fluid.

■ It fills anterior and posterior chambers of the eye.

■ It is formed continuously by the ciliary epithelium by diffusion and active transport and drained by canal of Schlemm at corneo-scleral junction

■ Rate: 1-2 ul/min

Refractive medium, its

refractive index is 1.33

Nourishment of the avascular

cornea and lens

Keeps the eyes rigid and

maintains its refractory power

Maintains intraocular pressure

Lens

■ It is an elastic biconvex, transparent circular lens.

■ It is about 11 mm in diameter.

■ It is suspended to the ciliary body by the suspensory ligament.

■ It has a refractive power of 20 D during rest, but its power increase during accomodation to near vision

■ 1/3 refractive power of eye

■ It has a refractive index of about 1.40

Vitreous body

■ Refractive medium, its refractive index is 1.34.

■ Supports the retina.

■ Supports the lens.

■ Maintains the spherical shape of the eye.

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