This document describes the anatomy and biochemistry of various components of the eye. It discusses the cornea, lens, vitreous humour, aqueous humour, retina and tear film. The cornea consists of five layers and is mostly water. The lens is a transparent biconvex structure behind the iris that is high in water and proteins. The vitreous humour is a gel-like fluid behind the lens composed mainly of water, collagen and carbohydrates. The aqueous humour maintains intraocular pressure and contains mostly water and small amounts of protein. The retina converts light signals into nerve signals that are sent to the brain via the optic nerve.

1. EYE AND ITS COMPONENTS
By: Sunny prajapati
B.optometry, 2nd sem

3. CORNEA
Transparent, avascular and watch glass like structure
Covers the anterior 1/6 th part of the eye
Refractive index and power: 1.37, +43 D
The layers of cornea are
1.Epithelium
2.Bowman’s membrane
3.Stroma
4.Descements membrane
5.Endothelium

4. Biochemistry of Cornea
cornea consists 80% of water and 20% solids.
1. Epithelium
70% of water
protein,lipids, enzymes necessary for glycolysis and Kreb's cycle
ATP, glycogen, glucathione and ascorbic acid, acetycholine,
electrolytes.
2. Bowman's membrane:
not a true elastic membrane but simply a condensed superficial part of
the stroma.
3. Stroma
70 – 80% water
20-25% extracellular collagen, soluble proteins, proteoglycans,
enzymes, matrix metalloproteinases, electrolytes

5. 4. Descemet’s membrane
Made up of collagen and glycoproteins.
Does not contain GAG.
5. Endothelium
Delicate nature of single cell layer
It has not been possible to analyse its BIOCHEMISTRY

6. KERATOCONUS
degenerative disorder of the eye in which structural
changes within the cornea cause it to thin and change
to a more conical shape than the more normal gradual
curve
Keratoconus is caused genetically or environmental
causes such as trauma, oxidative stress, allergies
vision, with multiple images, streaking and
sensitivity to light

7. TEAR FILM
Tear fluid is clear, salty,slightly alkaline and watery.
Thickness: 4 to 8 µm
Volume: 7µl
Rate of tear secretion: 1.2 µl per min
Refractive index: 1.357
pH of tear: 7.3 to 7.7

8. BIOCHEMISTRY OF TEAR FILM
 Tear constitutes of the 98.2% of water
 The total protein content strongly depends on the method
of collection of tears.
 Proteins found in human tears :
Protein Normal undistribut
ed state (%)
Reflex Tears (%)
Albumin 58.2 20.2
Globulin 23.9 56.9
Lysozyme 17.9 22.9

9. CRYSTALLINE LENS
Clear, transparent, biconvex, flexible structure
Behind the iris & pupil
Refractive index – 1.39
Colour changes with age.
Refractive power is about 16-17 D

10. BIOCHEMISTRY OF LENS
Main constituents of the lens are water and proteins.
Water constitutes of 65% of lens wet weight.
Protein: Protein content of the lens higher then that of any
other organ of the body. Protein maintenance transparency
of the lens.
Amino acids :Two groups of the amino acids are present in
the lens:
1.Proteogenic group
2.Non – proteogenic group

11.  Carbohydrates :
 Carbohydrate metabolism of the lens is highly active and
complex.
 Derivatives of sugar found in lens are sorbitol, inositol,
ascorbic acid.
 The total lipids of human lens amount to about 2.5% wet
weight.

12. VITREOUS HUMOUR
Inert, transparent, colourless, gel-like fluid.
Helps to maintain the shape of the eye.
Located behind the lens & in front of the retina.
Largest and simplest connective tissue present as single
piece in human body.

13. BIOCHEMISTRY OF VITREOUS HUMOUR
Composed of three major components:
Water
Collagen fibres
Glycoaminoglycans
Water forms 99% of the wet weight of the vitreous.
Vitreous water is replaced is every 10-15 minutes.
The vitreous gel contains glucose, fructose, galactose.
The concentration of ascorbic acid is higher in the vitreous then that of
the plasma.
Vitreous contains calcium, chloride, lactic acid etc.

14. AQUEOUS HUMOUR
 transparent, gelatinous fluid.
 Maintenance of intraocular pressure
 Ciliary body is the site of aqueous production.
 found in anterior segment of the eye.

15. BIOCHEMISTRY OF AQUEOUS HUMOUR
 It constitutes of about 99.9 % of water.
 Protein in the aqueous humour is only 5-16 mg/100ml.
 Inulin and steroid hormones are also present and enter the
aqueous humour by simple diffusion.
 Amino acids.

16. RETINA
 Acts like the film in a camera to create an image
 Consists of a specialized layer of cells
 Converts light signals into nerve signal then send these
signals to the optic nerve
 Optic nerve carries the signals to the brain
 The brain helps process the image

18. THANK YOU..