1. (The Photoreceptor System)
THE EYE-VISION
(The Photoreceptor System)

2. Schematic horizontal meridional section of right eye
Optic nerve
Dura
Med. rectus
Ora serrata
Zonula ciliaris
Lamina cribrosa
Fovea
Retina
Choroid
Sclera
Lat. rectus
Ciliary muscle
Limbus
Posterior chamber
Canal of Schelemn
Conjunctiva
Cornea
Anterior
Chamber iris
V.A.
A.P.
P.P.
Vitreous
Ciliary body
Lens

3. ORGAN OF VISION Eyeball Accessory Structure (Adnexa) Layers Fills
T.Fibrosa (External Layer)
T.Vasculosa (Middle Layer)
T. Nervosa (inner Layer)
Sclera
Cornea
Choroid
Ciliary Body
Iris
Retina
Lens
Anterior Chamber
Posterior Chamber
Vitreous Body
Eye Lids
Tears Gland
Muscles

4. TUNICA FIBROSA SCLERA Opaque White
Posterior five sixth of the external layer
Consists of:
Flat Collagen Bundles
Ground Substance
Fibroblasts
Episclera, Tenon’s Space, Tenon’s capsule
Suprachoroidal lamina

5. CORNEA Transparent Colorless Anterior one sixth of the external layer
Consists of 5 layers:
Layer of epithelium
Bowman’s membrane
Substantia Propria
Descement’s membrane
Endothelium
Avasculer structure, receives its metabolizes by:
diffusion from adjacent vessel and from fluid of the anterior chamber

6. A B C D
Conjunctiva
Photomicrographs of a transverse section of cornea. A : The Cornea and conjuctiva seen at low magnification. B : The posterior corneal epithelium – also called endothelium (arrows indicate Descemet’s membrane). C : Conjuntival epithelium D : Anterior corneal epithelium. Note the smooth contour of the surface of this epithelium.

7. Layers of epithelium: Bowman’s membrane: Stratified squamos epithelium
5-6 cells layers
Deepest : columnar
Next : polyhydral
Surface : flat in shape
Bowman’s membrane:
A thin layer
Appears homogenous
Structureless under the light
microscope

8. Descement’s membrane:
Substantia propria
90% of the thickness
Composed:
Collagenous fibrils arranged in lamellae (parallel with the surface)
Mucoid cement
Cells
Descement’s membrane:
Appears homogenous
Fibrous protein of collagen type
Endothelium:
Single layers of cells
Low cuboidal epithelium

9. LIMBUS (Corneoscleral Junction)
Area of transition from transparent collagen bundles of the cornea to the white opaque fibers of the sclera
The corneal epithelium, as it passes over into the limbus, increases in thickness up to ten or more cells
The corneal stroma losses its regular lamellar arrangement
In the stromal layer, irregular endothelium – lined channels, the trabecular mesh work, merge to form the canal of Schlemm

10. Photosensitive retina
Sclera
Limbus
Cornea
Canal of schlemm
Lens
Iris
Zonule
Ora serrata
Posterior chamber
Ciliary body and process
Choroid
Anterior chamber
Vitreous body
Photosensitive retina
Optic papilla
Fovea
Pigment epithelium
Optic nerve
Ciliary muscles
Diagram of the right eye, seen from above, showing the structure of the eye, retina, fovea and ciliary body. Arrows in the anterior chamber show the direction of flow of aqueous humor. An enlarged diagram of the fovea is shown at lower right.
Axons of ganglion cells
Bipolar cells
Rods
Cones

11. Divided into four layers:
TUNICA VASCULOSA
A. CHOROID
Divided into four layers:
The Suprachoroid, lamina suprachoroidea or epichoroid
Consist of lamellae, each lamella: very thin membrane
Vessel layer (stratum vasculosa)
Outer layer : large vessels
Inner layer : medium sized vessels

12. 3. The capillary layer (Lamina Choriocapillaris).
Serves of nutrition for the outer layers of the retina
4. The lamina Vitrea, lamina elastica / basalis, or
membrane of Bruch:
Non cellular membrane
Two layers:
The outer elastic lamellae, very thin
The inner cuticle lamellae, relatively thicker

13. Section through retina, choroid and sclera.
Ch = Choroid;
Ret = Retina;
1 = Suprachoroid;
2 = Vessel layer;
3 = choriocapillaris
4 = Lamina vitrea
5 = Pigment epithelium
6 = layer of rods and
cones
7 = external limiting
membrane
8 = outer nuclear layer
9 = outer plexiform layer
10 = inner nuclear layer
11 = inner plexiform
12 = ganglion cell layer
13 = nerve fiber layer
14 = internal limiting 1
Ch. 2 3 4 5 6 7 8 9 10
Ret. 11 12 13 14

14. B. CILIARY BODY Two zones: The orbiculus ciliaris (Pars Plana)
The posterior two thirds
Appears darkly pigmented
Relatively smooth
The corona ciliaris (Pars Plicata)
The anterior third
Bears some 70 to 80 radially arranged ridges, the ciliary processes

15. Circumlental space
Ciliary processes
Ora serrata
Orbiculus ciliaris
Lens
Zonula fibers
Ora serrata, ciliary body, zonula ciliaris and lens as viewed from behind after removal of the vitreous body

16. IRIS
A thin circular diapraghma
A circular aperture: the pupil
Divides the space between the cornea and the lens into two chambers:
The anterior chamber
The posterior chamber

17. Schematic horizontal meridional section of right eye
Optic nerve
Dura
Med. rectus
Ora serrata
Zonula ciliaris
Lamina cribrosa
Fovea
Retina
Choroid
Sclera
Lat. rectus
Ciliary muscle
Limbus
Posterior chamber
Canal of schelemn
Conjunctiva
Cornea
Anterior
Chamber iris
V.A.
A.P.
P.P.
Vitreous
Ciliary body
Lens

18. Layer of iris is five layers:
Endothelium
A very thin delicate layer
Difficult to demonstrate in sections
Best shown after treatment with silver nitrate

19. The anterior border layer The color of the iris upon:
The thickness of the anterior border layer
And the degree of pigmentation of it cells
In the brown iris:
The layer is thick
The cells heavily pigmented
In the blue iris:
The layer is thin
The cells minimum amount of pigment

20. The vessel’s layer (stroma)
- Consists of a great number of blood vessel
M. Sphincter pupillae:
- In the pupillary zone
Contraction: Reduced the diameter of the pupil
- The dilatator pupillae
Contraction: Dilatation of the pupil
The pigment epithelium

21. Horizontal section through pupillary zone of human iris
Pigment epithelium
Sphincter pupillae
Endothelium
Anterior border layer
Stroma

22. Consists of two portions :
TUNICA NERVOSA
Consists of two portions :
The posterior portion is photosensitive – pars optica retinae
The anterior part is not photosensitive – pars coeca retinae. Constitutes the inner lining of the ciliary body and the posterior part of the iris
The retina forms the pars optica retinae. The scalloped anterior border of the retina is known as the orra serrata.

23. Epithelium
Choroid
Sclera
Photomicrograph of a section of retina in the transition (arrow) between the photosensitive (at left) and blind (at right) parts. This transition is called the ora serrata. Note the pigment epithelium, the choroid and the sclera.

24. RETINA
The retina consists of ten layers ,
except at :
The fovea centralis
The optic disc (optic papillae)
The extreme periphery

25. Photosensitive retina
Sclera
Limbus
Cornea
Canal of schlemm
Lens
Iris
Zonule
Ora serrata
Posterior chamber
Ciliary body and process
Choroid
Anterior chamber
Vitreous body
Photosensitive retina
Optic papilla
Fovea
Pigment epithelium
Optic nerve
Ciliary muscles
Diagram of the right eye, seen from above, showing the structure of the eye, retina, fovea and ciliary body. Arrows in the anterior chamber show the direction of flow of aqueous humor. An enlarged diagram of the fovea is shown at lower right.
Axons of ganglion cells
Bipolar cells
Rods
Cones

26. Development of the retina :
The retina derived from an evagination of the anterior cephalic vesicle or prosencephalon
As this co-called optic vesicle comes into contact with the surface ectoderm, it gradually in vaginates in its central region forming a double – walled optic cup.
In the adult :
The outer wall gives rise to a thin membrane called the pigment epithelium
The inner layer is derived the optical or functioning part of the retina

27. Diagrams of 4 stages in the development of the eye
Lens Vesicle

28. Layer of the RETINA : Pigment epithelium Layers of rods and cones
External limiting membrane
Outer nuclear (or granular) layer
Outer flexiform (or molecular) layer
Inner nuclear (or granular) layer
Inner flexiform (or molecular) layer
Ganglion cell layer
Nerve fiber layer
Internal limiting membrane

29. RETINA, CHOROID AND SCLERA
4. Collagenous fibers
5. Chromatophores
6. Blood vessel
7. Pigment epithelium
8. Rods and cones
9. Outer limiting membrane
10. Outer nuclear layer
11. Outer plexiform layer
12. Inner nuclear layer
13. Inner plexiform layer
14. Ganglion cell layer
15. Nerve fiber layer
16. Inner limiting membrane
1. Sclera
2. Choroid
3. Retina

30. 1. Blood vessels of the choroid
20. Processes of pigment cells extending between rods and cones
21. Cones
22. Rod
23. Outer limiting membrane
24. Nuclei of cones
25. Nuclei of rods
26. Outer processes of Muller’s cells
27. Synapses between horizontal and visual cells
28. Synapses between cones and bipolar cells
29. Bipolar cell
30. Muller’s cell
31. Amacrine cell
32. Synapses between processes of bipolar, amacrine and ganglionic cells
33. Ganglion cell
34. Fiber of optic nerve
35. Horizontal fiber
36. Inner limiting membrane
37. Inner fibers of Muller’s cells
1. Blood vessels of the choroid
2. Chromatophores
3. Pigment cells in the retina
4. Rods
5. Cones
6. Outer limiting membrane
7. Nuclei of cones
8. Nuclei of rods
9. Outer plexiform layer
10. Nuclei of bipolar, horizontal, amacrine and Muller’s cells
11. Inner plexiform layer
12. Ganglion cell layer
13. Muller’s fibers
14. Axons of ganglion cells
15. Inner limiting membrane
16. Sclera
17. Suprachoroid layer (lamina fusca)with chromatophores
18. Vascular layer of the choroid
19. Choriocapillary layer

31. THE ROD CELLS AND THE CONE CELLS
Photo pigment : Visual purple or rhodopsin
Each retina has about 120 million rods
Sensitive to light and the receptors used when low levels of light

32. The Cone cells : Photo pigment : iodopsin
Each retina has about 6 million cones
Sensitive only to light of a higher intensity
Maximum sensitive is in the red, green or blue of the visible spectrum

33. Narrow collar
Outer limiting membrane (Composed of terminal bars and filaments of mueller cells)
Mueller cell cytoplasm
Discs
Outer segments
Cilium
Inner segments
Nuclei
Synapses
Processes of bipolar cells

34. The light and the nervous impulses travel in the retina
Diagram showing the arrangement of the three layers of neurons in the retina. Observe that the light and the nervous impulses travel in opposite directions.

35. LENS
Transparent
Biconvex, posterior surface has a greater convesity than the anterior surface
Three structural component :
Lens capsule : homogenous
Subcapsular Epithelium
Single layer of cuboidal epithelium cells
Present only on the anterior surface
Lens Fibers :
Appear as thin flattened structures
They are highly differentiated cells derived from cells of the subcapsuler epithelium

36. The lens, viewed from behind and from the side.
From section through margin of lens longitudinal sections of lens fibers and transition from epithelium to lens fibers a : Lens fibers; b: capsule; c : epithelium

37. The lens is held in place by the zonula ciliaris (Zonula of Zinn, suspensory ligament)
The Zonula on :
The lens capsule
The ciliary body
The zonula is important in process accomodation

38. Connective tissue
Lens
Anterior view of the ciliary processes showing the zonules attaching of the lens. Zonule fibers are bundles of microfilaments (oxytalan fibers) from the elastic fibers system. The zonules form column (A) on either side of the ciliary processes (B), which meet on a single site (C) as they attach to the lens.

39. THE VITREOUS BODY Transparent gell Amorphous Intercellular substance
Bounded by :
The internal limiting membrane of the retina
The lens
The posterior zonular membrane

40. A. EYELIDS Accessory structures 10. Superior tarsal muscle (of Muller)
11. Adipose tissue
12. Accessory lactrimal gland (of Krause)
13. Lymphatic tissue
14. Epithelium of palpebral conjuctiva
15. Tarsal glands (Meibomian glands)
16. Tarsus
17. Palpebral conjuctiva
18. Duct of tarsal gland (Meibomian gland)
19. Ciliary muscle (of Riolan)
20. Hair follicles of eyelashes
1. Hair follicles
2. Sweat glands
3. Epidermis and dermis
4. Rudimentary hari follicle
5. Palpebral part of orbicularis oculi muscle
6. Connective tissue
7. Arteriole
8. Ciliary glands : large sweat glands (of Moll)
9. Sebaceous glands (of Zeiss)

41. B. Lacrimal Apparatus Consists of : The lacrimal gland Canaliculi
Lacrimal sac
Nasolacrimal duct

42. The Lacrimal Gland : Tear secreting gland
Located in the anterior superior temporal portion of the orbit
Consist of several separate glandular lobes
Tubulo alveolar
Serous type
Myoepithelial cells surround the secretory portions

43. LACRIMAL GLAND 6. Venule 1. Glandular alveoli 7. Interlobular duct
2. Intralobular ducts
3. Myoepithelial cell (basal or basket cell)
4. Interlobular connective tissue
5. Outpocketing of glandular cells
6. Venule
7. Interlobular duct
8. Glandular alveoli
9. Interalveolar connective tissue
10. Arteries
11. Interlobular duct

44. DRAINAGE OF TEARS Lacrimal Gland
Cornea, Bulbar and palpebral conjunctiva
Lacrimal Puncta
Lacrimal Canaliculi
Lacrimal Sac
Nasolacrimal Duct
Inferior meatus of nasal cavity

45. THE LACRIMAL DRAINAGE SYSTEM