Human Eye Prepared By RASHIDUL HASAN ROBEL B. PHARM (RU), M. PHARM (RU) REG. NO. A4968 PGD-HRM (BIM) EMBA (ULAB)

1. HUMAN
EYE
PREPARED BY
RASHIDUL HASAN ROBEL
B. PHARM (RU), M. PHARM (RU)
REG. NO. A4968
PGD-HRM (BIM)
EMBA (ULAB)

2. HUMAN EYE
Human eye is an organ that reacts with light and allows
light perception, color vision and depth perception.
• Shape: Spherical (slightly elongated)
• Size: 2.3cm-2.4cm in diameter
Horizontal = 24.2 mm
Vertical = 23.7 mm
Axial = 22.0-24.8 mm
• Can see about 10 million different colors!

3. EYE PARTS

4. EYELIDS
• Folds of skin that cover & protect the eye
• Contain ‘eyelashes’ that protect the eye from dust
• Contain ‘meibomian glands’ that secrets oil which lubricates the eye surface
• Help in tear drainage
• Control light entering the eye
• Maintain normal eye blinking 10-15/min
• Blepharitis: chronic inflammation of eyelids

5. MEIBOMIAN GLAND
• Location: borderline of eyelids
• Also called oil producing gland
• 50 glands on upper eyelid & 25 glands on lower eyelid
• Secrets oil that comprises oil layer of tear film
• Secrets oil that lubricates the eye surface & prevents evaporation of tear
• Meibomitis: inflammation of meibomian gland

6. ZEIS GLAND
• Location: root of eyelash
• Secrets oil
• Stye: inflammation of zeis gland

7. LACRIMAL GLAND
• Location: upper lateral region of each orbit & behind upper eyelid
• Secrets tear 90% that comprises aqueous layer of tear film
• Also called tear producing gland
• Dacryoadenitis: inflammation of lacrimal gland
Tear Drainage Pathway
Lacrimal Gland
Eye Surface
Punctum
Superior & Inferior Canaliculi
Naso-Lacrimal Sac
Naso-Lacrimal Duct

8. TEAR
• Salty fluid mostly produced from lacrimal gland
• Moistens the eye surface & washout debris
• Contains mostly water & electrolyte that maintains isotonicity
• Contains antibodies & lysozyme that kill germ

9. TEAR FILM
• Location: just above cornea
• 3 layers of tear film
Outer layer : Lipid layer that lubricates the eye & prevents evaporation
Middle layer : Aqueous layer that moistens the eye surface & kills pathogen
Inner layer : Mucous layer that covers the cornea & adheres tears to the eye

10. GLYCOCALYX
• Location: between tear film & cornea
• Glycocalyx is produced by corneal epithelial cell
• Glycocalyx helps to bind mucins onto the corneal surface

11. CORNEA
• Location: below the tear film & attached to sclera
• Has 5 different layers (bowman’s layer, epithelium, stroma, descemet's membrane
& endothelium).
• Bends incoming light as it enters the eye
• Human cornea absorbs light below 295 nm shorter wavelength.
• Keratitis: inflammation of cornea

12. CONJUNCTIVA
• Location: it lines the inside of eyelids & covers the sclera
• Contains ‘goblet cell’ that secrets mucin which forms mucous layer of tear film
• Conjunctivitis: inflammation of conjunctiva
• Kerato-conjunctivitis: inflammation of both cornea & conjunctiva
• Blepharo-conjunctivitis: inflammation of both eyelids & conjunctiva

13. SCLERA
• Location: above the choroid & attached to cornea
• White part of the eye.
• Tough outer layer of the eye that covers & protects the eyeball.
• Eye muscles are attached to sclera that moves the eye.
• Scleritis: inflammation of sclera

14. IRIS
• Location: attached with ciliary body & choroid and
below cornea & above lens
• Pigments (melanin & lipochrome) present in iris that provides eye color
• Controls how much light enters the eye by changing the size of pupil
• Iritis: inflammation of iris

15. PUPIL
• A hole like structure of iris that allows the light to enter into eye
• It leads the light to the lens

16. Bright Light
Iris circular muscles
constrict & radial
muscles relax
Pupil constricts
Dim Light
Iris circular muscles
relax & radial muscles
constrict
Pupil dilates
Circular muscles constrict
Radial muscles relax
Parasympathetic
(acetylcholine)
Circular muscles relax
Radial muscles constrict
Sympathetic action
(noradrenaline)

17. CILIARY BODY
• Location: it is attached to choroid, iris & suspensory ligaments.
• Produce & release aqueous humor
• It attaches suspensory ligaments that holds the lens
• Contains ciliary muscles
• Cyclitis: inflammation of ciliary body

18. LENS
• Transparent lens attached to suspensory ligament
• Encapsulated biconcave lens change its shape due to presence of collagen fiber
• Focusing the light onto retina
• Matured lens is crystalline due to presence of crystallin proteins & absence of
nucleus, mitochondria etc.
• UV light does not harm retina. Because human lens absorbs most UV light 300-
400 nm wavelength.
Accommodation
Ability of the eye to
change its focus
from distant to
near objects. This
process is done by
the lens changing
its shape.

19. Short focal distance
Ciliary muscle contracts &
suspensory ligaments loosen
Lens become thicker &
rounder
Long focal distance
Ciliary muscle relaxes &
suspensory ligaments tighten
Lens become thinner &
flatter

20. SUSPENSORY LIGAMENTS
• Location: between ciliary body & lens
• Changes the shape of lens

21. CHOROID
• Location: above retina & below sclera
• In front of the eye, choroid attaches to ciliary body & iris
• Contains blood vessels
• Nourishes the retina
• Provides blood supply to ciliary body & iris
• Absorbs excess light & prevents internal light refection
• Regulates retinal heat
• Assists in IOP
• Choroiditis: inflammation of choroid

22. UVEA
• Uvea or uveal tract consists of iris, ciliary body & choroid
• In front of the eye, choroid attaches to ciliary body & iris
• Uveitis: inflammation of uvea

23. RETINA
• Location: below the choroid
• Contains photoreceptors; both rods & cones
• Receives light & converts it into electric signals
• Retinitis: inflammation of retina
• Retinopathy: damage of retina

24. RODS
• Photosensitive cell present in retina
• Receives black & white light & converts the light into electric signal
• It works in dim light or night time
• 120 million rods are found in retina
CONES
• Photosensitive cell present in retina
• Receives colored light & converts the light into electric signal
• It works in bright light or day time
• 6 million cones are found in retina

25. MACULA
• Location: on retina
• Contains fovea
FOVEA
• Location: in macula
• Contains photoreceptor ‘cones’

26. OPTIC NERVE
• Location: back portion of eyeball
• Transfer visual electric impulse from retina to brain (visual cortex)
• Optic neuritis: inflammation of optic nerve
Optic Nerve

27. BLIND SPOT
• Location: retina
• Blind spot has no photoreceptors

28. AQUEOUS HUMOR
• Location: transparent & colorless liquid between cornea & lens
• Produced & released from ciliary body
• Maintains IOP & inflates the front globe of eye
• Contains vit-C or ascorbic acid that provides anti-oxidant property
• Contains antibody that kills pathogen
Composition of Aq. Humor
• water - 98.69%
• glucose
• vit-C or ascorbic acid
• proteins
• amino acid
• gases O2 & CO2
• antibody, lysozyme etc.
• electrolytes
Na+, K+, HCO3-, Cl-

29. AQUEOUS HUMOR
Production site : Ciliary body
Production rate : 2.0–3.0 µL/min
Total volume : 310 µL
Turnover: 1.5 – 2 hours
Drainage way : Trabecular meshwork - 80%
Uveoscleral outflow - 20%
Location : between lens & cornea
Color : Transparent/colorless fluid
pH : 7.2 – 7.4 (mild alkaline)
Osmolarity : 304 mOsm/L

30. Intra-Ocular Pressure/Eye Pressure
Intra Ocular Pressure (IOP) means aqueous humor fluid pressure inside the
eye. Normal IOP is 10-21 mm Hg.
IOP may increase due to
 Excessive aqueous humor production,
 Inadequate aqueous humor drainage through trabecular meshwork &
 Aqueous humor drainage through uveo-scleral outflow.

31. VITREOUS HUMOR
• Location: colorless jelly like substance between lens & retina
• Acts as refractive medium
• Maintains shape & pressure of the eyeball
Composition of Vit. Humor
• water - 99%
• collagen fibrils
• hyaluronic acid
• vit-C or ascorbic acid
• glucose
• electrolytes
Na+, K+, HCO3-, Cl-

32. EYE MUSCLE
06 eye muscles