The document discusses the fluid system of the eye. It describes that the vitreous humor is a gel-like fluid located behind the lens and in front of the retina that helps maintain the shape of the eye. The vitreous humor is transparent and avascular. The document also discusses the aqueous humor, which is secreted by the ciliary processes and flows through the anterior chamber, maintaining intraocular pressure and supplying nutrition to the eye. Measurement of intraocular pressure is important, as pressure increases can lead to glaucoma and vision loss.

2. The fluid system of the eye
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

3. • Located behind the lens & in
front of the retina
• Filled with a gel-like fluid
called the vitreous humor
• The vitreous humor is
transparent, avascular& help
maintain the shape of the eye
Vitreous Chamber

4. 4
Aqueous Humor
Sclera
Iris
Lens
Aqueous humor
Cornea
Vitreous humor
Ciliary process
Ciliary muscles
Posterior
chamber
Ciliary
body
Scleral venous sinus
(canal of Schlemm)
Anterior
chamber

5. Aqueous humor circulation
• Ciliary processes in posterior chamber secrete aqueous fluid. It flows between
the ligament of the lens and then through the pupil into the anterior chamber of
the eye. Then fluid passes into the angle between the cornea and the iris.
Through the meshwork of trabeculli aqueous humor enters the channel of
Slemm, which empties into extraoccular veins.
• Functions of aqueous humor: 1) maintains intraoccular pressure; 2) maintains
shape of eyeball; 3) acts as refractory medium; 4) supplies nutrition; 5) drains
metabolic end products.

6. Mechanism of formation of aqueous humor:
Active Na transport by Na
/K pump.
Passive Cl & HCO3
Passive H2o

7. • Located where the cornea
meets the iris
• Trabecular Meshwork
• Site where aqueous humor
drains out of eye
• If AH cannot properly drain out
• Pressure build up inside eye
• Causes optic nerve damage &
evetually vision loss =
glaucoma
http://seniorhealth.about.com/library/conditions/blglaucoma2.htm
Anterior Chamber Angle

9. INTRAOCULAR PRESSURE

10. • the tissue pressure of the ocular contents
• about 15 mm Hg but diurenally fluctuate (15.5 +/- 2.57)
• normal range of pressures: 12 – 20
DEFINITION

11. regulation

13. General factors that affect
measured IOP
General
Diurnal variation — IOP generally higher in the morning vs
afternoon; normal fluctuation 2–5 mm Hg
Posture — higher in supine vs sitting position. Highest in
head down position
Exercise — aerobic exercise generally lowers IOP, while
isometric exercise can increase IOP
Canadian Ophthalmological Society evidence-based clinical
practice guidelines for the management of glaucoma in the adult
eye. Can J Ophthalmol 2009;44(Suppl 1):S1S93.

14. III. FACTORS THAT INFLUENCE IOP
• 2. Sitting - going from a sitting
to a lying position results in an
increase in IOP which is even
greater in glaucoma patients
• 3. Total Body Inversion -
causes an increase in IOP by
as much as 15 mm Hg

15. 1. Indentation tonometry
• the older of the 2 methods to measure IOP in humans
• involves measuring the indentation of the cornea resulting from a given weight
• the Schiotz tonometer is an indentation tonometer
• the weight of the tonometer displaces fluid in the eye and thus affects the IOP
measurement
IV. MEASUREMENT OF IOP
Tonometry

17. Indentation tonometer

19. 2- Applanation tonometers
• Applanation tonometers measure the force needed to
flatten or applanate a small area of the centeral
cornea. The greater the force needed to flatten a
known area of the cornea, the higher IOP.

21. Tonometry mires
Figure 1—Excess corneal applanation
(IOP lower than tonometer reading)

22. Tonometry mires
Figures 2 and 3—Insufficient corneal applanation
(IOP higher than tonometer reading)

23. Glaucoma

24. Definition
Causes
Effects:
• Blindness
• Mydriasis
• Sever eye pain
Glaucoma

25. Figure 9-12(b)

27. • Decrease formation : diamox
• Increase drainage
• Medical :pilocarpine surgical
Treatment