for ophthalmc assistant

1. WINTERTemplateIntraocular pressure
and tonometry
01

2. Intraocular pressure
• What is intraocular pressure?
• What unit?
• Normal range
• Causes of abnormal
measurement

3. Anatomy and physiology

4. Diurnal variation

5. Factors that may increase IOP

6. Factors that may decrease IOP

7. Tonometry
• Definition
Tonometry is the measurement of
intraocular pressure by a tonometer

8. Types of tonometer
Applanation tonometer Indentation tonometer
• Goldmann applanation tonometer
• Perkins tonometer
• Pneumatic tonometer
• Tonopen
• Noncontact(air-puff) tonometer
• Schiotz tonometer

9. Goldmann applanation tonometer
• ‘GOLD STANDARD’
• Based on Imbert-Fick principle
 Pressure=force/area of flattening
• Mounted on a slit-lamp biomicroscope

11. Parts of the instrument
1.Tonometer tip
2. Metal rod
3. Housing
4.Force adjustment
knob

12. Performing goldmann applanation
tonometry

13. Disinfecting the applanating tip
• Remove the tonometer tip from the biprism
after each use
• Disinfect by swabbing the tip with a cotton-
tipped applicator that has been soaked in
isopropyl alcohol
• Rinse the tip with water and dry with
gauze.

14. Contraindications
• Active infections
• Recurrent corneal erosions
• Corneal abrasions that are not healed

15. Schiotz indentation tonometry
• Inexpensive, portable, easy to
use instrument
Advantages Disadvantages
• Limited accuracy in conditions like high myopia,
following surgery and corneal oedema
• Uses the fact that a plunger will indent a soft
eyeball more than a hard one

16. Parts of instrument
Curved metal foot plate
Metal plunger
Frame with handles
Variety of weights
Numbered scale
Indicator needle
Hammer

17. Performing schiotz tonometry

18. Disinfecting schiotz tonometer
• Remove the plunger from the cylinder
• Wipe the footplate and the plunger with
the alcohol
• Rinse the footplate and plunger with water
and wipe it with gauze

19. Contraindications

20. Rebound tonometry
• bounce a magnetized probe off the cornea
and detect the deceleration of the probe
caused by the eye.
• The deceleration is more rapid if the IOP is
high and slower if the IOP is low.
• The probes are disposable between patients,
so, disinfection is not necessary
Disadvantage of this tonometer is that it can
only be used in an upright patient (the probe
falls out if the instrument is facing downward)

21. Parts of rebound tonometer
Display
Selector button
Measurement button
Grip
Forehead support
Forehead supporting adjusting
wheel
probe

22. Performing rebound tonometry

23. Digital tonometry
• Rough estimation of intraocular pressure
by finger tips especially in uncooperative
patients or in absence of instruments.

25. Recap
• Name one cause of ocular hypotony
• IOP is highest in the morning. T/F
• Name one drug which can cause increased
IOP
• What is the gold standard instrument to
measure IOP?
• Name one contraindication for schiotz
tonometer.

26. Thank you