TONOMETRY • Tonometry is the procedure performed to determine the intraocular pressure (IOP). 3.  CLASSIFICATION TONOMETRY DIRECT INDIRECT Indentation Applanation Manometer 4. APPLANATION Contact Non-contact Goldmann Perkins Air-puff Pulse air 5. INDENTATION TONOMETER • It is based on fundamental fact that plunger will indent a soft eye more than hard eye. • The indentation tonometer in current use is that of Schiotz . • It was devised in 1905 and continued to refine it through 1927. 6. PROCEDURE • Patient should be anaesthetising with 4% lignocaine or 0.5% proparacaine. • with the patient in supine position, looking up at a fixation target while examiners separates the lids and lower the tonometer plate to rest on the cornea so that plunger is free to move. •

1. TOPIC:TONOMETRY
MODERATOR: MS HUMA NAAZ
PRESENTER : DUSHYANT SINGH

2. TONOMETRY
• Tonometry is the procedure performed to
determine the intraocular pressure (IOP).

3.  CLASSIFICATION
TONOMETRY
DIRECT INDIRECT
Indentation Applanation Manometer

4. APPLANATION
Contact Non-contact
Goldmann Perkins Air-puff Pulse air

5. INDENTATION TONOMETER
• It is based on fundamental fact that
plunger will indent a soft eye more than
hard eye.
• The indentation tonometer in current
use is that of Schiotz .
• It was devised in 1905 and continued
to refine it through 1927.

6. PROCEDURE
• Patient should be anaesthetising with 4%
lignocaine or 0.5% proparacaine.
• with the patient in supine position, looking up
at a fixation target while examiners separates
the lids and lower the tonometer plate to rest
on the cornea so that plunger is free to move.
• The 5.5gm weight is initially used.
• If the scale reading is 4 or less , additional
weight is added.

8. ADVANTAGES
•Simple Technique
•Elegant design
•Portable
•No need for slit lamp or power supply
•Reasonably priced
•Widely used tonometer

9. Applanation tonometers
• Goldman tonometer
• Perkins applanation tonometer
• Pneumatic tonometer
• Tono pen

10. Goldmann tonometry
• The concept was introduced by goldmann in
1954
• It is based on IMBERT FICK LAW
• It states that the pressure inside an ideal
sphere (P) is equal to force (F) required to
flatten(A)
• P=F/A

11. Cont…
• Most popular and accurate tonometer.
• It consists of double prism mounted on slit
lamp.
• The prism applanates the cornea in an area of
3.06 mm diameter.

12. Technique
• Topical anesthesia
• Staining tear film with fluorescein.
• The cornea and biprisms are illuminated with
cobalt blue light.
• Biprism just touches the apex of cornea.
• At this point two fluorescent semicircles are
viewed through prism.

13. • Applanation force against cornea is adjusted
until inner edges of two semicircles just
touches.

14. Potential errors
• Patient related
• Thin cornea
• Thick cornea
• Astigmatism
• Irregular cornea

15. • Technical
• Tonometer out of calibration
• Repeated tonometry
• Pressing on the eyelids or globe
• Squeezing of the eyelids

16. Advantages
• Highly accurate
• Do not requires supine position
• portable
Disadvantages
• Not portable
• costly
• reading error if scares on cornea

17. Perkins Tonometer
• It uses the same biprism as the Goldmann
applanation.
• The light source is powered by battery.
• The readings are consistent and compared
quite well with the Goldmann applanation.

18. Perkins Tonometer
• Perkins –
• Handheld
• Horizontal as well as vertical
• Infants, children, recumbent patients

19. Advantages
• Portable
• Does not requires electricity
Disadvantage
• It requires supine position
• Costly

20. Pneumatic tonometer
• Cornea is applanated by touching apex by
silastic diaphragm covering sensing nozzle.
• It is connected to central chamber containing
pressurized air.
• There is pneumatic to electronic transducer.
• It converts the air pressure to recording on
paper strip and IOP is red.

21. Pneumatic tonometer

22. Tono pen
This is handheld Mackay Marg type tonometer
It is a computerised pocket tonometer
It converts IOP into electric waves

23. Cont…
• The wave form is internally analyzed by a
microprocessor.
• Three to six estimations of the pressure are
then averaged.
• The instrument is 18 cm in length and weighs
60 g.

24. NON-CONTACT TYPE
• Air puff tonometer :- In this central part of
cornea is flattened by a jet of air . This
tonometer is very good for mass screening as
there is no danger of cross infection and local
anaesthetic is not required.
• Pulse air tonometer :- It is a non-contact
tonometer that can be used with the patient
in any position.

25. THANK YOU