The document discusses tonometry, a procedure for measuring intraocular pressure (IOP), detailing various types including direct and indirect methods such as applanation, indentation, and non-contact tonometers. Key instruments like the Goldman tonometer, Perkins tonometer, and pneumatic tonometer are described, along with their advantages, disadvantages, and procedures involved. The document emphasizes the importance of accurate measurement, potential errors, and the overall significance of tonometry in ophthalmic practice.

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