IOP | Tonometry | NCT | Goldmann's Tonometer

2. Lovepreet Singh (43/2017)
Madhav Mehta (44/2017)
Madhav Singla (45/2017)
Mahakdeep Kohli (46/2017)

3. What is Tonometry

4. Measurement of the
Intra-Ocular Pressure
• Normal IOP: 12-22 mmHg
• Raised IOP can lead to damage of
OPTIC NERVE leading to loss of vision (GLAUCOMA)

6. NEEDLE
HANDLE
FOOT PLATE

7. • Sterilize
• Anaesthetise
• Record
Start with 5.5 gm Weight but if the
reading is <3, add weight to make it
7.5gm/10gm
Because with Schiotz tonom. the
Greatest accuracy is attained if the
deflection is b/w 3-4.

8. v
Cheap, Handy, Easy
False reading

9. Introduced by Goldman in 1954

10. Applanation Tonometer
Based on Limbert-Fick Law
P=F/AP = pressure inside a sphere
F = force required to flatten its surface
A = area of flattening

11. Commonly used
are
1. Goldmann tonometer
2. Perkin’s applanation tonometer
3. Pneumatic tonometer
4. Pulse air tonometer
5. Tono-Pen

12. Goldmann tonometer
Most popular & accurate
Double prism mounted on a standard slit-lamp

13. Goldmann tonometer
Most popular & accurate
Double prism mounted on a standard slit-lamp
Double prisms
• Applanates the cornea with a diameter of 3.06 mm

14. Perkin’s tonometer
Same principle as of Goldmann
Easy to carry, Handheld, Convenient

15. Forehead Rest
Double Prism
Scale
Eye piece
Perkin’s tonometer

16. Sterilize
Anaesthetise
Stain with Dye
Observe under BLUE light & Applanate
Adjust till Inner margins of the
Semicircles (Mires) just touch.
Fluorescent

17. MIRE 01
MIRE 02
Inner margins of
The MIRES just
touching each other.

18. Pulse Air tonometer
Quick, prevents communicable eye infections
Non-Contact Tonometry

19. • The Pulse Air Tonometer releases air over a range of pressures at your eye. At
the same time, an infrared beam of light is shone off your cornea.
• When the cornea flattens out under the pressure of the air, the beam of light
reflects at a different angle.
• When this occurs, the device records the pressure of the air that was required,
measured in millimetres (mm) of mercury (Hg)

21. Tonopen
Handheld
Works on the same principle
as of Mackay-Marg tonometer

23. GONIOSCOPY
● Technique of biomicroscopic examination of angle of
anterior chamber is known as Gonioscopy.
● Device used is Goniolens.
Indirect Direct
provides mirror image provides direct view of of angle.
Angle.
e.g. Goldmann goniolens. e.g. Koeppe goniolens

24. ANGLE STRUCTURES
• As seen behind forward are:
1) Root of iris
2) Ciliary band
3)Scleral spur
4)Trabecular meshwork and Schlemm's canal.
5) Schwalbe's line.

25. Schwalbe’s line

27. PRINCIPLE
It is impossible to visualize angle of anterior chamber by direct examination
due to two reasons i.e. opacity of corneoscleral junction and total internal
reflection of light emitted from angle structures through anterior surface of
cornea.
Hence goniolens is used to divert beam of light to make examination of
angle possible.
Procedure
Patient is seated upright on slit lamp.
A drop of methylcellulose is placed in concavity of goniolens.
With patient looking up one edge of lens is positioned on lower fornix.
Upper eyelid is lifted elevated and patient is instructed to look straight
ahead.
The lens is rotated into position against eye.

30. Applications of Gonioscopy
1) Classification of Glaucoma.
2) Localization of foreign bodies, abnormal blood vessels or tumours in angle.
3) Demonstration of peripheral anterior synechiae(PAS) extent and hence planning of glaucoma
surgery.
4) Surgical aid direct goniolens is used during goniotomy.