By. Chittranjan kumar Enternship

Definition :- It is the procedure performed to determine the intraocular pressure (IOP)

Def. of Glaucoma It is the characteristic and progressive condition of the eye which is raised the intraocular pressure occurs progressively damage the optic nerve fibers due to gradually loss of vision.

Direct Indirect

Manometer

DIGITAL INDETATION(Schiotz)

APPLANATION

(Goldman)

NCT

Types of Tonometer

Perkin’s

DirectTonometery

Procedure:- -Cannula inserted into the the

Eye -Then connected to a tube of

calibrated in cm of water or mercury(mmhg)

Disadvantage :- -Not clinical method - Needs Anaesthesia

Manometry

Indirect Tonometery

Principle:-

-Based on Palpation By the Examiner

Procedure:- -Pt looks Down -Index finger of both hand used one

finger push eye ball above tarsal plate that time other finger palpation the process.

Digital Tonometry

Advantage :- -Easiest -No equipment -No anaesthesia -No staining Disadvantage:- -Reading not proper -Only depend on examiner -Miner IOP can’t judged

properly

Indentation tonometer (Schiotz)Principle:- - Amount of the indentation depends upon IOP

-The higher IOP the lesser

Indentation -The lesser theIOP the deeper the indentation

-Less reading on scale ---- High IOP

-Scale reading have to be converted to IOP by the help of chart (Friedenwald conversion table)

HENCE

Plunger of tonometer Indenting the cornea

Base plate of tonometer resting on cornea

Fig.1 In this cornea is indented

PART OF SCHIOTZ TONOMETER

scale

Needle

Weight 5.5g plunger

Holder

Foot plate

lever

Additional weights 7.5,10,15g

Pseudocornea

Process :- -Patient in supine position - 4%lignocaine/proparacaine -looking up at a fixation targetAdvantage:- - Fast - Very good to camp screening

- Portable - Cheep - Easy to cleaning &

maintenance - No required Slit lamp /

electricity

Disadvantage :- - Reading effect by corneo scleral rigidity

- Can not be done in injury cases/early post-op

Cleaning& Mantanance:- - Cleaning after the removed from

barrel with

> Alcohal > Methylated spirt

Calibration:- This instrument should be calibrated before each use by placing on pseudo cornea and be sure checking scale reading is zero.

Applanation tonometer Principle:- -Applanation tonometer based on IMBERT FICK LAW

- Biprism tip flattens - A Biprism convert applantion area into half alignment of 2 half give the correct IOP reading

- Applanates a small area of cornea central 3.06mm.

F- ForceA- Flattening of the areaP- Pressure in side the Eye

IMBERT FICK LAW

Parts of Applanation tonometer

Biprism (measuring prism)Feeder arm

Housing

Adjusting knob

Connects to the slit lamp

Control weight insert

Equipment:- -Housing control the prism

movement-Neck-Biprism plastic Biprism with

a mirror to slit corneal applantion image to 2 halves

Process:--slit lamp-4% xylocaine -Dark room- Flurosceine stain of tear

film-Cobalt blue light -Biprism applanation cornea

with knobs reading at (1)-Reading read on knobs

scale multiplied by 10 ====IOP

Advantage:–

- Most accurate . -No indentation so not

much force applied on cornea. -Does not effect by

cornea scleral rigidity . -Reading directly read

from knob . -Can be done on post op case /injury cases .

Disadvantage :-

-Need slit lamp -Dark room .

- Need staining cobalt light

Calibration:-◦ Appl, tonometer is calibrated with calibration bar.

◦ It should be done once in a weekly or monthly depend upon uses.

NON CONTACT TONOMETER

Principle :-

A puff of air creates a constant force that momentarily flattens the cornea and internal reference point to the movement of flattening is measured and converted into IOP .Directly reading on display.

Fig:- NCT

Process:-

ADVANTAGE ;- -Quick . -No anesthetic required

. -May be delegated . -Nothing contact to the

Eye .

DISADVANTAGE :- -Expensive . -Difficult on to obtain reading

on scarred cornea , soft Eye -Not partable ..

Perkins TonometerIt uses the same biprism as the Goldmann

applanator.

The light source is powered by battery.

The readings are consistent and compare quite well with the Goldmann applanator.