Keeler KAT User manual

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Instructions for use
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Keeler Applanation Tonometer (KAT)

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Contents
1. Introduction
1.1 Brief description of the instrument
1.2 Intended use / purpose of instrument
1.3 How the intraocular pressure is measured
1.4 Advantages of using a Goldmann Tonometer
2. Symbols used
3. Safety
3.1 Standards applied
3.2 Warnings and Cautions
4. Cleaning and disinfection instruction
4.1 Cleaning Tonometer body
4.2 Disinfecting the Tonometer prisms
5. Tonometer Prism field check
6. Name of components of R type and T type KAT
7. Measurement procedure
7.1 Installation on to the Slit Lamp
7.1.1 Keeler Applanation Tonometer (T type)
7.1.2 Applanation Tonometer ‘Keeler Fixed’ (R type)
7.2 Preparing the patient
7.3 Preparing the Slit Lamp instrument for examinations
at 10 x magnification
7.4 Using the instrument/ taking a measurement
7.4.1 Instructions to the patient
7.4.2 Taking the measurement
8. Problem solving
9. General information and suggestions concerning measurement
10. Astigmatism
11. Routine instrument maintenance
11.1 Check procedure with the measurement drum set to 0
11.2 Check procedure with measurement drum set to 2
11.3 Check procedure with the calibration arm set to 6
12. Servicing and calibration
13. Specifications
13.1 Transport, storage and working conditions
13.2 Technical specifications
14. Accessories and warranty
15. Contact information
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As part of our policy for continued product development we reserve the right to amend specifications at any time without prior notice.

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1. Introduction
Thank you for choosing this Keeler Applanation Tonometer (KAT).
Please read this manual carefully before using your KAT.
This will ensure the safety of the patient and your confidence
in the measurements it provides. This manual should be stored
safely for future use.
1.1 Brief description of the instrument
The Keeler Applanation Tonometer operates according to the
“Goldmann method”, by measuring intraocular pressure from the
force required to flatten (applanate) a constant area (3.06mm) of
the cornea. A special disinfected (or single use) prism is mounted
on the Tonometer head and then placed against the cornea.
The examiner, using a slit lamp biomicroscope at 10x
magnification, with a blue filter views two fluorescing green
semi circles. The force applied to the Tonometer head is then
adjusted using the dial until the inner edges of these green
semi-circles meet.
Because physical contact with the cornea takes place it is
necessary to apply to the patients cornea a suitable topical
anaesthetic.
1.2 Intended use /
purpose of instrument
The Keeler Applanation Tonometer is
indicated for measuring intraocular pressure to
aid in the screening and diagnosis of glaucoma.
The Keeler Applanation Tonometer (KAT) is
an accessory item for most ‘Tower Illumination’
type of Slit Lamps and thanks to its versatility,
the KAT Tonometer can be mounted on
and used with slit lamps produced by
many manufacturers.
The KAT should be used only by trained personnel. USA Federal
law restricts this device to sale by or order of a physician.
The manufacturer declines any and all responsibility and warranty
coverage should the instrument be tampered with in any manner
or should routine maintenance be omitted or performed in
manners not in accordance with these manufacturer’s instructions.
R type (fixed) KAT on Slit Lamp

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1. Introduction
1.3 How the intraocular pressure is measured
The cornea is flattened by an acrylic measuring prism on a
ring support at the end of the Tonometer sensor arm assembly.
It is flat with smooth or rounded margins to avoid any damage
to the cornea.
The measuring prism is brought into contact with the patient’s
eye by moving the slit lamp forward. The measurement drum is
then turned to increase the pressure on the eye until a continuous,
uniform applanated surface 3.06 mm in diameter (7,354 mm² area)
is obtained. The doubling prism divides the image and presents
the two opposing semicircular halves at 3.06mm (see section 7.4.2
Measurement procedure for further details).
1.4 Advantages of using a Goldmann Type Tonometer
• Intraocular pressure can be measured during routine
examination with the Slit Lamp.
• The standard deviation among single measurements is
approximately < _ 0,5 mmHg.
• The value is expressed in mmHg and is read directly on the
instrument.
• Scleral rigidity need not be taken into consideration because
the small volume moved (0,56 mm3) increases intra-ocular
pressure by only about 2.5%.
• There are no difficulties as regard standardisation and
calibration.
Position of the
measurement drum
Force
mN
Pressure
kPa mmHg
19.81 1.33 10
2 19.62 2.66 20
3 29.43 39.9 30
4 39.24 53.2 40
5 49.05 66.5 50
6 58.86 79.8 60
7 68.67 93.1 70
8 78.48 10.64 80
Relationship between the pressure of the
measurement drum and the force and
pressure on the applanated surface.
The intra-ocular pressure, expressed in
mmHg, is calculated by multiplying the
drum measurement by ten (for conversion
from one unit to another).

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2. Symbols used
Read user instructions for Warnings, Cautions and
additional information
The CE mark on this product indicates it has been
tested to and conforms with the provisions noted
within the 93/42/EEC Medical Device Directive
Consult instructions for use
Manufacturers name and address
Keep dry
Fragile
Material suitable for recycling
0088

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3. Safety
Use this instrument only in strict accordance with the
instructions contained in this manual.
3.1 Standards applied
The Keeler Applanation Tonometer is designated as Class I
non-invasive measuring device under EC Directive 93/42/EEC for
medical equipment products.
The CE mark on this product indicates it has been tested to
and conforms to the provisions noted within the 93/42/EEC
Medical Device Directive.
It also complies with ISO 15004-1:2006 ophthalmic instruments-
Fundamental requirements and test methods and BS EN ISO
14971:2007 Medical Devices - Application of Risk Management
to Medical Devices.
Classification
CE Regulation 93/42 EEC: Class 1m (Measuring function)
FDA: Class II

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3. Safety
3.2 Warnings and Cautions
• The owner of the instrument is responsible for training
personnel in its correct use.
• Accuracy of applanation IOP measurements is known to be
affected by variations and changes in corneal rigidity due to
differences in corneal thickness, intrinsic structural factors or
corneal refractive surgery. It is recommended that these
factors are considered during IOP measurement.
• Do not use the product if visibly damaged and periodically
inspect for signs of damage or misuse.
• The contact surface of this prism should be checked before
each use for damage and discarded if damage is found.
• We recommend that the prism is not used when it becomes
more than two years of age as, after this time it is possible
that body or sterilising fluids may seep inside leading to
possible sterility and cross contamination issues.
• Only decontaminate / clean in accordance with method given
in Cleaning Section 4 of this instruction manual.
• Use only cloths dampened with water to clean the
Applanation Tonometer body. Do not use corrosive products
or alcohol.
• Keeler Applanation Tonometers should be serviced and
calibrated annually. Any servicing or repairs/modifications
should only be carried out by Keeler Ltd. or by suitably
trained and authorised distributors. The manufacturer declines
any and all responsibility for loss and/or damages resulting
from unauthorised repairs; furthermore, any such actions will
invalidate the warranty.
• Never use the instrument if the ambient temperature,
atmospheric pressure, and/or relative humidity are outside the
limits specified in this manual.
• Should the instrument suffer shocks (for example, should it
accidentally fall), follow the check procedure outlined in the
“Calibrations” section 12 ; if necessary, return the
instrument to the manufacturer for repair.
• Use only the listed accessories in conjunction with the
instrument; use said accessories only in accordance with the
procedures set forth in the instruction manuals.
• Always carefully observe the safety rules and other
precautions published herein.

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4. Cleaning and disinfection instruction
4.1 Cleaning Tonometer body
• Only manual non-immersion cleaning as described should be
used for this instrument.
• Wipe the external surface with a clean absorbent, non-shedding
cloth dampened with a water / detergent solution (2%
detergent by volume) or water / isopropyl alcohol solution (70%
IPA by volume).
• Use caution to ensure cloth is not saturated with solution.
• Surfaces must be carefully hand-dried using a clean
non-shedding cloth.
• Safely dispose of used cleaning materials.

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4. Cleaning and disinfection instruction
4.2 Disinfecting the Tonometer prisms
Always disinfect the Tonometer prisms before use. Hand hygiene
must be considered to prevent any contamination.
1Carefully remove the
Tonometer prism from
the prism holder.
2Wash the Tonometer prism
under cold running water for
approximately 1 minute, to
ensure Tonometer prism
is physically clean before
exposed to disinfection
process.
3Immerse the Tonometer prism
in the disinfectant fluid. Types
of disinfectant fluid vary.
4Rinse the disinfectant from
the prism in running water
for between 10 and 30
minutes.
5Dry the disinfected
Tonometer prism with a
clean soft cloth.
6Store the Tonometer prism in a
suitable container ready for use.
Safely dispose of the
disinfectant fluids used.
Please follow disinfectant solution guidelines for instructions, concentration and
time of immersion. (For example: Pantasept - 3% aqueous solution for 10 minutes,
Hydrogen Peroxide 3% aqueous solution for 10 minutes, Sodium Hypochlorite,
10% aqueous solution for 10 minutes etc.).
Do not disinfect using
the following:
Alcohol, Acetone, UV radiation,
Sterilisation, Immersion in fluid for
more than one hour,
Temperatures greater than 60°C
1 min
10 mins
10-30
mins

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5. Tonometer Prism field check
Check Tonometer prism under Slit lamp and ensure there is no
cracks/chips. Chemical used in diagnosis process (for example:
Fluorescein) will get into the cracks and will show up if observed
under slit lamp. Do not use it if there is any sign of crack or chip.

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R type KAT (fixed)
Part number: 2414-P-2040
3
1
7
4
5
2
6. Name of components of R type and T type KAT
1. Control weight housing
2. Rotating measurement knob
3. Doubling prism
4. Measurement arm
5. Manufacturers data
6. T type mounting assembly
7. R type mounting assembly
8. Calibration arm assembly
T type KAT (take-away)
Part number: 2414-P-2030
3
8
4
5
6
2
1

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7. Measurement procedure
7.1 Installation on to the Slit Lamp
Before installing the Tonometer on a Slit Lamp ensure that they
are mutually suitable.
7.1.1 Keeler Applanation Tonometer (T type)
• Position the guide plate in the Tonometer/test bar support hole
on the slit lamp.
• Lift Tonometer out of the packaging and assemble it by
inserting the pin on its base into one of the two possible
openings (for right or left eye) on the horizontal guide plate
above the slit lamp axis. These positions are related to the
microscope optics and observation can be made either through
the right or the left eye-piece.
• The Tonometer will slip easily onto the support plate; stability is
assured by the locking pins.
• To obtain an image as clear and as free of reflexes as possible,
the angle between the illumination and the microscope should
be about 60° and the slit diaphragm should be fully opened.
• When not in use the Tonometer should be removed from the
Slit Lamp and placed securely back in the packaging or a
suitable location.
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Guide Plate

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7. Measurement procedure
7.1.2 Applanation Tonometer ‘Keeler Fixed’ (R type)
This instrument is for those who wish the Tonometer to remain
permanently on the slit lamp.
• Mount the plate for the Tonometer onto the microscope body
using the securing screw.
• Then mount the Tonometer mount onto the mounting post.
• Swing the Tonometer forward in front of the microscope for
examination. A notch position ensures exact centring of the
prism with the left objective.
• To obtain an image as clear and as free of reflexes as possible,
the angle between the illumination and the microscope should
be about 60° and the slit diaphragm should be fully opened.
• When not in use the instrument is swung around and secured in
a notch position to the right of the microscope.
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Mounting
plate

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7. Measurement procedure
7.2 Preparing the patient
• Use an appropriate topical anaesthetic to numb the cornea.
• Place a strip of fluorescein-soaked paper near the outer
canthus in the lower conjunctival sac. After a few seconds the
lacrimal fluid will be colored and the paper may be removed.
When using drops, we recommend a 0.5% solution of
fluorescein sodium. If using a 1% or 2% solution, use a glass
rod to introduce a small quantity of liquid into the
conjunctival sac.
• Seat the patient at the Slit Lamp and place his chin on the
chinrest and ensure the forehead touches the forehead rest.
• Adjust the chinrest height so that the patients eye is at the
correct height (most Slit lamps have a marker on the chinrest
pole for correct height adjustment).
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7. Measurement procedure
7.3 Preparing the Slit Lamp instrument for
examinations at 10 x magnification
• Before beginning measurement, check that the eyepieces of
Slit Lamp are correctly focused.
• Set the brightness control of the instrument to position a low
intensity.
• Set the illumination angle of the Slit Lamp to be
approximately 60° to minimise unwanted reflections.
• Insert the blue filter on the slit lamp beam path and fully
open the slit diaphragm.
• Clean the doubling prism with Pantasept fluid at between
0.5% and 3.0% concentration or with a similar disinfectant
solution that is innocuous to organic glass (“plexiglass”).
After cleaning, rinse the doubling prisms in distilled
water and allow to dry. Full instructions on cleaning the prism
is covered earlier in this manual.
• Place the doubling prism on into the holder and align the
‘zero mark’ with the white alignment line on the prism
holder, this ensures the mires have a horizontal split.
• Insert the measurement arm so that the measurement head
and microscope optics axes are convergent.
• Rotate the measurement drum to position 1.
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7. Measurement procedure
7.4 Using the instrument/ taking a measurement
7.4.1 Instructions to the patient
• The patient’s head must be firmly positioned on the chin rest
and the forehead rest. If necessary, a band may be used to
hold the head still.
• Ask the patient to look straight ahead. If necessary, use a
fixation target to keep the eyes still.
• We recommend occasionally reminding the patient during the
examination, to keep his/her eyes wide open. If necessary, the
examiner may use the tips of his fingers to hold the lids open,
taking care not to exert pressure on the eye.
• When elevating the lids, the angle between the microscope
and the lighting unit must be reduced to about 10°, so
that the light beam passes through the body of the prism. In
this position it should be possible to obtain an image with no
reflections.
• Immediately before measurement, ask the patient to close
his/her eyes for a few seconds, in order to ensure that the
cornea be sufficiently wetted by the lacrimal fluid containing
the fluorescein solution.
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7. Measurement procedure
7.4.2 Taking the measurement
• Move the slit lamp forward to bring the measuring
prism into contact with the centre of the cornea in the area
above the pupil. The limbus will be illuminated with a bluish
light. The examiner will be able to better directly observe this
phenomenon from the opposite side.
• As soon as the corneal limbus is correctly illuminated,
immediately stop all forward movement of the slit lamp.
• After contact is established, observe the cornea through
the microscope. With the measurement drum set to position
1, the two semicircular fluorescein rings (which will vary in
size according to ocular pressure) will pulse rhythmically
when the Tonometer is in the correct position for
measurement.
• Use the Slit Lamp joystick control to make any corrections
needed until the applanated surface is observed as two
semicircular surfaces of equal area at the Centre of the field
of vision. (Figure 1). Small adjustments downward made with
the joystick will have no effect on the sizes of the semicircular
images.
• Increase applanation pressure by rotating the Tonometer
measurement drum until the margins of the fluorescein rings
touch and the cross as the eye pulses (Figure 2). The width of
the fluorescein rings around the contact position of the
measuring prism should be equal to about 1/10 of the
diameter of the applanation surface (0,3 mm).
• To read the scale, multiply the readings by a factor of ten
(10). The result is the ocular pressure expressed in mmHg.
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Figure 1: Semicircular images at the
Centre of the field of vision.
Figure 2: Correct Final Position

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8. Problem solving
1. The fluorescein ring is too wide or too narrow
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Cause:
The fluorescein semi-circles are too wide.
The measuring prism was not dried after
cleaning, or the eyelids came into contact
with the measuring prism during
measurement. The pressure reading is higher
than the real intraocular pressure.
Correction:
Move the slit lamp back and dry the
measuring prism with a wad of sterile
cotton wool or lint free cloth.
Cause:
The fluorescein semi-circles are too narrow.
The lacrimal fluid has dried during prolonged
measurement. The pressure reading is lower
than real ocular pressure.
Correction:
Move the Slit Lamp back and ask the
patient to close his/her eyes once or twice,
then repeat the measurement procedure.

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8. Problem solving
2. The measurement prism does not touch the cornea or too much force has been applied
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Cause:
If the patient pulls his/her head back even
slightly, the pulses will become irregular and
measuring prism contact with the eye will
become intermittent. If the patient pulls his/
her head even further back, the fluorescein
semi-circles will completely disappear.
Correction:
If possible, use a band to hold the patient’s
head in place.
Cause:
If during measurement the slit lamp is moved
forward toward the patient or the patient moves
toward the slit lamp, the sensor arm will be pushed
into contact with a stop spring. The applanation
surface will be too large. The image will not change
when the measurement drum is rotated.
Correction:
Retract the slit lamp until regular pulses and a
correspondingly smaller applanation surface
are obtained. This is the correct measurement
position, in which variations in pressure
will not cause immediate variations in
the applanation surface.

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8. Problem solving
3. The two semicircles are not central in the field of vision
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Cause:
The reading in this position is considerably
higher than real ocular pressure.
Correction:
Using the slit lamp height adjustment
mechanism, lower the slit lamp until the two
fluorescein semi circles are equal in size.
Measurement pressure will then be reduced.
Correction:
Using the joystick, move the slit lamp up and
to the left.
Cause:
The rings are too far to the right.
Correction:
Using the joystick, move the slit lamp to
the right.