Detailed instumentaion and use of manual Lensometer and just a outline of automated lensometer. I have used the picture of manual lensometer with out the parts describtion because i have explained orally by showing the picture.. Hope u all like it and may help you in learning better. :)

1. LENSOMETERS
By :-
M.A.Rasheed,
Id:-12IMMO06,
I.M.Sc in Optometry & Vision Sciences,
School of Medical Sciences,
University of Hyderabad.

2. LENSOMETER:- It is a device
designed to measure the refractive power
prescription of a unknown lens.
(spherical, cylindrical with axis and also the optical center)
Types:- Manual & Automated
URL:- GOOGLE images/lensometers/html

3. Manual Lensometer :-
 Manual lensometer gives the accurate power of a lens and were
used in optical industries.
 A manual lensometer is portable and can be carried anywhere
 But a person needs to have a better idea to measure the power of
a lens. (specially in case of a toric lens)
Automated Lensometer :-
 It is a fully automatic well programmed device mostly used
in clinics.
 It is easy and faster and can print prescription.
 It is less accurate when compared to manual lensometer.

4. Manual Lensometer
URL:- GOOGLE images/lensometers/html

5. Steps to neutralize spectacle lenses in
manual lensometer
Calibration:- Adjusting the device to perform
smoothly in order to get accurate power of the
lenses.
Notes:-
 Eye piece should be focused manually.
 Power drum should level zero.
 All the knobs should be placed rightly and the device
should be neat and clean to avoid errors.
URL:- GOOGLE images/lensometers/html

6. Adjustment of Eye piece:-
• It is very important to focus the eye piece so that the observer’s eye is
relaxed and to avoid errors.
• In adjusting the eye piece the blurred black protractor is focused.
• At first the eye piece is rotated completely Anti-clock wise, the
protractor views blurred.
• Then slowly rotate the eye piece clock wise and stop at once where it
is sharp and clear.
• Now the eye piece is set and focused.
Blurred protractor Focused protractor

7. Placing the spectacle lenses on the device.
 Placing the spectacles lens on the device with its front surface facing
towards the eye piece.
There are 2 knobs on the
lensometer:-
1. Lens stop (holds the lens/frame
in place)
2. Frame leveling knob (makes sure
that the frame is leveled and
helps in accurate axis
measurement)

8. Target
It is green in colour and appears when the device Is
switch on.
It shows the position of the optical center of the lens.
There is a ring of round dots at the centre of the target.
This represents the power
orientation of the lens as it rotates
with the lens rotation
These round dots become small
lines oriented in one direction in
case of a toric lens

9. Analyzing the Spherical lenses
•Move the lens such that the target is exactly at the centre.
•Rotate the power drum until target is clear and sharp (all the
dots at the center should be separate & sharp)
•Stop rotating the power drum when the target is sharp for
the first time.
•Always count the upper mark on the power scale for
accuracy of the spherical power of the lens.

10. Analyzing the Cylindrical lens
The process of Neutralizing a toric lens when compared to spherical lens is
completely a different concept.
However, with the help of few tips we will be able to measure the lens
power very fast and accurately.
The key and the most important thing to remember is the central
orientation of the dots.

11. Process of toric lens neutralization :-
•Step 1:
Move the lens so that the target is at the center of the protractor.
•Step 2:
Rotate the power drum so that the central lines (oriented in one direction)
are sharp.
•Step 3:
Rotate the axis wheel so that one meridian of the target is parallel to the
orientation of the central lines.
Note that only one meridian of the target will be sharp
•Step 4:
Rotate the power drum so that the opposite meridian in the target is sharp.
Note that the central lines will change in direction and will be oriented
in the opposite direction.

12. Step 1:-
•Move the lens so that the target is at the centre of the protractor.
•This gives the optical centre location.

13. Step 2:-
•Rotate the power drum so that the central lines (oriented in one direction)
are sharp

14. Step 3 :-
 Rotate the axis wheel so that one meridian of the target is parallel to the
orientation of the central lines.
 Note that only one meridian of the target will be sharp.
 As the 180° meridian is sharp in this picture, we will write the power and the
axis as 180°
Ex: ---DC X 180s°

15. • Rotate the power drum so that the opposite meridian in the target is sharp.
• Note that the central lines will change in direction and will be oriented in the
opposite direction.
• As the 90° meridian is sharp in this picture, we will write the power and the axis
as 90°
Ex: ----DC X 90°
Writing the power
• As the Lensometer gives the readings of a toric lens power in 2 cylinder format,
we need to transpose the power and write in sphero – cylindrical format
• The power which we got in the example shall be written as:
-----DS/----DC X 180°

16. Important points to remember :-
 Always focus the eyepiece before using the instrument
 Concentrate on the central circular orientation of dots
(especially in case of toric lenses)
 One meridian of the target should always be parallel to the
orientation of central small lines (in toric lens)
 Each dot at the center will not be round, instead they will be
small lines oriented in one particular meridian
 Except the protractor, everything will be blur when a lens is
placed
 The target moves with the movement of the lens
Instrument should not be used more on battery

17. Automated Lensometer

18.  Automated Lensometer offers a fast and easy way to accurately measure all
lenses including: Single Vision, Bi-focal, Progressive, and Prism.
 Automatic measurements can be taken quickly by simply positioning the lens on
the lens table.
 Progressive lenses are recognized and measured automatically, with the rate of
addition and diopter change graphically displayed.
 Features:-
 UV transmittance measurement
 Pupillary distance measurement
 Measurement of soft and hard contact lenses
 Space saving vertical orientation
 Full color tilt-screen for easy viewing while standing or seated
 Easily accessible menu to customize your settings
 Data output options including a built-in printer and USB ports
 Can be configured to interface with EMR systems

20. References
URL:- GOOGLE images/lensometers/html
Few pictures are taken from lensometry manual by
Mr.Sunny Mannava (HCU).
THANK YOU
“Because eyes speaks a lot”