lensometry is a formula in which lens power and been measured and are checked using forms. The first three steps that must be performed on an automatic lensometer (regardless of manufacturer) are: [2] Position the lens to be measured on the specific table or platform of the lensometer. Start with the power wheel at a very high plus power. Turn the power wheel to reduce plus power, while turning the axis wheel, until a set of mire stripes (the perpendicular crossed lines) come into focus and the bars appear straight and unbroken. Refine the axis and power wheels until the set of stripes is very sharply focused and unbroken. In general, it is a simple rule that before placing a lens on any lensometer, look at the lens visually 16 inches from your face and move the lens around to see if there is a bifocal in the lens. Progressive lenses are often hard to see; you should be able to recognize this before reading the lens power, otherwise a lensometer reading may be off.

3. Half-silvered mirror
{beam splitter)
'"
8D Badal lens
Spectacle Plane
=Anterior focalpoint of eye
=secondarv focal ut of Badal lens Adjwtable Stigma w ith
Diopter scale

4. 1. OnfOff S vl lt c h
2. Pllol Ugt it
3. Foc:uUbte Eyeoplec•
4 . L41tu Sto p
S . L.en Holder
6 . E ' / G P I - Focuit1 P o si11on S c.alo
7. LeneTebte
8. l o " - Tabla A d jLl$tmont Knob
9 . AJCl9 WheeC
1O. f>
ower Wh!JGI
11. Auidllary Prialn Holder
12. f>
f ism Ol tion RJn51
13. Ink Mqiitiiflg Systipm
14. Ma r ld n g P ina
1S.I
n k Well

6. Description of the Lensometer
1.The Eyepiece : mounted in a screw-type focusing mechanism, the eyepiece plays
an important role in the accuracy of your readings. It is essential that the eyepiece be
focused to the individual eye of each user. It may be fitted with a rubber guard to
prevent scratching of the user 's own eyewear.
2. Chro111e Knurled Sleeve: used to rotate the Reticle to orient prism base.
3.Pris1
1
1 Co1
1
1pensating Device Knob: Used to read prism amounts greater than five
prism diopters.
4. Lens Holder Handle :Used to hold a lens in place against the aperture.
5 . M arking Device Control: Used to spot the lens at either the Optical Center or
Prism Reference Point (PRP).
6. Gi1
1
1bal: A pivoting holder that holds the lens in place.
7. Ink Pad: Holds the spotting ink.
8. Spectacle Table Lever: Used to raise, or lower the level of the Spectacle Table.

9. Optics of Lensometer (Manual)
Ull!im
• • cwa
V tlNll• IQ telesc wope /
Spectaote s
10
R g . 1 : z . 1 5. Sctn>mauc d: agr:am of t h e o p cs of a qrp11e.al Botdal len
0

11. 0 ." E ) f©
- ·
·
s
. - - --F
. ...._:::_..,.'
•
FIG . 8.B

16. Cylinder
• Algebraically addthe nu,
mber shown
now on the power wheel W1
ith the
number previously recorded as the
sphere, this is the cylinder amount,
record the axis
• To tran pose the cylinder, rotate the
axis 90 and start over