plus
and minus signs
SPH (Sphere) and CYL (Cylinder) values always have a
sign to indicate if they are plus or minus.
Occasionally
the ADD (Addition), written when the wearer needs an
additional strength in near spectacles, has a plus sign.
In
this example the Optometrist has written the signs above
the Sph & Cyl values.

i.e.
The right SPH is 1.25 and the right CYL is +1.50 


handwriting!
If you are unable to decipher the writing of the Optometrist
call them first to clarify the figures they have
written.
In
this example the left axis was given to us as 3u!. Sometimes
3s and 5s, 2s and 7s can be poorly written and difficult to
distinguish from one another.

The
left axis should be 30
(axis
are always a numerical value between 0 & 180) 


symbols
and abbreviations
DS is sometimes written to
denote sphere only. It can be ignored.
a
or ¥
symbols
are used in sphere boxes to indicate 'infinity'. The value
should be stated as zero.
Plano
is also used to denote the sphere
value is zero
Examples
of abbreviations...

The
right sphere is 3.00 and right cyl & axis are zero
The
left sphere is zero. 


Adds
Spectacle wearers over 45 yrs often need a different
prescription for distance viewing than for near.
The
difference between these is the add
or addition. The
difference only affects the sphere.
Sometimes
a different add is specified for viewing at 75100cm i.e. VDU
distance. This may be specified as intermediate
add. ('inter add' or 'INT add')
In
this example the optometrist has written the distance and near
prescriptions out in full rather than specifying just an add.

i.e.
The add is the near sphere minus the distance sphere = 1.50 


Other
prescription information
Prism is seldom used. It
is only used in spectacles when wearers have problems aligning
their eyes which may result in double vision. Prisms help keep
the image single.
Base
relates to the prism and can be up, down, out or in.
In
this example the triangular symbol used by the optometrist can
be ignored. The triangle only symbolises the unit that prism
is measured in.
BVD
or Back vertex distance is
sometimes specified for higher lens powers.
Any
other comments on the prescription should be noted.
You will have an opportunity to add any special comments when
you 'checkout' in the shopping cart

i.e.
The Right Prism is 1.5 and Right Base is UP
The
left prism is 1.5 and left base is DN (Down)
Back
vertex distance = 12mm



If
in doubt...
(
01925
357003
Telephone
support available 7days per week
(9am
to 5pm)

Alternatively
fax your prescription through
after
you have placed your order
to
01925 357113
or
email a copy of it to us
at email@safetyspecs.co.uk 