Buying Guides - Loupes
How to buy Loupes
Magnification enlarges items
viewed by the naked eye. This can be achieved by loupes
or operating microscopes. The advantage of loupes
is that they are more portable, practical and less
expensive. In order to choose the correct pair of
loupes, certain factors such as the magnifying power,
working distance, visual field and depth of focus
of the product should be considered. Here is a guide
to some of the key factors to consider when buying
loupes.
1) Choose your magnification
When starting out with your
first pair of loupes we suggest you start with a low
magnification, such as a 2.5X. This is because the
process of adjusting to loupes is made easier if the
magnification is lower, due to loupes with a lower
magnification having a larger field of view. With
a higher magnification the field of view is considerably
reduced. We would only suggest a higher magnification
to those who have worn loupes in the past and are
confident with a smaller field of view. The depth
of field is another factor to consider. This is the
viewing distance whereby the loupes remain in focus,
which in practical terms, means the distance you are
able to move closer or away from the patient, without
your loupes losing focus.
As a guide, for most microsurgical procedures in vascular,
cardiac and most plastic surgery procedures, 2.5X
to 3.5X magnification is usually sufficient, whilst
for nerve, tendon and digital vessel repair, higher
magnifications of 4.5X and 5.5X are often desired.
For general dentistry magnification, 2.5X is normally
used, although for endo/crown and bridge work, 3.5X
to 4.5X magnification may be required for better precision.
|
|
1.0X
magnification |
2.5X
magnification |
Generally speaking, for
lower magnification loupes (2.0X to 3.0X), use the
lighter Galilean design that consists of only three
lenses. For higher magnification loupes (3.5X to 5.5X),
a prismatic design is used which consists of a compound
system of several lenses and has superior optics.
However, due to there being more lenses in prismatic
loupes they have longer telescopes which make them
heavier and bulkier than Galilean loupes.
|
|
Galilean
design |
Prismatic
design |
For higher magnification,
an operating microscope should also be considered.
Click here
for more details about operating microscopes.
2) Measure your Working Distance
|
Working distance is crucial,
as this is the distance between the eyes and
the working site. Choosing the wrong working
distance can lead to poor posture, fatigue and
back pain as shown opposite. |
|
Correct
working distance |
Short
working distance |
|
Working distance can be determined easily by measuring the
distance between the eyes and the working site
using a tape measure. We advise that you do this
whilst in the sitting and standing positions and
than take the average measurement.
The working distance is also
crudely proportionate to height (see chart below).
Please note however, this only provides an estimate! |
 |
Working distance in relation to
height:
| Height |
Sitting |
Standing |
170 cm (5ft 7”)
170-190 cm (5ft 7”- 6ft 4”)
>190
cm (6ft 4”) |
340 mm (14 in)
420 mm (16 in)
460 mm (18 in) |
420 mm (16 in)
460 mm (18 in)
500 mm (20 in) |
3) TTL or Flip Up?
Basically there are two designs
of loupes: ‘Through the Lens’ loupes [TTL]
which have the telescopes fixed directly onto the lens
of the glasses, and ‘Flip-Ups’ loupes -
those where the magnification telescopes are mounted
on a hinge system attached to the frame. Flip-Up loupes
can be easily ‘flipped-up’ to allow the
surgeon or dentist to see through the naked eye or through
their normal prescription lenses.
|
|
Flip-Up loupes |
TTL loupes |
Comparison of Flip Up and TTL loupes
| Flip
Up loupes |
TTL
loupes
|
| • Cost less than
TTL loupes. |
• Cost more since customised
to user. |
| • Can be flipped
up when communicating with the patient or carrying
out routine tasks. |
• TTL’s lenses are fixed
to the frames. |
| • Flip-Ups can
be shared between colleagues, since adjustable.
|
• TTL’s cannot be shared
among colleagues |
| • Easy to change
lenses when prescription changes. |
• Should your prescription
change, the loupes must be sent back to the manufacturer
to be modified, incurring cost and inconvenience.
|
|
•
Heavier and more bulky.
|
• Weigh less and less bulky.
|
| • Narrower field
of view because the telescopes are mounted further
away from the eyes. |
• Wider field of view since
telescopes are mounted closer to the eye. |
4) Weight
Loupes must be comfortable
for the operator and therefore the weight of the loupes
is an important consideration. If the loupes are too
heavy they can be uncomfortable to wear - especially
during long procedures.
Loupes are usually mounted on spectacle frames and a
good quality frame will distribute the weight evenly
around the nose bridge and ears. Alternatively, loupes
may be mounted on a head band which although distributes
weight evenly around the head, does not protect the
wearer against splashes of fluid, as spectacle frames
do.
Summary
Choosing your loupes
is really down to personal choice, budget and intended
use. We hope this guide will help you make an informed
choice about your loupes.
Please go to the loupes
product page for full details of our product range
and to purchase products. At SJT Medical we are more
than happy to help you along the way, so please do not
hesitate to ask us for further information, or to arrange
for a free fitting by contacting us directly on Tel :
0844 272 1918.
|
