GENERAL DESCRIPTION
LUNDIE LOOPS
DESIGN
OBJECTIVES
This device is designed to provide a
comfortable and unobtrusive prop for those whose eyelids tend to droop or even
close completely. The prop is made in
the form of a large circle of stainless steel wire about the same size as the
spectacle lens so that the wearer looks through the middle of the prop. The upper part of the prop,
is fitted with a short piece of silicone tubing to give the necessary gentle
grip on the skin of the eyelid. The prop
is secured to the spectacles by drilling two small holes in the frame and
pressing the ends of the wire into them.
ADVANTAGES
OF THE PROP
-
It is comfortable to wear because it is silicone covered where
it touches the eyelids, it exerts only very light
upward pressure on the eyelid, with no pressure at all on the eyeball.
-
The gauge of wire used ensures that the pressure is firm enough
to hold the lid open securely, giving the wearer confidence to take part
in normal activities.
-
The prop is flexible enough to permit a degree of natural blink
to clear the eye of tears. This is not possible with
the eye taped permanently open, or the alternative rigid ptosis bar offered by some opticians.
-
It is safe because it has no sharp projections to injure the
eye.
-
The design is unobtrusive when worn because the prop can be
carefully formed to lie within the outline of the spectacle frame.
FRAME
FIT
It is important that the spectacle frame
should sit firmly and well up on the nose to resist the slight downward
pressure of the spring loop. The frame
side arms should also fit well, be properly shaped over the ears and
have a firm grip across the head to prevent the frame from sliding down the
nose. These are all matters which the
dispensing optician can take care of.
DRILLING
THE FRAME
The position of the holes in the spectacle
frame is not very critical, but they should be sited carefully and not look as
though they were drilled at
random. That is, the pair
on the left should match the pair on the right.
They should be located about 1¼ apart along the top of the frame (see
fig. 2) at opposite ends
of each lens aperture. These points,
near the hinge and nose bridge, are the strongest parts of the frame and are
not materially weakened by drilling. The
holes should be about control in the frame taking care to avoid the hinges and
concealed lens fastenings like the nylon cords used in some rimless
designs. The hole
centres are marked with a sharp scriber on the front face and drilled normal to
the frame using a No.66 (033) drill.
Four holes are drilled right through the frame, countersinking by hand
to the detail shown in figure 3.
FITTING THE FRAME
Hold the loop (still flat) against the
frame and shape the tails so that they pass over the centres of the holes that
have already been drilled in the frame.
Still holding the loop in place, slide the jaws of a small pair of
pliers over the first tail until the end of the jaws is in line with the hole
in the frame, grip and bend the wire at right angles. Push this tail into the hole and repeat for
the other tail of the loop. Check that the loop lies correctly in the frame to
satisfy the four conditions above, snip off the surplus wire and remove the
loop for finishing.
FINISHING THE LOOP
The component parts of the loop will now to
referred to as follows:-
LOOP – the full circle of wire carrying the rubber
sleeve at the top.
SIDE ARMS – The ends of the loop extending
from bottom point B to the fixing holes.
PEGS – The extremities into the fixing
holes.
To finish the pegs, set them to point
straight forward and touch them on a grinding wheel until the length of each
one matches the thickness of the pegs with a smooth file and set the tip
downward with
crimping pliers as shown in figures 3
& 4.
Now set the side arms forward an equal
amount, about I, holding the loop at B. The side arms should have a very slight
curvature as shown in Figure 4 to ensure that the side arms and loop stand
clear of the frame at the bottom and do not jam in the corner between the lens
and frame.
Assemble the loop to the frame, pressing
the pegs into the holes using pliers with leather between the jaws to avoid
scratching the frame.
The final test is to press down on the loop
at point A when it should be perfectly free to move up and down about ½ , the wires sliding sweetly over each other without
jamming on the frame or nose pad.
When fitted in the frame the loop is
surprisingly difficult to deform, but minor alterations to suit patient may be
carried out by moulding it in position on the frame. Major alterations, such as a change of height
or loop Diameter, are test performed off the frame, working from the basic
shape shown in fig.4. otherwise serious distortion will creep in and make the loop un-wearable.
ADJUSTING TO THE WEARER
Figure 5 is a diagrammatic side view of the
loop in position on the wearer. The loop
is set to stand away from the spectacle frame by about ¾ at the top. This makes it bear very lightly on the upper
eyelid, lifting it into the space above the eyeball. It should not bear upon the eyeball in any
way as this would be very painful, so care must be taken not to pull the loop
too far away from the frame.
To get the right amount of lift, the loops
should be depressed with the middle finger of each hand when putting on one’s
glasses, so that when on position on the nose, the lids will open when finger
pressure is released.
|
