Spot Retinoscope Conversion Part Available from Bernell

Spot Retinoscope Conversion Part Available from Bernell
For far too long we have not been able to purchase a true spot retinoscope. Now you
can….almost!
First a little background. For many years we have been teaching as a core part of the
Art & Science of Behavioral Optometry course that is part of the OEP Clinical
Curriculum stress point retinoscopy. We spend a good bit of time with this and work
to help people learn this valuable technique. I even made some video recordings so
that course attendees would have a good idea of what to look for through their
scopes. I knew that spot scopes were hard to come by but was told over and over
that people could simply get a spot bulb for their streak scopes and all would be good.
However, time after time at a subsequent course the instructors would be asked to go
over that stress point retinoscopy once again because they were having trouble
implementing this new activity. After a period of time I asked one of these
optometrists to bring their converted scope to me. Well I tried the technique, which I
have become very proficient at and lo and behold I had tremendous trouble doing ti
and seeing what I needed to see.
The key point is that the converted streaks ended up with far too narrow a beam of
light and the light was very uneven. This made it nearly impossible to keep the light
centered in the pupil and steady, a prerequisite for doing this procedure and variations
in the light were not fully attributable to changes the person was making. Thus, the
resultant that doing the procedure in a way that would yield consistent and reliable
data was next to impossible.
That started me and others on the road looking for a true spot retinoscope and you
guessed it, we kept coming up empty at every turn. We would go through exhibit
halls at meetings finding all the hand instrument companies and the picture got
bleaker and bleaker. No one was making a true spot anymore and none had plans to
do so.
To make a very long story a little shorter I convinced Craig Andrews at Bernell that
we desperately needed his help and that if we could make true spot scopes available
again that optometrists would indeed purchase them.
In the early summer of 2010 I sent to the chief machinist for Bernell my Welch Allyn
spot scope head for reverse engineering. I had disassembled the head and discovered
that the plastic top part of my spot and the plastic top part of the streak of the same
vintage were one and the same. Welch Allyn representatives had laughed at me when
I asked them about making the spot head again. They said that the molds for the
plastic parts were gone and that no more could be made. But knowing that there are
tens of thousands of the Welch Allyn streak scopes in the wild, most of which are
gathering dust triggered a thought.
What if we could get the key part made?
Above is a picture of my original Welch Allyn part on the right and the replacement
part made by Bernell on the left. This is the key part and it is now available from
Bernell.
So here is the key. You need to find an old Welch Allyn streak head so that you can
scavenge the plastic top part that has the mirror in it. Here is what that part looks
like:
This part is exactly the same on the original spot and the streak of the same vintage.
Here is a picture of the streak scope head you want to find:
You can separate the plastic head from the base by gripping the base securely and
rotating the knurled ring just below the plastic. The plastic part is gold. The streak
part can be stored or disposed of. 
You can then order the part from Bernell, assemble it by inserting it into the plastic
head and then putting in a Halogen bulb (also available from Bernell) and voila you
have a classic spot scope, good as new. Actually, the machinist made a few minor
improvements in that he made the aperture slightly larger so the beam when it hits the
face is a little bigger than my classic scope.
Now as if that wasn’t good enough there’s more! BTW, full disclosure….I have no
financial interest in the scope….I do have a HUGE interest in everyone being able to
see what they need to so they can be the best optometrist they can be but I have no
direct financial interest in this product.
On the road to working out how to do video instructional recordings I found that
with a minor modification to the hole in the back of the scope I was able to do a lot
more. So the first thing you can do is to simply unscrew the dust cover on the back
of the plastic head. See below for a direct comparison.
The head on the right has the dust cover still in place. The one on the left has the
dust cover removed. Good but not good enough. Take a look below:
The head on the right is the standard plastic head with the cover plate off. The one
on the left is one I drilled out to 13 mm to enable the videotaping. Once I had this
done I realized that (1) I was able to be much more stable with the scope because I
could see much more space through the scope and (2) I could easily scope with both
eyes wide open all the time because with more volume seen through the scope it was
very easy to fuse the world through it.
Now there’s a huge caveat. The opening is right up against the mirror. Drill without
the head being fully disassembled and you will most likely ruin the mirror. The
disassembly is not for the faint of heart. I almost ruined one head figuring it out. If
you want a bigger aperture (and yes I know you have to clean it out a bit more often),
Bernell is also offering a drill out service done by their expert machinist.
You can use the original just fine but I would suggest getting the head you will used
drilled out to anywhere from 8 mm to 12 mm. If you only want the insert part you
can get them right away. If you want the drilled out head you will have to send that in
and leave a couple of weeks for that work to be done.
I am so glad that we now have available again a true spot retinoscope.
Paul Harris