Cleaning Phoroptor Lenses

[Energy Conservation in Housing]

Cleaning Phoroptor Lenses
by David L. Meinert, O.D.

It is possible to clean lenses inside a phoroptor using no
instrumentation other than standard "Q-tips"** and a lens/glass
cleaner solution (such as Glass Plus™)
The method is to expose individual lenses in the phoroptor opening,
so they can be cleaned on both sides. On both the right and left side
of the AO/Reichert/Leica Ultramatic Rx Master phoroptor

There are 10 surfaces or lenses on the auxiliary lens wheel.
There are 11 sphere lenses in 3.00 D increments.
There are 11 sphere lenses in 0.25 D increments (the labeled powers:
-.25, -.50, -.75,-1.00, +.25, +.50, +.75, +1.00, +1.25, +1.50,
+1.75)
There are 8 individual cylinder lenses.
(the labeled powers: 0.25, 0.50, 0.75, 1.00, 1.25,
2.50, 3.75, 5.00)
There is the Jackson Cross Cylinder.
There is the Risley prism assembly.

This makes for 42 lenses per side of the phoroptor to be cleaned (a
total of 168 surfaces to be cleaned per phoroptor). I have found that
for a phoroptor having had full-time use for 8 months or longer, a
complete phoroptor cleaning can be done in about 3 to 4 hours time,
unless running into complications (see warning below) or very dirty
phoroptor lenses.

Warning: Cleaning phoroptors can have complications. It is possible
to dislodge lenses, while cleaning a phoroptor. (Even with the force
exerted by a Q-tip, it is possible to dislodge phoroptor lenses.) Such
an event could require disassembly of a phoroptor before further use,
since a lens out of place could jam the phoroptor mechanism. Or a
dislodged lens may make it necessary to send out the phoroptor for
repair. Having a spare phoroptor on hand is a good idea, in case a
lens becomes dislodged during the cleaning process.
The attached pages show procedures for cleaning phoroptor lenses –
based on my experience so far in cleaning up to 100 phoroptors, per
year, for 10 years.

** Standard Q-tips, means the paper stick type. Sticks made of
plastic tubing typically have so little rigidity that it is sometimes
difficult to clean lens surfaces that are not exterior. (While trying
to clean lenses more internal to the phoroptor, the plastic stick
versions bend too easily -- and were therefore harder to use.) The
sterile wooden stick Q-tips often used in clinics also do not work
well, perhaps due to wax used in the manufacturing process. The
actual Q-tip® brand has a thicker amount of cotton on the tip than
generic brands and has a slightly stiffer paper stick than some lower
cost generic versions of "Q-tips" that had paper sticks. Sometimes
the extra thick cotton of the Q-tip® brand seemed to speed the
cleaning process, due to its larger surface area. Other times the Q-
tip® brand seemed to make things more difficult since it is easier for
the large tip to snag on metal edges inside the phoroptor, causing
more lint, or catching smears of oil or glue from the edge of lenses.

An alternative way to clean phoroptor lenses is during disassembly. I
found a fairly good way to clean the sphere wheels when disassembled.
What I needed was a surface to place the two sphere wheels on, during
cleaning. What I was found was a specific size of plastic (Melmac)
kitchen plate, which was just the right size so that the rim of the
lens wheel was supported by the plate, but the lubricated area of the
bearings was well above the surface of the plate. This allowed me to
clean the lenses, from edge to edge without disturbing the grease from
the bearing area. After re-assembly, what I typically find is that
the lenses still need further touch-up after this cleaning method.
Typically the lenses will look “clean” with light reflecting from the
lens surface. However, with the phoroptor re-assembled I could detect
additional optical filming, not obvious while disassembled. With
light shining in from an angle, through the lens, optical defects were
much more obvious than by reflection alone. For me, the main value of
cleaning while disassembled is to remove larger quantities of dirt /
debris, without introducing additional lint from the cleaning
process. I can clean the lenses quicker, jumping from lens to lens,
and the lens surface dries out faster as the entire sphere wheel is
exposed to room air.

Cleaning Phoroptor Lenses

Equipment:
Standard Q-tips (packet of 300 or more is fairly economical)
Lens/glass cleaning solution (Glass Plus, or equivalent works well)

Procedure:
A. Set-up
1. Remove and clean the plastic face shields (scrub with a soft
toothbrush, if necessary), and set aside.
2. Shine the (60 watt) stand light, so that it shines through the
phoroptor openings, from the doctor side, while you look through the
patient side of the phoroptor. (The stand light can be positioned as
close as 6 inches from the phoroptor lens opening.)
a. The idea is to have the lens lighted indirectly, without shining
directly into your eyes – so the light should be slightly off to the
side.
b. It is useful for better contrast to have the rest of the room
somewhat dark (beyond the light source).
c. If you are presbyopic, it can be useful to wear a single vision
magnifier lens, to make the equivalent of up to a +4.00 or +6.00 Add.
(For example, I am a -2.50 spherical myope, presbyopic; I typically
wear a +3.25 OTC reader while cleaning lenses. This is nearly a +6.00
add effect.)

B. Warnings
1. Be very gentle with the "Polaroid" lens, since it is the most
fragile and most easily dislocated (other auxiliary lenses can also be
accidentally dislocated). Typically I support the Polaroid lens (and
other auxiliary lenses) with one Q-tip, pushing from the DOCTOR side
of the phoroptor, while I clean from the patient side. (The Polaroid
is a thin plastic lens, and could be easily scratched as well.)
2. It is possible to dislodge other phoroptor lenses, even with the
fairly mild force exerted by a Q-tip.

C. Procedure:
1. Clear the phoroptor so no lenses are exposed.
2. Wet a Q-tip end, by dipping in a dish of Glass Plus. Blot the Q-
tip against a cloth, if necessary, to remove excess moisture.
3. Start with the Auxiliary lens wheel, by cleaning the occluder
surface and dry with the opposite (dry) end of the Q-tip. (Q-tips are
cheap; throw each away after use on one lens.) Repeat the procedure,
if one wiping of a lens is not sufficient to clean it.
4. Finish all the auxiliary lenses, cleaning both sides of the lenses,
when necessary. If the lens appears fairly oily or filmy, a second or
third Q-tip (one end wet and one end dry) could be needed for complete
cleaning.
5. If excessive lint is visibly left on the lens surface, blow off
with one of the lint removing methods, as listed on pages 5 and 6.
6. Then clean the 11 lenses of the strong power sphere wheel (3.00 D
increments)
7. Then do the 11 lenses of the 0.25 D sphere wheel
(the labeled powers: -.25, -.50, -.75,-1.00, +.25, +.50, +.
75, +1.00, +1.25, +1.50, +1.75)
8. Cleaning cylinder lenses can require more care, due to the
possible presence of oil near the outer edge of the rotating lens
surface. See page 5 describing cleaning of cylinder lenses.
9. Repeat the procedure for both the (patient) right and left side of
the phoroptor.
10. For you to visualize the entire lens surface, it can be useful to
move the lens up and down by manipulating the lens-control wheel
during cleaning – such as for cleaning sphere lenses. To view the
lateral aspect of each lens during cleaning, you can rock slightly
from side to side.
11. When cleaning cylinder lenses, the entire lens surface can be
visualized while rotating the lens during the cleaning process.
12. Depending on the humidity level when cleaning phoroptor lenses, it
can take a lot of wiping to soak up the lens cleaner solution. It can
somewhat speed the cleaning process to have a fan blowing air slowly
toward the phoroptor. That way, when wiping the lens dry, evaporation
speeds up the lens drying process.

D. Clean the (JCC) flip cross-cylinder lenses. (If unusually
difficult to clean this lens with Glass Plus, due to grease or glue
around the lens edge, using alcohol might help with the cleaning.
However, alcohol can also soften up the glue securing the JCC lens.
Such an event would require a time-consuming re-gluing of the lens, on
axis.

E. Clean the outside of the Risley prism.

F. Cleaning the inside surface of the Risley prism is more
difficult.
You can reach the lens surface from the patient side by inserting the
wet Q-tip all the way through the phoroptor, and then drying the
surface with a dry Q-tip. Make sure the Q-tip is NOT dripping wet as
moisture can work its way between the Risley prisms, and you will be
unable to clean it. Similarly, cleaning the surface with alcohol can
allow the alcohol and vapors to get trapped between the Risley prism
surfaces.
The internal parts to the Risley prisms CANNOT be cleaned without
disassembly, and resultant loss of calibration. So, you can clean the
inner and outer surfaces of the Risley prisms, and it can still look
notably filmed over. That’s the best one can do without disassembly.
Such Risley disassembly (when needed) is best if sent to optical
experts, such as LOMBART instruments. Sending the cylinder assembly
can be done instead of shipping the entire phoroptor.

G. Finishing touches:
Do a quick re-check of all the previously cleaned lenses. It can be
surprising how lenses that seemed clean, were not actually completely
dry. If you go back and re-look at each lens, one can find a number
of the lenses now have some visible filming or smears not previously
seen. Such a re-touch-up of lenses can often be done with a dry Q-
tip.

H. Replace the plastic face shields on the phoroptor.

I find that for a phoroptor having had full-time use for 8 months (or
longer) it takes 3 to 4 hours to complete the cleaning process --
unless running into complications, such as oil or glue getting smeared
onto a lens surface -- or a dislodged lens from the phoroptor. Longer
time is typically needed if the phoroptor lenses are unusually
dirty.
It is possible to dislodge a lens from a phoroptor, due to excessive
pressure used in cleaning the lens surfaces, or due to insufficient
adhesion of glue used in the manufacturing process. Re-gluing a
dislodged lens will likely require disassembly of the phoroptor in
order to expose the areas to be glued. (A Polaroid lens and some
other auxiliary lenses can potentially be re-glued WITHOUT disassembly
of the phoroptor. The Polaroid lens has to be re-glued on the proper
cancellation axis, so that it functions for Polaroid testing.) I have
written a several page narrative on disassembling phoroptors, which
can be useful if planning to re-glue phoroptor lenses.
In cleaning more than 100 different phoroptors each year, over the
past 10 years, I have had some lenses dislodge from the auxiliary
wheel, from both of the sphere power wheels, and a few cylinder lenses
dislodged as well. AO/Reichert/Leica expects the bonding of some
auxiliary lenses to be somewhat fragile. Other lenses in the
phoroptor might dislodge due to insufficient factory bonding of the
lenses. For the CYLINDER lenses to be re-glued, I typically returned
the lens (and the cylinder housing assembly) to Lombart instruments
for the lens to be re-glued in the proper axis position. On two cases
the lens dislodged from the plastic cell to which it was glued. On
another case, a cylinder lens cell dislodged (apparently a retaining
clip broke for the cylinder cell), while the lens remained glued
inside the lens cell. There is a method to re-glue dislodged cylinder
lenses, by getting them properly aligned on axis. I have devoted a 2-
page narrative to this fairly complicated procedure.
Spherical lenses, such as from the 3D sphere wheel can have excessive
amounts of glue, used to bond the lens in place. The glue is easily
picked-up during cleaning, and smeared onto the lens surface. It is
possible to clean off the excess glue from the lens periphery by using
solvents, such as "Goo Gone" and isopropyl alcohol. Put Goo Gone on
the Q-tip, and thoroughly wipe around the lens edge, which slowly
loosens the excess glue. It seems helpful to blow-dry the Goo Gone
(and alcohol) with a compact hair dryer (see page 6), then clean with
Glass Plus and wipe dry with a Q-tip. For large accumulations of glue
or other sticky deposits, additional cleaning of the lens edge with
isopropyl or ethyl alcohol on a Q-tip can be useful. After cleaning
off the Goo Gone and alcohol, if the lens surface is not fully clean
yet, repeat cleaning with Goo Gone and / or alcohol until the excess
glue is removed. Finally clean the lens with Glass Plus.
In cleaning over 100 phoroptors, I have on occasion run across lenses
that will not fully clean; often such lenses have the appearance of a
"spray" or persisting film pattern on the lens, and no solvent seems
able to remove the "debris." By examination of the lens surface with
a slit lamp, I was able to determine that these defects are due to
fine pitting or other distortions on the lens surface, presumably
manufacturing defects. Fortunately, these defects show up mainly with
bright indirect lighting, as used during lens cleaning, and the
optical defects of one lens does not cause any significant problem
during eye exams.
If transporting phoroptors in cold weather, it is a good idea to warm
up the phoroptors before placing them back in service in an exam
room. I have found it helpful to bring along a compact hair dryer and
blow it through the lens openings, while quickly shifting the lenses.
(Rotate the cylinder lenses around, rotate the 3D sphere wheel around,
rotate the auxiliary wheel around, and rotate from 0 to –1.00 sphere
and 0 to +1.75 sphere.) Repeat this process if the lenses / phoroptor
didn’t heat to room temperature in the first run through the lenses.
The heat put out by the hair dryer will quickly raise the temperature
of the cold lenses, and it will prevent moisture from condensing on
the otherwise cold lenses.

Cleaning Cylinder Lenses

Problems can occur when cleaning cylinder lenses (in phoroptors).
Some grease or oil has been placed near the cylinder lenses, to allow
them to rotate. If there is excess oil, and this oil is picked up by
the Q-tip, while cleaning, it can smear over the lens surface, and can
sometimes be hard to clean off the lens.

Cleaning procedure for cylinder lenses with excess oil.
A. Clean a peripheral path on the lens (start with the 0.25 D cyl
lens).
1. Moisten a Q-tip with Glass Plus; blot any excess fluid on a cloth
2. Hold a Q-tip gently and steadily at the outer edge of the lens,
while rotating the cylinder lens (2+ rotations). Sometimes alcohol on
the Q-tip gets the grease better.
3. Repeat as necessary with fresh (moist) Q-tip ends until minimal oil
comes off on the Q-tip (discard used Q-tips). Using this procedure,
doing step #2, once on the front and once on the back of the lens edge
may be sufficient if no obvious oil is evident; with much oil, it
could take several Q-tips to clean off each side of the lens edge.

B. Clean mid-periphery to center of lens
1. Moisten a Q-tip with Glass Plus; blot any excess fluid on a cloth
2. Wipe a Q-tip from mid-periphery of lens to center, using tiny
strokes, while rotating the cylinder lens continuously.

C. Wipe the lens area dry
1. Hold a dry Q-tip gently and steadily at the outer edge of the lens,
while rotating the cylinder lens (2+ rotations)
2. Wipe a dry Q-tip from mid-periphery of lens to center, using tiny
strokes, while rotating the cylinder lens continuously

C. Repeat A, B, and C (above) on the inside lens surface, as well as
the outermost lens surface.

D. If necessary, repeat procedure for each of the 8 cylinder lenses in
each bank.
(0.25, 0.50, 0.75, 1.00, 1.25, 2.50, 3.75, 5.00)

This procedure should give nearly edge to edge cleaning of cylinder
lenses. With minimal oil on a lens edge, it could take as little as
one minute per cylinder lens – using this cleaning technique. If
persisting amounts of oil are present, it could take more than 15
minutes per cylinder lens.

Lint from Q-tips: It is possible to introduce a fair amount of lint
during cleaning, using Q-tips. I have found it sometimes helpful to
give a firm “blow” (by mouth) on a dry Q-tip before using it to dry
off a lens surface. This seems to reduce the lint introduced during
cleaning.


Optional equipment items:
Soft cleaning cloth (I found a single-layer diaper cloth works well)
Small blowing device (to remove lint) and/or a compact hair dryer
- a compact/travel hair dryer, such as the 400 Watt Travel dryer made
for Franzus (1-800-706-7064) or CVS Pharmacy (CVS, c/o Woonsocket, RI
02895). Current cost about $10 to $15. I also saw a similar
appearing compact hair dryer sold by American Tourister
- or a rubber bulb designed for rinsing out "ears"
- or a miniature "turbo-vac" device, but used in the blowing mode
- or a small can of compressed gas for cleaning (probably available
from Radio Shack stores)
Goo Gone (a liquid cleaner)
Ethyl or Isopropyl alcohol
Small dish to hold the lens cleaner

Anti-Reflection Coating Problems
Starting around the year 2000, Reichert began putting anti-reflection
coating on the glass lenses inside the phoroptor. (By comparison,
Marco and Topcon appear to use primarily plastic lenses with anti-
reflection coating, making the lenses even more fragile and prone to
scratches and damage to the lens itself.) Depending on the quality
of the coating it sometimes made little difference in cleaning the
phoroptor lenses. By phoroptors made in 2006, I found the quality of
the anti-reflection coating was more fragile and of poorer optical
quality, and made some lenses extremely difficult to get clear. The
coating added a whole additional level of optical distortion to
phoroptor lenses. Historically, lenses used in phoroptors can have
defects in optical clarity. With the large number of lenses used in
phoroptors, it is not unusual to have a few defective lens surfaces in
a phoroptor. With the addition of anti-reflection coating, it more
than doubles the chance of such defects being present. Furthermore
the anti-reflection coating does not clean off as easily, and the
slightest amount of debris on the lenses becomes optically more
obvious with anti-reflection coating.
In 2011, I cleaned several phoroptors built by Reichert in 2009.
These phoroptors had defective anti-reflection coatings, surfaces I
found much more difficult to get clean than the conventional glass
phoroptor lenses. A couple lenses on one phoroptor had extreme
distortion on one surface of the coating, a sort of cracked
appearance, covering the central half of the optical area. No
solution seemed able to clean it off. As with some other defects, the
optics sometimes appears to clear up while the cleaning solution is
applied, but once the lens is wiped dry, the defects return. As I
persisted in trying to clean off the distorted areas of the lens (anti-
reflection coating), it seemed to change as I was cleaning the
surface. Alternating between Goo Gone and alcohol, eventually I
dissolved the debris off the central area of the lens. However, this
process took 3 hours to clean off the anti-reflection coating from one
side of these two lenses. It was hard to say which solution was
removing the coating. For best outcome, I had alcohol on one side of
the q-tip and Goo Gone on the other side, and repeated this process
for hours. I kept applying new solution, and new q-tips. I quit the
“cleaning” process when I had cleared about a 14 mm central zone of
the 20 mm lens. (When I was done, the lens looked similar to a PMMA
contact lens that was a “blended bi-curve” zone. The central 14 mm
was clear, and then there was a hazy area where the coating was half
removed, then a clear area in the extreme periphery, where the coating
persisted.) It was an extremely tedious process, and I felt fortunate
that the glue (holding the lens in place) did not dissolve during this
lengthy process. I felt the peripheral distortion was preferable to
the original central distortion, but was a dreadful process to get
there.
It is my impression, that a regular glass lens phoroptor that is
fairly heavily used can take 3-4 hours to clean all the lenses. By
contrast, a phoroptor with poor quality anti-reflection coated lenses
can take much longer, six or more hours, unless running into problems
like I cite above with lens coatings that are extremely distorted.
I usually start phoroptors with cleaning off the external surfaces,
cleaning the JCC mechanism (so it operates more smoothly), and
cleaning the internal surfaces of the phoroptor body and lens wheels.
While inside the phoroptor, I make sure moving parts move smoothly,
and do any additional lubrication needed. It commonly takes me 2-3
hours per phoroptor, BEFORE I start on the optics. Then another 3-4
hours on the optics. When phoroptors are unusually dirty inside, I
find it useful to clean the phoroptor lenses (mainly the sphere wheels
and lenses) while disassembled. Yet I always re-check (re-clean) the
phoroptor lenses once the device is reassembled. Lenses that look
clean (by reflected light) when the phoroptor is disassembled can look
notably filmy when viewed reassembled with light shining sideways onto
the lens surfaces.

Related Phoroptor data

Disassembly of the phoroptor is periodically needed to clean the
phoroptor internally, to re-lubricate internal moving parts, to
replace worn-out internal parts, or to re-glue dislodged lenses.
Write or call Leica Microsystems, 3374 Walden Ave, DePew, NY 14043,
phone (716) 686-4500, to get a phoroptor parts manual if any
replacement parts are needed for the RxMaster phoroptor.
(www.reichertoi.com) Actual ordering of parts can be done through
instrument suppliers, such as Lombart instruments (1-800-LOMBART).
Per data I received from Leica Microsystems in November 1999, the
following describes glue used in Leica/Reichert/AO phoroptors. These
statements I am quoting from the letter I received from Leica.
"Cements used in Phoroptor Refractor
1. Kodak Optical Cement HES-1 is used for bonding lenses to metal.
This cement requires baking to cure.
2. Hysol RE 2038 with HD 3404 is used to bond cylinder lenses to the
plastic cells.
3. Tacking cement for cylinder lenses is made by dissolving clear
acrylic plastic in MEK."

Of course, those directions did not simplify anything, since I do not
have any details on the source of the glue in statement 2. Nor do I
presently know what "MEK" is (statement 3.) I'm sure the Kodak
company could supply the HES-1 glue and instructions for "baking" the
glue in place. It just seems that "baking" glue in place is a little
beyond the scope of "in-office phoroptor maintenance."
I have found that a quick-setting (5-minute) epoxy glue works well to
re-bond dislodged lenses. Mix the two parts of the epoxy glue and
apply tiny amounts of the glue around the lens well, where the lens is
to be secured (such as by using a tiny screwdriver tip to touch small
amounts of the glue inside the lens well). Hold the lens in place
while the glue is setting, usually 15 minutes time, or even up to ½
hour. Clean off any excess glue with alcohol and then use Glass Plus
to finish cleaning the lens.
For cylinder lenses, alignment is most critical. When I had cylinder
lenses dislodged, I previously sent the partially disassembled part of
the phoroptor (sending just the "cylinder housing assembly" and the
dislodged lens) to Lombart for re-gluing. It cost $75 (plus shipping)
for one cylinder lens to be glued back in place, as of June 2000. For
details on how YOU CAN re-glue dislodged cylinder lenses, see the
separate 2-page narrative on this subject. But to be safe – simply
send the cylinder lens and cylinder assembly out to be serviced.

Cleaning phoroptor lenses is a tedious, typically monotonous
process. If doing it for just a few hours, it can be tolerable. If
doing it for hundreds of hours per year (as a part-time job), it tends
to make one go “stir crazy.” Playing radio music in the background
can help, but even music can get old. I have found it helpful to play
(previously viewed) movies or TV programs in the background, such as
by use of a compact TV/VCR/DVD player. That way, a story / plot can
occupy one’s mind while the eyes and hands are busy with lens
cleaning. Since I have hundreds of hours on DVDs of my favorite
science fiction programs and other movies, I tend not to dread
returning to hours on end of phoroptor cleaning.
To allow me to clean phoroptors at home, I constructed a stand, made
from 2x4s and plywood to hold the phoroptor and to hold a small lamp
(to shine through the lens openings). I designed the stand to be
placed on a tabletop. I use a specific size & diameter of a bicycle
seat post as part of this stand, which serves to hold the phoroptor (I
believe it is a Schwinn-style post, about ¾ inch diameter and 15
inches long). I rigged the light source to be able to slide along the
post, to shift the light source when I move from cleaning the right
bank, to the left bank. With this phoroptor stand, I can clean many
phoroptors per year, in my spare time at home. Having one or more
loaner phoroptors to shift around to exam rooms, allows one to clean
phoroptors off-site, without the time constraints of clinic operating
hours.