Prosthetic Eyes Presentation by Fred and Rick Miller re: Alberta

Prosthetic Eyes Presentation
by Fred and Rick Miller
re: Alberta Opticians Convention 2014
Experts panel presentation
I am here today to discuss prosthetic eyes. In our practice in Lethbridge my father Fred Miller
and I help patients who have suffered birth defects, disease, and injury of their eye or eyes. My
father is the real expert (he has been fitting prosthetic eyes for the last 50 years) but
unfortunately he could not attend today, so I was roped in by Belinda to attempt to fill his very
large shoes. I will try to do my best but if you have any questions feel free to ask me after the
panel and I will attempt to answer them or I will ask him and get back to you with an answer.
Patients come in to us or are often referred by Ophthalmologists for a variety of different
problems. If their eye is still intact but disfigured, for example aniridia, albinism, amblyopia,
colobomas, cataracts, corneal leukomas, diplopia, injuries, and birth defects or disfigurements
we can fit them with prosthetic contact lenses, which is more my department. Some fittings are
relatively easy and sometimes we can use stock tinted or opaque lenses from regular suppliers
like Alcon or Cooper, sometimes we need to use more custom lenses to suit their needs (See
figure 1).
Prosthetic contact before
Prosthetic contact lens after
(Figure 1)
pg.2
I use a very skilled lab from Vancouver who does a lot of work in the movie industry, if you have
seen a monster, or a gory eye in a movie chances are they have probably done the contact
lenses for it. Sometimes we are working with a sighted eye as in aniridia, albinism or amblyopia
and diplopia, and we use a black pupil or a black or opaque iris to block light or occlude, but
most often we are working on unsighted eyes to give a more pleasing cosmetic appearance.
If a patient's cornea or sclera has atrophied or sunk too much to allow a contact lens fitting then
we fit what is called a cosmetic shell which is similar to the old pmma scleral lenses fit in the
very beginning of the contact lens era or the mini scleral's being used currently. The difference
is, the scleral shell rather than being clear is painted to resemble the unaffected eye, with a
white sclera with vasculature, colored iris and black pupil. The shell is put in place over the
patients existing sclera and cornea to mask flaws and match the companion eye (See figure 2).
Prosthetic shell
(Figure 2)
If the patient no longer has a cornea due to evisceration, or if the eyeball has been completely
removed from the orbit, as in enucleation than a prosthetic eye is used. Most times after
enucleation surgery an ocular implant is inserted into tenon's capsule by the surgeon. The size
of the implant is crucial, if it's too small it can cause migration, exophthalmos or a deep sulcus.
Too big and it can cause erosion, implant exposure and infection. The optimal size is for the
implant to make up about 65-70 percent of the volume of the lost eye with the ocular prosthetic
making up the remaining 30-35 percent. In evisceration the sclera and its extra ocular muscles
remain intact, in enucleation the extra ocular muscles are attached to an implant.(See figure 3)
pg. 3
cross section of implant
(Figure 3)
(photo courtesy of AMA)
In both cases ocular motility remains so the prosthetic eye moves in unison with the unaffected eye. In
rare cases the extra ocular muscles cannot be attached to the implant which results in limited or no
motility.
There are several different types of implants used such as: the acorn, peg, round 18 mm ball and coral
implant.(See figure 4) They all have pros and cons, for example the coral implant is porous and allows
tarsal and vessel growth allowing it to become "part of the patient" but on the down side it is rough and
even though it is polished and sometimes wrapped it can cause irritation, infection, and possible
rejection.
pg.4
different types of implants
(Figure 4)
We find that people who are highly allergic or on blood thinners or hemophiliacs have trouble with
these implants so patient selection is key. The peg implant is good in that there is a peg in it that locks
into the prosthetic eye, this gives us the best motility but on the down side it is more prone to infection.
The acorn implant is a wire mesh implant, neither the acorn nor peg were very successful due to many
patients getting infection with them. Fred's personal favorite is the 18 mm acrylic ball, it is easier to fit,
gives good motility and is less prone to infection or rejection.
Once the implant and orbit is healed it is time to fit the prosthetic eye. First off an impression is made of
the cavity by injecting a material called alginate or gel.(See figure 5) It is a painless procedure but it does
have to remain in for 1 to 2 minutes in order to set. This gives a "negative" of the cavity, then a wax
pattern is cast from the impression and fitted further, the resulting shape is cast in acrylic. (See figure 6)
pg.5
gel injection kit
(Figure 5)
Many people refer to prosthetic eyes as "glass" eyes, but this is a misnomer as since the 1940's they
have been made out of polymetheyl methacrylate, a type of plastic that was used in early contact
lenses. This term has probably stuck because before the 1940's they were made out of blown glass
dating back to the mid 1800's.
pg. 6
stages of prosthesis
Figure 6
Once the shape is cast in acrylic the sclera and iris are hand painted using pigments, lacquers, oils, and
sometimes even fine red thread for veins. The painting is sealed with acrylic and the clear plastic cornea
is cast and cured under heat and pressure. Then the eye is polished to a flawless surface which will
provide little resistance to the lids and no recesses for flora to grow. An alternative to doing the
impression method of fitting is to use a series of stock pre-sized artificial eyes to determine the fit,
somewhat akin to trial contact lens fitting. (See figure 7) The secret to a good fit is to capture as much
muscle movement as possible by fitting the artificial eye in the center of the implant. The ocular
prosthesis functions in several ways, it helps maintain the tissues and structure of the eye socket, allows
tears to continue cleaning and lubricating (a properly fitted prosthesis will ensure that the lubricating
tear system often operates normally) and holds the lids open to create a natural looking eye.
pg.7
pre-sized trial prosthetics'
Figure 7
When we evaluate the fit of an artificial eye we look at 7 criteria:
1. Size and lid contour
2. A proper posterior fit of the prosthesis over the anterior tissues in the ocular cavity for comfort and
motility.
3. Color of the sclera
4. Position of the plane of the iris
5. Color of the iris and pupil size
6. Movement of the artificial eye (movement of the eye is determined by the type of surgery performed
by the Ophthalmologist and the accuracy of the prosthetic fitter)
7. Finally the ultimate objective is a comfortable fit with a pleasing natural appearance.(See figure 8)
pg.8
before prosthetic eye
after prosthetic eye fitting
Figure 8
Care for the prosthetic eye is quite simple, the eye does not normally need to be removed very
frequently for cleaning, usually the patient only needs to come into the office once a year for a clean
and polish on their eye. A proper fit and the natural flora of the tears typically keeps it infection free, but
it is an individual thing and some people may need more frequent removal and cleaning. Our patients
typically come to see us on a yearly or biyearly basis for a clean and polish where the prosthesis is
removed and assessed for fit and checked for cracks. The cavity is checked for signs of infection or
irritation from improper fit. Then the prosthesis is cleaned with disinfectant then polished in three
stages, first with pumice and a rough wheel at medium speed then with a medium wheel with wax and
finally with a soft wheel at high speed to give a high shine. (See Figure 9)
pg.9
Fred polishing a prosthesis
Figure 9
It is a real joy to see someone's face light up when they look in the mirror for the first time to see their
new prosthetic eye. This is a rare occasion where the science of health care meet's art. Often when I am
performing an eye test on one of Dads prosthetic patients, I have to look at the chart to determine
which is the seeing eye, he does incredible work and the patients look so natural when he is done with
them. It really gives him a sense of accomplishment to see a patient who has undergone trauma or
disease leave our office with their head held high and improved self-image and confidence to return to
independent, productive living.
Respectfully submitted,
Fred Miller R.O.
Rick Miller R.O.,R.C.L.P.,O.A.