Personalized 3D ocular prosthesis vs Conventional prosthesis

Retinoblastoma is one of the most common eye tumors in childhood. Most children
are very young during diagnosis (<5 years). In the Netherlands annually 10-12
children get diagnosed with retinoblastoma. It can occur at both eyes or at one
eye. The visual acuity can be decreased with large tumors or tumors with a
position in the macula. Survival prognosis is good with timely diagnosis and
treatment, 90% of patient lives 5 years after diagnosis. Treatment consists of
one of the following options; Removal of the affected eye (enucleation), local
therapy (laser- or cryotherapy) chemotherapy (local or systemic) or
radiotherapy (local or external). The eye will be removed in case the eye is
filled with tumor, no vision is possible and/or chance of metastasis. After
enucleation an orbital implant is placed that fills the volume loss, and
subsequently a prosthesis is made by the ocularist.(1).

Their remaining life these children will become dependent on a prosthesis. Our
earlier studies showed that retinoblastoma patients can experience a decreased
quality of life because of bullying for their deviant appearance with the
artificial eye.(2). In another study of our group(3) it was shown that in 56.7%
of patients an improvement of appearance can be obtained with adaption of the
prosthesis, and possible surgical correction. As children grow, frequent
adaption of the prosthesis is needed for an optimal result. In the first year
after the eye removing operation frequent renewal is needed for every patient
because of the volume decrease in the first year after operation. But also
after the first year alterations of the socket occur meaning that also in
adulthood the prosthesis need frequent renewal. Our experience learns that
small alteration can have a big influence on the patients wellbeing and
satisfaction if the alteration result in a more natural looking eye. (4-7).
The production of an ocular prosthesis is a manual process with trial and error
till the correct fit is found. This process requests much patience, especially
with children what can be a tough situation. The results can then be
disappointing(8). For everyone and especially with children it is beneficial if
the process of making a fitting prosthesis is quicker and more target based.
Beside the model, the colours and textures are an important aspect for a
natural looking prosthesis. The natural eye reflects light on a different ways
with different environmental lights. Thise is due to the 3 dimensional aspect
of the iris with its crypts and folds where the colour pigments are divided on
different layers of the iris. The colour of an iris is conventionally made on a
2 dimensional surface with paint and the pupil is made by a black spot in the
centre of the iris
In our experience with microphthalmia children we experienced that 3
dimensional planning can be an important tool in developing prostheses for
children born without or with a too small eye. In these situations we have the
advantage that a MRI scan is made where the imprint of the eye socket is
scanned. With these images the ocularist can design a first prosthesis taking
the maximum values of the orbital dimensions and total surface of the
prosthesis into account. Using analysis we calculated the needed size-upscale
for subsequent prostheses in the treatment of these patients. A downside is
that it is only possible to print these 3 dimensional designed prostheses in
one colour. In this group we accept it because the primary objective is to
obtain a sufficient growth of the eye socket.

The aim of this study is to compare the 3D designed prosthesis with the
conventional made prosthesis.

Study questions:

- How is the 3D designed prosthesis compared to the conventional prosthesis?
The final chosen workflow and settings will be applied to retinoblastoma
patients who are in need of a new prosthesis. They will both receive a
conventional made model and a new 3D designed model and be asked to use both
for several weeks. The hypothesis is that the 3D produced eye is not inferior
to a conventional created prosthesis (cosmetics and comfort) and is faster in
production with lower burden to the patient. Subjective patient satisfaction
the main outcome measurement. We will also do objective measurements to compare
symmetry between artificial eye and the fellow normal eye, for both the 3D
designed eye and the conventional artificial eye. The motility will be compared
using eyetracker-based motility measurements.

Single group crossover intervention study

Participants will receive an impression of the eye socket (which is already
being done in complicated eye socket cases). Additionally, participants will be
provided with a photo of the healthy eye to replicate its colors and structures
(this is also already done in regular practice). Afterward, participants will
return to test the 3D designed prosthesis. We will perform a 3D measurement and
eye movement analysis using an eyetracker for both the 3D designed prosthesis
and the conventional prosthesis. (Both examinations have already been conducted
and tested on participants with eye prostheses in a previous study).

The fitting process will be no different from a standard fitting process,
including a mould of the socket, an iris picture and a fitting-trial for the
contour and comfort.
- Current normal practise is a visiting number of 2-3 visits to receive the
final prosthesis. In the trial the patients need to come 3 times.
- The extra burden during the visit consists of extra imaging with a hand-held
3D scanner (1 minute per scan, three in total), and extra motility tests with
an eye-tracker (max 30 minutes).
- 3D designed prosthesis for 3 weeks. At the end of the 3 weeks the patient is
asked to fill out a quality of life questionnaire.
- Rarely, a patient reacts to an ocular prosthesis with an allergic reaction,
notable as a red, irritated socket. Since the patient is already wearing an
acrylic prosthesis, it is not expected that there will be a difference with
respect to allergies.
- It can occur that the patient will have to wait several weeks before the
batch of 3D designed prostheses is finalized. Yet the patient will remain
wearing his/her original prosthesis.

There is no absolute risk, except that the patient is asked to wear an ocular
prosthesis for 3 weeks that in the worst case is not optimal comfortable. Yet,
with the final fitting trial we will adapt the shape to a maximal comfortable
fit. Also, the procedure is not different from the normal situation where the
patient is fitted with a new prosthesis. The benefit can be that the 3D
designed prosthesis is be better appreciated than a conventional prosthesis,
and when that is the case, the patient can keep the prosthesis. Also the data
regarding colour and geometry is saved so that a future prosthesis can be
replicated easily with or without small adaptations.