*Childhood brain Cancer, InSight in Sight; New EXpertise on Tailored ophthalmological follow up in a prospective nationwide study in the Netherlands*

In the Netherlands, about 140 children per year are diagnosed with a brain
tumor. Due to improvements in diagnostics and treatment options of childhood
brain tumors, the 5-year survival rate is about 80% in developed countries. As
survival rates have increased in recent years, it is important to better
understand the long-term effects of a brain tumor and its treatment. Visual
impairment is one of these effects and can be caused by compression of the
tumor on brain tissue/nerves or obstruction of cerebrospinal fluid. However,
visual impairment can also occur as a complication of various treatments, such
as neurosurgery, radiotherapy or chemotherapy. Vision loss can affect a child's
development and can markedly affect quality of life.

The previous CCISS study has shown that visual impairment is present in 79% of
children with a brain tumor at diagnosis. However, it is not known how vision
continues to develop during and after brain tumor treatment. In addition,
ophthalmologic examinations are performed differently in each center and many
ophthalmic tests are available, making outcomes difficult to compare.

Previous research has shown that optical coherence tomography (OCT) may be of
additional value for early detection of optic nerve damage in children with a
brain tumor. However, it is not known whether OCT at diagnosis can be
predictive of long-term visual outcome. In addition, little is known about the
course of OCT parameters in children treated for a brain tumor.

1. Primary objective:
The primary aim of this study is to investigate the predictive value of OCT
parameters at diagnosis for long-term (4-5 years after diagnosis) visual
impairment (visual acuity, visual field) in children with a primary brain tumor.

2. Second objective:
The secondary aim of this study is to describe the longitudinal change of OCT
parameters (RNFL, GCL-IPL) in children with a brain tumor.

3. Third objective:
The third aim of this study is to enlarge insight in long-term (4-5 years after
diagnosis) development of visual impairment in children with different types of
brain tumors, location of the tumor, age and given treatment modalities, to
provide patient-centered information and personalized ophthalmological follow
up for children with a brain tumor.

4. Fourth objective:
To evaluate long-term (4-5 years after diagnosis) health-related and
vision-related quality of life and the relation to visual (visual field
testing, visual acuity and OCT), medical (type of brain tumor and treatment)
and sociodemographic (age, sex) variables.

The CCISS Next study is a subsequent study on the nationwide, prospective,
observational cohort CCISS study in the Netherlands. This multicenter study is
embedded in the University Medical Center Utrecht (UMCU) in association with
the Princess Máxima Center for pediatric oncology. The care and follow-up of
children with a brain tumor is centered at the Princess Máxima Center in the
Netherlands, providing a complete overview of a complete cohort of children
with brain tumors.

The following centers in the Netherlands will participate in the CCISS Next
study:
- University Medical Center Utrecht;
- Princess Máxima Center for Pediatric Oncology Utrecht.

Study design:
Nationwide prospective observational study. The study includes one cohort with
a longitudinal design.

Study setting:
Outpatient

Duration of study:
The duration of this study is 36 months. All included patients will be followed
for a period of 48 to 60 months (+/- 6 months) after inclusion in the previous
CCISS study.

Children with a brain tumor have a considerable risk of irreversible impaired
vision due to high intracranial pressure, tumor tissue pressing on the optic
pathway and eye movement disorders, either at diagnosis or during the course of
their treatment and follow up. It is reported that the harmful influence of the
tumor or its treatment on visual functioning, have a great impact on the
general psychomotor development, school participation, further educational or
social achievements and participation later in life. Moreover, visual loss due
to a brain tumor is often irreversible. Visual dysfunction should be detected
as early as possible, preferably before it has resulted in persistent and
irreversible visual loss.
Studies have shown that early detection of visual loss in some cases can lead
to improvement in visual outcomes.

Currently, the selection of the most accurate testing methods for detecting
visual decline per age and type of brain tumor are still inconsistent. An
optimization of testing methods is necessary if we want to detect early changes
in visual function and preserve visual function. Preliminary results have shown
that OCT, in addition to other ophthalmological tests (VA or VF testing) can
serve as an objective and consistent method for monitoring visual decline.
However, there are no studies available describing the predictive value of OCT
at diagnosis on long-term visual outcome when children have been treated for a
brain tumor.

The information obtained by this study and the additional investigation
(OCT-scan) will enable us to gather information about the longitudinal changes
of OCT in children with a brain tumor. Furthermore, this study will provide
information about the relation between the course of visual decline, disease
status and type of treatment in children with a brain tumor.

This study is designed to follow up the unique cohort of children with a brain
tumor included in the first CCISS study. Brain tumors are mostly found in
children. Furthermore, various aspects of the visual system are not yet fully
developed in young children. For example, normal VA improves with age, most
dramatically in the first 24 months of life, followed by a consistent phase of
slower improvement continuing up to 72 months and likely beyond. Therefore it
is important to analyze the results obtained from this study from different age
groups.

The risk of the additional investigation are negligible and the patient burden
appears minimal. Making a handheld/tabletop OCT scan is a non-invasive
procedure, which takes approximately 5-10 minutes to perform. Prior to the
handheld OCT, mydriatic eye drops will be administered for pupil dilatation.
The use of mydriatic eye drops in children is considered to be safe. Mydriatic
eye drops used in this study are also administered during regular
ophthalmologic follow up of children.
Visual acuity and visual field examinations are performed at regular ophthalmic
follow up times of children with brain tumors. For the children who no longer
undergo ophthalmic follow up, this CCISS Next study means that they will
undergo an additional one-time ophthalmic check-up.
All of the examinations conducted within the CCISS Next study were also
performed previously within the CCISS study.