Page 162 - Characterization of genetic neurodevelopmental disorders at adult age, with a focus on 22q11.2 deletion syndrome - Emma Boersma

Chapter 5
Discussion
The results of our study indicate that ocular findings are frequently present
in patients with 22q11.2DS. We report on ocular findings in the largest
cohort of 22q11.2DS patients to date.
Importantly, VA was (near) normal in almost all patients. Severe visual
impairment was reported for two children, one with Peters’ anomaly and
one with keratoconus, posterior subcapsular cataract and tapetoretinal
degeneration with a suspected second genetic hit. It is important to detect
visual impairment because of its impact on language and communication
development and for its negative effect on psychiatric illness such as
depression or anxiety.18, 19 Patients with intellectual disabilities and visual
impairment may have an atypical presentation, such as self-injurious
behavior or functional deterioration.20 Also, fatigue and headaches are
common in 22q11.2DS,21 and may be caused by visual impairment in some
cases. When measuring VA of patients with 22q11.2DS, cognitive abilities
should be taken into account.
We found a high prevalence of moderate to severe hyperopia, especially
in children with 22q11.2DS aged six years and older, compared to
children and adults in the general population and also children with
intellectual disabilities.22-24 Studies in the general population have shown
that emmetropisation takes place during early development resulting in
a reduction and stabilization of refractive errors in early teenage years,25,
26 which was not the case in our cohort. A possible reason for the high
prevalence of hyperopia may be that the axial length of the eye is too short
relative to the refractive power of the lens or cornea because of a delay in
growth. Also, lag in accommodation has been found in children with severe
hyperopia in the general population and may have contributed to the high
prevalence of moderate to severe hyperopia in our study.27 In addition, the
prevalence of astigmatism in children and adults with 22q11.2DS was
much higher compared to the general population and compared to adults
with intellectual disabilities.23, 28 Also, in our cross-sectional study, high
astigmatism was more frequently present compared to previous studies
in 22q11.2DS. This may be explained by a higher inclusion rate of adults
in our study, in whom astigmatism was found more often. Against-the-rule
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