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M. Berthold Lindstedt et al.
to asthenopic symptoms and visual fatigue (17). An-
other aspect is the reduced accuracy and automaticity
in eye movements. Clear and single vision, which is
normally maintained subconsciously, tends to be less
perseverant and more variable in patients with ABI and
to require conscious mental effort to compensate. Thus,
this may have a negative impact on mental capacity and
endurance. This is further supported by the results of
the study by Show et al. (35), showing reduced fatigue
following a rehabilitation programme including visual
rehabilitation of ocular motor dysfunctions.
Whether ocular motor disorder is a consequence of
mental fatigue or an isolated aspect that contributes to
the level of mental fatigue needs to be further elabo-
rated. However, the findings of the present study open
opportunities for further research into the role of visual
function as a component in mental fatigue.
Visual deficits and anxiety/depression
There was no significant association between increased
visual deficits and high levels of depression and anx-
iety in the present study. Univariate analysis showed
a significant association between VI score and HADS,
but this significance disappeared on adjustment with
the factors in the logistic regression model. However,
Gall et al. (36) examined 122 patients with visual field
defects after stroke. The level of distress was increased
and increased further if other sensory systems were
injured. In the study by Sand et al. (33) an association
between vision dysfunction and both depression and
anxiety was described.
The characteristics of the visual symptoms differed
between those with or without anxiety/depression, par-
ticularly regarding reading difficulties, blurred vision,
light sensitivity, light-dependent issues, and an increased
tendency to bump into objects or persons. Goodrich et
al. (21) found that the TBI-PTSD group experienced
more problems, especially regarding light sensitivity
and reading difficulties. These symptoms are among
those with the highest diversity in our study, and one
may speculate that there might be an association bet-
ween certain visual symptoms and anxiety/depression.
Limitations
Fifteen percent of the patients did not return the MFS
questionnaire and 10% did not return the HADS.
Completing and returning a questionnaire may be too
demanding for patients with cognitive and/or emo-
tional deficits, and this may conceal that there was
a selection of more active patients with less mental
fatigue, depression and anxiety.
As pointed out above, patients with different
diagnoses and a diversity of visual symptoms and
www.medicaljournals.se/jrm
dysfunctions were included in the present study. The
diagnoses differ in number. This may have influenced
the result; however, we believe that the main results
are valid for the 2 main diagnoses, i.e. TBI and stroke.
Conclusion
Finally, both visual disturbances and mental fatigue are
common after ABI. The current study found an asso-
ciation between increased number of visual symptoms
and increasing mental fatigue. Thus, visual-related
symptoms should be considered in the management
of mental fatigue. These findings warrant further ela-
boration, and it is possible that vision rehabilitation is
a tool to mitigate mental fatigue.
ACKNOWLEDGEMENTS
The authors would like to thank the team at Huddinge for help
and support. This study was founded by Stiftelsen Torsnspiran,
Strokeförbundet and the community of Stockholm.
The authors have no conflicts of interest to declare.
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