Biomedical Engineering Reference
In-Depth Information
the use normative data; however, it is useful to receive important indications about the
skills of the patients, at least in qualitative terms. An accurate choice of tests should be
made on a case by case basis by discussing with the entire team and depending on the
actual objectives.
To conclude, some fundamental considerations should be made. In patients with neu-
rological deficiencies of all kinds that are subject to an assessment of visual function,
we have to remember that their performances during the evaluation are not constant in
all postures. Often, huge changes can be observed in performance with changes in the
patient's posture, in the control of the head, and even in shifting from being seated to a
laying position.
Obviously it is necessary to be perfectly aware of the changes that may occur, both for a
proper organization of the location of use of assistive technologies and to be able to plan a
possible preparation period with a specific visual training.
10.3 The Role of Optometrists in the ATA Process
The description made in the previous paragraphs was aimed at giving a summary expla-
nation of vision and of the specific skills that help create efficient vision. This is true in
every clinical situation, but in the specific case of the ATA process it is necessary to use
a specific approach so that the work of the whole team can be enhanced. An optometrist
should always provide some basic information (Leslie 2004), however important the dis-
ability of the patient is, and he/she must do so in a way that allows other ATA team spe-
cialists to adapt their interventions.
The main question we are asked is, “Can the patient use vision to control and interact
through assistive technologies?” If the answer is affirmative we have to answer the next
question: “What are the operational limits of the patient?”For example, in our team it is
a consolidate practice to indicate not only the visual acuity of a patient, but also to what
equivalent stimulus dimension his/her visual acuity corresponds at different working
distances. Limitations to the saccadic movements will bring us to recommend the use of
systems with reduced scanning and with target positioned so as to minimize the effect of
the visual deficiency on the whole performance.
For every function listed above, precise indication can or, more appropriately must, be
given. This indication does not need to be an absolute value. For example, a patient affected
by strabismus whose deviated eye is bandaged will not be evaluated on the basis of the
residual functions of this eye because the aim is not to carry out a visual rehabilitation, but
to help the patient in the choice of the appropriate assistive technology. The team will be
told that that patient is not functionally using the deviated eye and that every reference to
the evaluated skills is to be considered only in relation to the fixating eye.
The exchange of information between the optometrist and his/her team must be con-
tinuous and bidirectional (Figure 10.19).
The team should inform the optometrist about the various working hypotheses and should
provide enough information about the visual abilities of the patient and the optometrist, who
in turn will provide them with information in the concrete framework of these hypotheses.
It is unnecessary to carry out detailed measurements of the field of vision if we already
plan to work in a system with minimal spatial extension.
 
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