Biomedical Engineering Reference
In-Depth Information
Fig. 16
Reconstructed used holographic image
a
b
4
4
4
4
3,5
3
3,5
3
3,5
3
3,5
3
2,5
2,5
2,5
2,5
2
2
2
1,5
2
1,5
1
1
1,5
1,5
Vergence
Accommodation
Vergence
Accommodation
0,5
0,5
1
1
0
0
0,5
0,5
−
0,5
−
0,5
0
−
1
−
1
0
0
0,5
0,846
1
1,5
2
2,5
3
0
0,5
0,846
1
1,5
2
2,5
3
Time [s]
Time [s]
Fig. 17
Graph of accommodation and vergence measured on
left
(
a
)and
right
(
b
) eye by Ir.M.A.
device
interesting for a young patient than a static one. The moving part of an object
fixes the patient's attention onto a small area without vision movements affecting
measurement.
Image analysis of videosequences gained by Ir.M.A. system is similar to analysis
of E.M.AN. videosequences with modification in method for determining centre
of pupil and 1st PI. On the videosequences the both eyes are recorded, therefore
analysis has to be performed twice. Result of analysis of one eye accommodation
and vergence is in the Fig.
17
.
In initial part of graph (0-0.846 s) the analysing algorithm is calibrated. Change
of distance of the fixation object performs in 0.846 s. After that follows phase
of latency (about 200 ms) and Open-loop initiative phase of accomodation and
vergence (vergence is followed by the accommodation). Last phase of nervous
feedback, Close-loop, begins approximately in time 2 s. Course of the vergence-
accommodation synkinesis corresponds with theoretically setup curve presented
in Fig.
5
b.
