Table 1.
Clinical characteristics of patients with amblyopia.
Figure 1.
(A) Participants fixated on a cross displayed on a computer monitor, with their index finger placed on a force sensitive resistor (FSR). The target was a high contrast circle (visual angle 0.25°) shown after a random delay (range 1.5–3 sec) at ±5° or ±10°. (B) The 3D reach vector, defined as a straight line connecting the initial and end position of the finger, was calculated from the finger trajectory data. For each trial, we also computed the angle between the reach vector and the target vector (defined as a straight path connecting the initial position of the finger and target location).
Table 2.
Kinematics of the reach vector (mean ± standard deviation).
Figure 2.
Representative reach trajectory.
Typical data showing the reach vector trajectory to the +10° target in a representative control subject (left column), patient with mild amblyopia (middle column), and severe amblyopia (right column) during binocular viewing (top row), fellow eye (right eye in control) viewing (middle row), and amblyopic eye (left eye in control) viewing (bottom row). Patients with mild and severe amblyopia had greater variability in spatial limb position during reaching in comparison to the control subject.
Table 3.
Kinematics of the reach trajectory 50 ms after movement onset (mean ± standard deviation).
Figure 3.
Reach precision during acceleration.
Patients with mild and severe amblyopia had significantly reduced precision of the vector angle at 50 ms following movement onset (A), and 100 ms after the onset of movement (B). For control subjects, fellow eye is the right eye and amblyopic eye is the left eye. Error bars = ±1 standard error.
Table 4.
Kinematics of the reach trajectory 100 ms after movement onset (mean ± standard deviation).
Figure 4.
Mean endpoint precision (variable error) of the reaching movement along the azimuth (A), elevation (B), and depth axes (C). Patients with severe amblyopia had reduced precision during amblyopic eye viewing along azimuth (p<0.0001) and elevation axes (p<0.05), and during all viewing conditions along the depth axis (p<0.01). For control subjects, fellow eye is the right eye and amblyopic eye is the left eye. Error bars = ±1 standard error.
Table 5.
Endpoint precision of the reach (mean ± standard deviation).
Figure 5.
Proportion of explained variance.
R2 values (Fisher z scores) relating the spatial location of the finger at 10% intervals (normalized to movement time) to the overall movement amplitude during binocular (left column), fellow eye (middle column) and amblyopic eye (right column) along the azimuth (top row), elevation (middle row), and depth axes (bottom row). There was no significant difference between control participants and patients with mild amblyopia in all viewing conditions in all three axes. However, patients with severe amblyopia had significantly higher R2 values at 70% of movement time along elevation (p<0.05) during amblyopic eye viewing, and along the depth axis (p<0.01) in all viewing conditions. The higher R2 values in the latter half of the trajectory indicate that movements relied heavily on pre-programmed responses.