pulse2percept.implants.bvt

BVT24, BVT44

Classes

BVT24([x, y, z, rot, eye, stim, preprocess, ...])	24-channel suprachoroidal retinal prosthesis
BVT44([x, y, z, rot, eye, stim, preprocess, ...])	44-channel suprachoroidal retinal prosthesis

class pulse2percept.implants.bvt.BVT24(x=0, y=0, z=0, rot=0, eye='RE', stim=None, preprocess=False, safe_mode=False)

24-channel suprachoroidal retinal prosthesis

This class creates a 24-channel suprachoroidal retinal prosthesis [Layton2014], which was developed by the Bionic Vision Australia Consortium and commercialized by Bionic Vision Technologies (BVT). The center of the array is located at (x,y,z), given in microns, and the array is rotated counter-clockwise by rotation angle rot, given in degrees.

The array consists of:

• 33 platinum stimulating electrodes:

  • 30 electrodes with 600um diameter (Electrodes C1-20 (except C9, C17, C19) and Electrodes C21a-m),

  • 3 electrodes with 400um diameter (Electrodes C9, C17, C19)

• 2 return electrodes with 2000um diameter (Electrodes R1, R2)

Electrodes C21a-m are typically being ganged to provide an external ring for common ground. The center of the array is assumed to lie between Electrodes C7, C8, C9, and C13.

Note

Column order for electrode numbering is reversed in a left-eye implant.

Added in version 0.6.

Parameters:

• x/y/z (double) – 3D location of the center of the electrode array. The coordinate system is centered over the fovea. Positive x values move the electrode into the nasal retina. Positive y values move the electrode into the superior retina. Positive z values move the electrode away from the retina into the vitreous humor (sometimes called electrode-retina distance). z can either be a list with 35 entries or a scalar that is applied to all electrodes.

• rot (float) – Rotation angle of the array (deg). Positive values denote counter-clock-wise (CCW) rotations in the retinal coordinate system.

• eye ({'RE', 'LE'}, optional) – Eye in which array is implanted.

• preprocess (bool or callable, optional) – Either True/False to indicate whether to execute the implant’s default preprocessing method whenever a new stimulus is assigned, or a custom function (callable).

• safe_mode (bool, optional) – If safe mode is enabled, only charge-balanced stimuli are allowed.

property eye

Implanted eye

A ProsthesisSystem can be implanted either in a left eye (‘LE’) or right eye (‘RE’). Models such as AxonMapModel will treat left and right eyes differently (for example, adjusting the location of the optic disc).

Examples

Implant Argus II in a left eye:

>>> from pulse2percept.implants import ArgusII
>>> implant = ArgusII(eye='LE')

property earray

Electrode array

property stim

Stimulus

A stimulus can be created from many source types, such as scalars, NumPy arrays, and dictionaries (see Stimulus for a complete list).

A stimulus can be assigned either in the ProsthesisSystem constructor or later by assigning a value to stim.

Note

Unless when using dictionary notation, the number of stimuli must equal the number of electrodes in earray.

Examples

Send a biphasic pulse (30uA, 0.45ms phase duration) to an implant made from a single DiskElectrode:

>>> from pulse2percept.implants import DiskElectrode, ProsthesisSystem
>>> from pulse2percept.stimuli import BiphasicPulse
>>> implant = ProsthesisSystem(DiskElectrode(0, 0, 0, 100))
>>> implant.stim = BiphasicPulse(30, 0.45)

Stimulate Electrode B7 in Argus II with 13 uA:

>>> from pulse2percept.implants import ArgusII
>>> implant = ArgusII(stim={'B7': 13})

check_stim(stim)

Quality-check the stimulus

This method is executed every time a new value is assigned to stim.

If safe_mode is set to True, this function will only allow stimuli that are charge-balanced.

The user can define their own checks in implants that inherit from ProsthesisSystem.

Parameters:

stim (Stimulus source type) – A valid source type for the Stimulus object (e.g., scalar, NumPy array, pulse train).

property electrode_names

Return a list of all electrode names in the electrode array

property electrode_objects

Return a list of all electrode objects in the array

property electrodes

Return all electrode names and objects in the electrode array

Internally, electrodes are stored in an ordered dictionary. You can iterate over different electrodes in the array as follows:

for name, electrode in implant.electrodes.items():
    print(name, electrode)

You can access an individual electrode by indexing directly into the prosthesis system object, e.g. implant['A1'] or implant[0].

property n_electrodes

Number of electrodes in the array

This is equivalent to calling earray.n_electrodes.

plot(annotate=False, autoscale=True, ax=None, stim_cmap=False)

Plot

Parameters:

• annotate (bool, optional) – Whether to scale the axes view to the data

• autoscale (bool, optional) – Whether to adjust the x,y limits of the plot to fit the implant

• ax (matplotlib.axes._subplots.AxesSubplot, optional) – A Matplotlib axes object. If None, will either use the current axes (if exists) or create a new Axes object.

• stim_cmap (bool, str, or matplotlib colormap, optional) – If not false, the fill color of the plotted electrodes will vary based on maximum stimulus amplitude on each electrode. The chosen colormap will be used if provided

Returns:

ax (matplotlib.axes.Axes) – Returns the axis object of the plot

preprocess_stim(stim)

Preprocess the stimulus

This methods is executed every time a new value is assigned to stim.

No preprocessing is performed by default, but the user can define their own method in implants that inherit from return stim ProsthesisSystem.

A custom method must return a Stimulus object with the correct number of electrodes for the implant.

Parameters:

stim (Stimulus source type) – A valid source type for the Stimulus object (e.g., scalar, NumPy array, pulse train).

Returns:

stim_out (Stimulus object)

class pulse2percept.implants.bvt.BVT44(x=0, y=0, z=0, rot=0, eye='LE', stim=None, preprocess=False, safe_mode=False)

44-channel suprachoroidal retinal prosthesis

This class creates a 44-channel suprachoroidal retinal prosthesis [Petoe2021], which was developed by the Bionic Vision Australia Consortium and commercialized by Bionic Vision Technologies (BVT).

The center of the array (x,y,z) is located at the center of electrodes D4, D5, C4, and E4, and the array is rotated counter-clockwise by rotation angle rot, given in degrees.

The array consists of:

• 44 platinum stimulating electrodes with 1000um exposed diameter

• 2 return electrodes with 2000um diameter (Electrodes R1, R2)

The position of each electrode is measured from Figure 7 in [Petoe2021].

Note

Column order for electrode numbering is reversed in a left-eye implant.

Added in version 0.8.

Parameters:

• x/y/z (double) – 3D location of the center of the electrode array. The coordinate system is centered over the fovea. Positive x values move the electrode into the nasal retina. Positive y values move the electrode into the superior retina. Positive z values move the electrode away from the retina into the vitreous humor (sometimes called electrode-retina distance). z can either be a list with 35 entries or a scalar that is applied to all electrodes.

• rot (float) – Rotation angle of the array (deg). Positive values denote counter-clock-wise (CCW) rotations in the retinal coordinate system.

• eye ({'RE', 'LE'}, optional) – Eye in which array is implanted.

• preprocess (bool or callable, optional) – Either True/False to indicate whether to execute the implant’s default preprocessing method whenever a new stimulus is assigned, or a custom function (callable).

• safe_mode (bool, optional) – If safe mode is enabled, only charge-balanced stimuli are allowed.

property eye

Implanted eye

A ProsthesisSystem can be implanted either in a left eye (‘LE’) or right eye (‘RE’). Models such as AxonMapModel will treat left and right eyes differently (for example, adjusting the location of the optic disc).

Examples

Implant Argus II in a left eye:

>>> from pulse2percept.implants import ArgusII
>>> implant = ArgusII(eye='LE')

property earray

Electrode array

property stim

Stimulus

A stimulus can be created from many source types, such as scalars, NumPy arrays, and dictionaries (see Stimulus for a complete list).

A stimulus can be assigned either in the ProsthesisSystem constructor or later by assigning a value to stim.

Note

Unless when using dictionary notation, the number of stimuli must equal the number of electrodes in earray.

Examples

Send a biphasic pulse (30uA, 0.45ms phase duration) to an implant made from a single DiskElectrode:

>>> from pulse2percept.implants import DiskElectrode, ProsthesisSystem
>>> from pulse2percept.stimuli import BiphasicPulse
>>> implant = ProsthesisSystem(DiskElectrode(0, 0, 0, 100))
>>> implant.stim = BiphasicPulse(30, 0.45)

Stimulate Electrode B7 in Argus II with 13 uA:

>>> from pulse2percept.implants import ArgusII
>>> implant = ArgusII(stim={'B7': 13})

check_stim(stim)

Quality-check the stimulus

This method is executed every time a new value is assigned to stim.

If safe_mode is set to True, this function will only allow stimuli that are charge-balanced.

The user can define their own checks in implants that inherit from ProsthesisSystem.

Parameters:

stim (Stimulus source type) – A valid source type for the Stimulus object (e.g., scalar, NumPy array, pulse train).

property electrode_names

Return a list of all electrode names in the electrode array

property electrode_objects

Return a list of all electrode objects in the array

property electrodes

Return all electrode names and objects in the electrode array

Internally, electrodes are stored in an ordered dictionary. You can iterate over different electrodes in the array as follows:

for name, electrode in implant.electrodes.items():
    print(name, electrode)

You can access an individual electrode by indexing directly into the prosthesis system object, e.g. implant['A1'] or implant[0].

property n_electrodes

Number of electrodes in the array

This is equivalent to calling earray.n_electrodes.

plot(annotate=False, autoscale=True, ax=None, stim_cmap=False)

Plot

Parameters:

• annotate (bool, optional) – Whether to scale the axes view to the data

• autoscale (bool, optional) – Whether to adjust the x,y limits of the plot to fit the implant

• ax (matplotlib.axes._subplots.AxesSubplot, optional) – A Matplotlib axes object. If None, will either use the current axes (if exists) or create a new Axes object.

• stim_cmap (bool, str, or matplotlib colormap, optional) – If not false, the fill color of the plotted electrodes will vary based on maximum stimulus amplitude on each electrode. The chosen colormap will be used if provided

Returns:

ax (matplotlib.axes.Axes) – Returns the axis object of the plot

preprocess_stim(stim)

Preprocess the stimulus

This methods is executed every time a new value is assigned to stim.

No preprocessing is performed by default, but the user can define their own method in implants that inherit from return stim ProsthesisSystem.

A custom method must return a Stimulus object with the correct number of electrodes for the implant.

Parameters:

stim (Stimulus source type) – A valid source type for the Stimulus object (e.g., scalar, NumPy array, pulse train).

Returns:

stim_out (Stimulus object)