pulse2percept.vision.scotoma

Scotoma

Classes

Scotoma(mask[, name])

A region of the visual field where native vision is lost

class pulse2percept.vision.scotoma.Scotoma(mask, name=None)[source]

A region of the visual field where native vision is lost

A scotoma is eye-centered: it is defined in degrees of visual angle relative to the fovea, and it does not move when gaze does. Neither does an implant, which sits on the retina; the two hold their positions relative to each other while the scene moves past them.

A scotoma says only how much vision is lost where. What lost vision looks like – black, gray, blurred, filled in – is a separate question, and one for whoever composes the final image.

Added in version 0.11.0.

Parameters:

mask (callable) – mask(x, y) returning the loss at eye-centered visual-field coordinates x, y (in dva). 0 is intact native vision and 1 is complete loss; anything in between is a partial defect, which is what leaves room for a measured or graded scotoma without another API.
name (str, optional) – What to call this scotoma when it is printed.

Examples

A central geographic-atrophy scotoma 10 degrees across:

>>> from pulse2percept.vision import Scotoma
>>> from pulse2percept.units import dva
>>> scotoma = Scotoma.circle(5 * dva)
>>> float(scotoma(0, 0)), float(scotoma(9, 0))
(1.0, 0.0)

mirror(name=None)[source]

A copy reflected across the vertical meridian

Purely geometric: mirrored(x, y) == original(-x, y) in eye-centered visual-field coordinates.

Added in version 0.11.0.

Parameters:: name (str, optional) – Name for the mirrored scotoma (default: original name, marked as mirrored)
Returns:: scotoma – A new scotoma. The original is left unchanged.
Return type:: Scotoma

Examples

The fellow eye of a bilateral, meridian-symmetric loss:

>>> from pulse2percept.units import dva
>>> from pulse2percept.vision import Scotoma
>>> left_scotoma = Scotoma.circle(3 * dva, center=(6, 0) * dva)
>>> right_scotoma = left_scotoma.mirror()
>>> float(right_scotoma(-6, 0)), float(right_scotoma(6, 0))
(1.0, 0.0)

classmethod ellipse(x_radius, y_radius, center=(0, 0), name=None)[source]

An elliptical scotoma, lost inside and intact outside

Parameters:

x_radius (float or Quantity) – Semi-axes of the ellipse, in degrees of visual angle.
y_radius (float or Quantity) – Semi-axes of the ellipse, in degrees of visual angle.
center ((x, y), optional) – Where the ellipse sits relative to the fovea, in dva. Defaults to the fovea itself.
name (str, optional) – What to call this scotoma when it is printed.

classmethod circle(radius, center=(0, 0), name=None)[source]

A circular scotoma, lost inside and intact outside

Parameters:

radius (float or Quantity) – Radius of the scotoma, in degrees of visual angle.
center ((x, y), optional) – Where the circle sits relative to the fovea, in dva. Defaults to the fovea itself.
name (str, optional) – What to call this scotoma when it is printed.