visisipy.refraction

Utilities for handling refraction data.

Classes

FourierPowerVectorRefraction	Ocular refraction in Fourier power vector form.
PolarPowerVectorRefraction	Ocular refraction in polar power vector form.
SpheroCylindricalRefraction	Ocular refraction in sphero-cylindrical form.

Module Contents

class visisipy.refraction.FourierPowerVectorRefraction

Ocular refraction in Fourier power vector form.

This is the default representation of refractions in visisipy. This class contains several methods to convert the refraction to other forms, using the conversions defined in [1].

[1]

Thibos LN, Wheeler W, Horner D. Power vectors: an application of Fourier analysis to the description and statistical analysis of refractive error. Optometry and vision science: official publication of the American Academy of Optometry. 1997 Jun;74(6):367-75.

Attributes

Mfloat

The power of the refraction.

J0float

The Jackson cross-cylinder power at 0°.

J45float

The Jackson cross-cylinder power at 45°.

Methods

to_polar_power_vectors() -> PolarPowerVectorRefraction

Converts the refraction to polar power vector form.

to_sphero_cylindrical(cylinder_form: Literal[“positive”, “negative”] = “negative”) -> SpheroCylindricalRefraction

Converts the refraction to sphero-cylindrical form.

to_polar_power_vectors() → PolarPowerVectorRefraction

Converts the refraction to polar power vector form.

Returns

PolarPowerVectorRefraction

The refraction in polar power vector form.

to_sphero_cylindrical(cylinder_form: Literal['positive', 'negative'] = 'negative') → SpheroCylindricalRefraction

Converts the refraction to sphero-cylindrical form.

Parameters

cylinder_formstr, optional

Indicates if the cylinder should be positive or negative. Defaults to “negative”.

Returns

SpheroCylindricalRefraction

The refraction in sphero-cylindrical form.

class visisipy.refraction.PolarPowerVectorRefraction

Ocular refraction in polar power vector form.

Attributes

Mfloat

The power of the refraction.

Jfloat

The Jackson cross-cylinder power.

axisfloat

The axis of the Jackson cross-cylinder power.

class visisipy.refraction.SpheroCylindricalRefraction

Ocular refraction in sphero-cylindrical form.

Attributes

spherefloat

The spherical component of the refraction.

cylinderfloat

The cylindrical component of the refraction.

axisfloat

The axis of the cylindrical component of the refraction.

Methods

has_positive_cylinder() -> bool

Returns True if the cylinder is positive or NaN, False otherwise.

has_negative_cylinder() -> bool

Returns True if the cylinder is negative or NaN, False otherwise.

convert_cylinder_form(to: Literal[“positive”, “negative”]) -> SpheroCylindricalRefraction

Converts from positive cylinder refraction to negative cylinder refraction and vice-versa.

property has_positive_cylinder: bool

Returns True if the cylinder is positive or NaN, False otherwise.

property has_negative_cylinder: bool

Returns True if the cylinder is negative or NaN, False otherwise.

convert_cylinder_form(to: Literal['positive', 'negative']) → SpheroCylindricalRefraction

Converts from positive cylinder refraction to negative cylinder refraction and vice-versa.

Parameters

tostr

Indicates if the conversion should be done towards negative cylinder form (“negative”) or positive cylinder form (“positive”).

Returns

SpheroCylindricalRefraction, optional

With inplace set to True, no return is given as the current class is updated. With inplace set to False, a copy of the current SpheroCylindricalRefraction instance is returned, but in the specified cylinder format.

Raises

ValueError

When the parameter “to” is not set to ‘positive’ or ‘negative’.