# "muPentacam" Function. Correcting Pentacam chord-mu for conventional notation

This function corrects the Kappa or chord-mu obtained from Pentacam in order to move the center of coordinates to the pupil center instead of the vertex normal. Furthermore, it corrects the differences of sign from right and left eyes in order to combine both eyes in the same plot.

It is important to note that Pentacam does not represent the mu-chord in conventional notation. It is known that Kappa angle is positive when the vertex normal is Nasal to the pupil center and negative when vertex normal is Temporal to the pupil. This convention of signs is not followed for the Pentacam reporting of chord-mu, therefore, it is required a conversion to the conventional sign notation. Furthermore, the signs change from left and right eyes. Therefore, it is required to correct the signs before combining right and left eyes in the same sample.

Matlab Toolbox “refractiveAnalysis” developed by Manuel Rodríguez-Vallejo for research purposes included in the version 1.0.0 the "muPentacam" function.

Below you have the help of the function. For more information about "refractiveAnalysis" Toolbox please Contact the author

```
% DESCRIPTION
%
% Positive angle Kappa is defined as the vertex normal Nasal to the pupil
% center.
% Negative angle Kappa is defined as the vertex normal Temporal to the pupil
% center.
%
% PENTACAM NOTATION
%
% Pentacam considers the vertex normal as center of coordinates instead
% of the pupil center.
% X component of Pentacam for Vertex Normal decentration versus the pupil
% center returns Negative Values for right eyes and Positive Values for
% left eyes when the Vertex is Nasal to the Pupil. Therefore for mixing
% results from left and right eyes there is required a conversion. The
% conversion includes a change in the coordinates system in order to make
% the pupil center as the center of coordinates.
%
% PARAMETERS
%
% V Matrix of three columns.
% First column the eye (0) for the right eye and 1 for the left eye.
% Second column the values exported from Pentacam that indicates the vertex normal from the
% pupil in horizontal (X component)
% Third column the values exported from Pentacam that indicates the vertex normal from the
% pupil in vertical (Y component)
%
% OUTPUTS
%
% K Contains [corrected values for X, corrected values for Y]
% P Contains [corrected values in polar, orientation of the vertex normal]
%
% RELATED FUNCTIONS
%
% locationPlot
%
% EXAMPLE
%
% [K,P]=kPentacam(V)
%
% VERSION 1.0.0
```