# "add2spec" Function. Compute the addition from IOL to spectacle plane

Computes the effective addition from the Intraocular Lens (IOL) plane to the spectacle plane by the Holladay's equation.

The addition of a Multifocal Intraocular Lens usually is given by the manufacturer at the IOL plane. However, the effective addition of the lens can vary among patients depending on some variables such as corneal power, effective lens position and IOL power. The main purpose of this function is to compute the effective addition of a MIOL considering these variables by means of the Holladay's equation.

Matlab Toolbox “refractiveAnalysis” developed by Manuel Rodríguez-Vallejo for research purposes included in the version 1.0.0 the "add2spec" function.

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

```
% DESCRIPTION
%
% Computes the effective addition from the IOL plane to the spectacle
% plane by the Holladay's equation.
% "Holladay JT. Refractive power calculations for intraocular
% lenses in the phakic eye. Am J Ophthalmol. 1993;116:63-6"
%
% PARAMETERS
%
% Kmean Mean corneal power (D)
% ELP Effective lens position from anterior corneal surface to
% anterior IOL surface (mm)
% IOL Power of the implanted intraocular lens (D)
% IOLadd Addition at the intraocular lens plane (D)
% vd Distance from the cornea to the spectacle plane (mm)
%
%
% OUTPUTS
%
% Add Addition at the spectacle plane (D)
% dist Near distance for which the addition is effective (cm)
%
% EXAMPLE
%
% [Add,dist]=add2spec(Kmean,ELP,IOL,IOLadd,vd)
%
% VERSION 1.0.0
```

References

- Holladay JT. Refractive power calculations for intraocular lenses in the phakic eye. Am J Ophthalmol. 1993;116:63-6.
- Savini G, Hoffer KJ, Lombardo M, et al (2016) Influence of the effective lens position, as predicted by axial length and keratometry, on the near add power of multifocal intraocular lenses. J Cataract Refract Surg 42:44–49.
- Eom Y, Song JS, Kim HM (2016) Spectacle plane add power of multifocal intraocular lenses according to effective lens position. Can J Ophthalmol / J Can d’Ophtalmologie 1–7.
- McKee HD, Jhanji V (2016) Theoretical Effect of Lens Position and Corneal Curvature on the Near Focal Point of Multifocal Intraocular Lenses. J Refract Surg 32:64–66.