# Optical Behavior of an Enhanced Monofocal Intraocular Lens Compared with a Standard One
## 2 Materials and Methods
### Power Profile Mapping and Wavefront Analysis  
The device NIMO TR1504 (LAMBDA-X, Nivelles, Belgium) used in this study measures the refractive effective power and complete wavefront aberrations of monofocal, toric and multifocal IOLs. The device is based on the phase-shifting Schlieren principle [11]. By combining this principle with the phase-shifting method generally used in interferometry [12; 13; 14], the NIMO system is able to measure light beam distortions and use these to calculate the power characteristics of optical lenses; it also conducts wavefront analysis, considering up to order 13 of the Zernike coefficients. The measurement light source shows a radiance peak at 546 nm, which is close to the spectral relative luminance efficacy peak of the human visual system, located at 555 nm under photopic conditions [15].  
Once the fringes pattern has been captured, NIMO TR1504 computes data and allows for a detailed measurement of the power distribution within any selected optic zone; the instrument's software also enables wavefront analysis via Zernike polynomial decomposition at different optical aperture diameters of the lens [16]. In this study, the maximum analyzed optical zone for each IOL was set to 4.5 mm, which allowed us to provide information in a range of real-life scenarios, including pupil sizes up to this value.  
To compute the addition, the difference between the radial power measurements obtained and the nominal power provided by the manufacturer of the lens was calculated.  
The parameters measured in this study were radial power profiles expressed in diopters; the root mean square (RMS) of the total high-order aberrations (HOAs) (from the third to thirteenth order); and the coefficient of the primary \((Z^{0}_{4})\), secondary \((Z^{0}_{6})\) and high-order (\((Z^{0}_{8})\), \((Z^{0}_{10})\) and \((Z^{0}_{12})\)) spherical aberrations expressed in microns for different optical aperture diameters. The RMS was studied for 3 mm and 4.5 mm.  
The measurements were carried out following the protocol published by [PERSON] et al. [17] for IOLs. In order to prevent surface distortion and loss of moisture during the measurements, intraocular lenses were placed in a quartz cuvette without aberrations and immersed in a saline solution, as specified in the NIMO TR1504 manual. Without a lens present, the chamber maintained uniform illumination. Conversely, when a lens was introduced into the instrument's object plane, the light rays originating from the source underwent a shift or deflection. This, in turn, modulated the intensity of light reaching the pixels of the high-resolution CCD camera, creating what is commonly referred to as Schlieren fringes. The higher the power of the test lens, the more pronounced the deviation of light rays and the increased occurrence of these fringes. Employing phase-shifting techniques, a cartographic representation of both horizontal and vertical components of ray deflection was generated. The power maps corresponding to these were derived from the ray deflection map. Ten measurements were conducted for each lens in every assessed area to derive average values. These measurements were executed without any filters, treating the lens as a thin lens, thereby obviating the necessity to know the central thickness and curvature, as reported by [PERSON] et al. [17].