## 5 Conclusions  
In conclusion, we propose a method that provides tools for studying and evaluating real environments from visual and nonvisual perspectives to improve lighting scenarios in accordance with current standards. These recommendations and standards describe models and methods to evaluate light's nonvisual effects providing confusing calculations and applications that will be hard-pressed to transfer to a real project. Our calculations show how the age of the people, that is reflected in the absorption of the crystalline lens, should be considered when nonvisual effects of light are evaluated. With these considerations, this paper can help designers to plan smart lighting projects in which the circadian cycle should be modified to achieve a specific effect or to avoid detriment to health. In this paper, we define the parameter MAFtrans, which is both SPD and age-dependent and which facilitates the quantification of the circadian light reaching the retina from measurements of the photopic illuminance at the corneal plane. Lighting designers can perform projects under traditional requirements based on photopic parameters such as luminaires with specific spatial distributions, illuminance levels at different planes, SPD and CCT of the lamps, or glare. Nowadays, circadian light is required to be evaluated according to the newer standards in terms of SPD, timing or dose but we have showed how age is an important parameter to be considered in these descriptions. Even for the same light, depending on the age of the occupants of an area, circadian light reaching the retina is very different and it should be considered when lighting projects are focused on personalized lighting.  
To summarize, personalized lighting solutions that promote healthy spaces and quality of life should have strong support for considering individual differences when defining optimal lighting specifications in lighting projects. The consensus-based metrics from CIE S 026/E:2018 offer an efficient method for typifying light spectra based on photoreceptor responses, and we support the application of this method. Despite this, lighting designers need an easy and replicative method to implement projects and comparisons across studies as well as back-test models, and our proposal simplifies this method when aging of the crystalline lens is taken into account for promoting specific areas inhabited by people having particular age ranges.  
Conceptualization, A.S.-C. and J.A.; methodology, A.S.-C. and J.A.; formal analysis, A.S.-C., J.A. and E.O.-H.; investigation, A.S.-C., J.A., [PERSON]-H. and [PERSON]-E.; data curation, A.S.-C., J.A., [PERSON]-H. and [PERSON]-E.; writing--original draft preparation, [PERSON]-H. and [PERSON]-E.; writing--review and editing, A.S.-C. and J.A. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the Agencia Estatal de Investigacion, Ministerio de Ciencia e Innovacion of the Spanish Government (Grant PID2019-107058 RB-I00 funded by MCIN/AEI/10.13039/501100011033), the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 956720, and Gobierno de Aragon-Departamento de Ciencia, Universidad y Sociedad del Conocimiento-No LMP39_21.  
Not applicable.  
The data sets of the current study are available from the corresponding author upon reasonable request.  
The authors declare no conflict of interest.