The present model provides a reasonable match with the average values of refractive errors and aberrations (astigmatism, coma, SA, and chromatic aberrations) by fine tuning only four parameters. Several simplifying assumptions helped to keep the model complexity within reasonable limits, but as a result it is unable to predict the magnitude of other HOAs present in real eyes (mainly tetrafoil, secondary astigmatism, and sixth-order SA). In this sense the present model should be understood not as a sort of finished product but rather as advancement in the optical modeling of the eye. I tried to justify most of the assumptions, choices, and solutions adopted here, but alternative choices might be possible in most cases. Furthermore, different eye models could provide equivalent predictions of optical performance (Navarro et al.,
2006a). As explained before, both the mathematical models and the biometrical parameters of cornea and lens were chosen attending to certain criteria. Data from different studies were not mixed to compute new averages, and hence the value adopted for each parameter corresponded to only one study. That study was chosen among those best adapted to the goals of the present work (adaptation to the mathematical models, ranges of ages, accommodation, and so on) Nevertheless, rather than being based on data from a single population, this model is a combination of independent submodels (cornea, lens, and so on) that are each based on different cohorts. The basic optical models of the cornea (Navarro et al.,
2006b,
2013) and lens (Navarro et al.,
2007) were developed previously, and the most relevant aspects of those models have already been discussed. In the case of the cornea, Scheimpflug imaging permits complete and precise measurements, and hence models can attain a high fidelity and realism. The in vivo measurement of the lens is much more difficult. The changes of the aging lens geometry with accommodation were studied in vitro (Glasser & Campbell,
1998) and in vivo. In the last case, Scheimpflug imaging (Koretz, Cook, & Kaufman,
2002) provided the experimental data used here (Dubbelman et al.,
2005). More recently, powerful techniques such as optical coherence tomography (Ortiz et al.,
2012) or MRI (Kasthurirangan, Markwell, Atchison, & Pope,
2011) were also applied to study the lens in vivo. MRI results seem consistent with the data of Dubbelman et al. (
2005) used here. Regarding optical performance, there is a good agreement among different studies on both the average and standard deviations of the Zernike aberration modes in the human eye as well as their changes with pupil size, age, or accommodation.