Person: Alonso Fernández, José
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First Name
José
Last Name
Alonso Fernández
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Óptica y Optometría
Department
Óptica
Area
Optica
Identifiers
6 results
Search Results
Now showing 1 - 6 of 6
Item Improved Analytical Theory of Ophthalmic Lens Design(Applied Sciences, 2021) Pascual, Eduardo; Gómez Pedrero, José Antonio; Alonso Fernández, JoséA revisited form of the classic third-order ophthalmic lens design theory that provides a more precise and meaningful use of aspheric surfaces and a generalization of the standard oblique errors is presented. The classical third-order theory follows from the application of the Coddington equations to a ray trace through the lens and the expansion of the incidence angles and the surface sagittas appearing on them up to order two of the radial coordinate. In this work we show that the approximations for surface sagittas and angles can be decoupled, and the lens oblique powers predicted by the proposed theory provides a better fit to the numerical results obtained by exact raytracing and multi-parametric optimization than the classical third-order theory does. Modern ophthalmic lens design uses numerical optimization and exact ray tracing, but the methods presented in this paper provide a deeper understanding of the problem and its limitations. This knowledge and the more general merit functions that are also presented may help guide the numerical approaches.Item Theoretical performance of progressive addition lenses with poorly measured individual parameters(Ophthalmic and Physiological Optics, 2023) Pascual, Eduardo; Gómez Pedrero, José Antonio; Alonso Fernández, JoséPurpose: The aim of this paper was to present a theoretical study of how poorly measured individual parameters affect the optical performance of progressive addition lenses (PALs). Modern progressive lenses can be prescribed based on parameters such as vertex distance, pantoscopic and wrap angles. These parameters can be measured from the lens wearer using specific devices; however, not all of them can be measured with the same precision, and the impact of measurement errors on the lens performance is still unknown. Methods: Data from 1900 patients were used to simulate the performance of four PAL designs with different degrees of complexity: perfect individual design, individual design with induced errors in the individual parameters, optimised design and conventional/basic design. For each patient and design, a quality metric was calculated to describe the optical performance of the lens. Results: The design having the best performance was the perfect individual design, followed by the individual design with induced errors, the optimised design and finally the conventional/basic design. Conclusions: Individual designs with measurement errors have better optical performance than lenses with less complexity, such as the optimised or conventional designs. This knowledge is useful for the eye care professional to make informed choices when dispensing these lenses.Item A generalization of Prentice's law for lenses with arbitrary refracting surfaces(Ophthalmic & Physiological Optics (OPO), 1998) Canabal Boutureira, Héctor Alfonso; Gómez Pedrero, José Antonio; Alonso Fernández, José; Bernabéu Martínez, EusebioA generalization of the Prentice's law is presented in this paper. The idea consists of removing some (but not all) of the approximations that comprise the paraxial approach. In that way, we obtain a new formulation that permits us to compute the prismatic power of a lens made up of arbitrary refracting surfaces, and to improve the precision obtained by Prentice's law when applied to monofocal lenses. The resulting formalism is simple and manageable and its derivation leads us to a precise definition of the local dioptric power matrix, introduced in a previous paper, as well as a better understanding of the same.Item Correlation between reading time and characteristics of eye fixations and progressive lens design(PLoS ONE, 2023) Concepción Grande, Pablo; Chamorro Gutiérrez, Eva; Cleva Millor, José Miguel; Alonso Fernández, José; Gómez Pedrero, José AntonioObjective: The purpose of this study is to evaluate reading time and characteristics of fixations at different distances when looking through different areas of progressive power lenses (PPL) with different power distributions by means of eye-tracking technology. Method: A wearable eye tracker system (Tobii-Pro Glasses 3) was used to record the pupil position of 28 PPL subjects when reading at near and distance vision while using 3 different PPL designs: a PPL optimized for distance vision (PPL-Distance), a PPL optimized for near vision (PPL-Near) and one of them balanced for a general use (PPL-Balance). Subjects were asked to read out loud a text displayed on a digital screen located at 5.25m and 0.37m when they were looking through the central and peripheral regions of each PPL. Reading time, total duration of fixations, and the number of fixations were analyzed for each reading condition and PPL. Statistical analysis was carried out using Statgraphics Centurion XVII.II Software. Results: The analysis of eye movements at distance-reading vision showed a statistically significant lower reading time (p = 0.004) and lower total duration of fixations (p = 0.01) for PPL-Distance. At near-reading vision, PPL-Near provided statistically significant lower reading time (p<0.001), lower total duration of fixations (p = 0.02), and less fixation count(p<0.001) in comparison with PPL-Balance and PPL-Distance. Conclusions: Reading time and fixations characteristics are affected by the power distribution of a PPL. A PPL design with a wider distance region provides better distance-reading performance while a PPL with a wider near area performs better at a near-reading task. The power distribution of PPLs influences the user performance at vision-based tasks. Thus, to provide the user with the best visual experience, PPL selection must consider user needs.Item Eye movements as a predictor of preference for progressive power lenses(Journal of Eye Movement Research, 2022) Concepción Grande, Pablo; González Dosal, Amelia; Cleva Millor, José Miguel; Alonso Fernández, José; Gómez Pedrero, José Antonio; Chamorro Gutiérrez, EvaAbstract The purpose of this study is to determine if there is any correlation between the characteristics of the user’s eye movements (EMs) and the preference of the user when wearing different Progressive power lenses (PPLs) distributions. An eye-tracker system with a sample rate of 120Hz and temporal resolution of 8.3ms (Tobii-X3-120) was used to register EMs of 38 PPL users when reading in a computer screen with 2 types of PPLs (PPL-soft and PPL-hard). Number of fixations, complete fixation time, fixation duration mean, saccade duration mean, saccade distance mean, and number of regressions were analyzed for 6 different regions of the computer screen. A statistically significant difference was observed between the characteristics of the user’s EMs and the user’s PPL subjective preference (p<0.05*). Subjects that preferred the PPL-hard presented significantly lower complete fixation time, lower fixation duration mean and lower number of regressions than those subjects indicating a preference for the PPL-soft. Results of this study suggest that eye-tracking systems can be used as PPL design recommendation systems according to the user EMs performance.Item Evaluation of an Eye-Tracking-Based Method for Assessing the Visual Performance with Progressive Lens Designs(Applied Sciences, 2023) Concepción Grande, Pablo; Chamorro Gutiérrez, Eva; Cleva Millor, José Miguel; Alonso Fernández, José; Gómez Pedrero, José AntonioDue to the lack of sensitivity of visual acuity (VA) measurement to quantify differences in visual performance between progressive power lenses (PPLs), in this study, we propose and evaluate an eye-tracking-based method to assess visual performance when wearing PPLs. A wearable eye-tracker system (Tobii-Pro Glasses 3) recorded the pupil position of 27 PPL users at near and distance vision during a VA test while wearing three PPL designs: a PPL for general use (PPL-Balance), a PPL optimized for near vision (PPL-Near), and a PPL optimized for distance vision (PPL-Distance). The participants were asked to recognize eye charts at both near and distance vision using centered and oblique gaze directions with each PPL design. The results showed no statistically significant differences between PPLs for VA. However, significant differences in eye-tracking parameters were observed between PPLs. Furthermore, PPL-Distance had a lower test duration, complete fixation time, and number of fixations at distance evaluation. PPL-Near has a lower test duration, complete fixation time, and number of fixations for near vision. In conclusion, the quality of vision with PPLs can be better characterized by incorporating eye movement parameters than the traditional evaluation method.