Biology subjects

Goethals, S.

Publications and source records attributed to Goethals, S..

3 recordsLinked to original sources

bioRxiv2026

Predicting the Efficacy of Myopia Control Spectacle Lenses by Simulating Their Optical Effect on the Retina

Slowing myopia progression is central to addressing a growing public health concern. Myopia control spectacle lenses with diverse optical designs have been proposed for this purpose, and show varying degrees of clinical efficacy. Relating their design to their efficacy remains an open challenge. Here we show that it is possible to predict their clinical efficacy from their optical design, by reconstructing their impact on the retinal image. We simulated how several lens designs affect the retinal image using a combined lens and eye optical model. By assuming that the retina extracts specific features from the retinal image to modulate eye growth, we could predict the cumulative absolute reduction in axial elongation (CARE) of lens designs with very different rationales and microstructures. Our results show that different myopia control spectacle lenses can be compared on a common optical basis, and that their efficacy is predictable from their optical properties. This work paves the way for rational design of next-generation lenses and for adapting designs to each patient's ocular optics.

neuroscience↗

bioRxiv2020

Properties of the axial current of retinal ganglion cells at spike initiation

The action potential of most vertebrate neurons initiates in the axon initial segment (AIS), and is then transmitted to the soma where it is regenerated by somatodendritic sodium channels. For successful transmission, the AIS must produce a strong axial current, so as to depolarize the soma to the threshold for somatic regeneration. Theoretically, this axial current depends on AIS geometry and Na+ conductance density. We measured the axial current of mouse RGCs using whole-cell recordings with post-hoc AIS labeling. We found that this current is large, implying high Na+ conductance density, and carries a charge that co-varies with capacitance so as to depolarize the soma by ~30 mV. Additionally, we observed that the axial current attenuates strongly with depolarization, consistent with sodium channel inactivation, but temporally broadens so as to preserve the transmitted charge. Thus, the AIS appears to be organized so as to reliably backpropagate the axonal action potential.

neuroscience↗

bioRxiv2019

Theoretical relation between axon initial segment geometry and excitability

In most vertebrate neurons, action potentials are triggered at the distal end of the axon initial segment (AIS). Both position and length of the AIS vary across and within neuron types, with activity, development and pathology. What is the impact of AIS geometry on excitability? Direct empirical assessment has proven difficult because of the many potential confounding factors. Here we carried a principled theoretical analysis to answer this question. We provide a simple formula relating AIS geometry and sodium conductance density to the somatic voltage threshold. A distal shift of the AIS normally produces a (modest) increase in excitability, but we explain how this pattern can reverse if a hyperpolarizing current is present at the AIS, due to resistive coupling with the soma. This work provides a theoretical tool to assess the significance of structural AIS plasticity for electrical function.

neuroscience↗