Optometry: Open Access
Open Access

Abstract

Aim: Since the internal structural changes that occur during the lens accommodation process are not fully understood, in this study we aimed to analyze lens fibre widths during simulated accommodation. Methods: Porcine eyes (n=11) were dissected and attached to a lens stretcher. 3D image stacks (between 120 μm to 240/270 μm depth) of the anterior and posterior surfaces of five lenses, while immersed in artificial aqueous humour solution, were acquired using confocal microscopy in the un-stretched configuration and then the stretched configuration. Three lenses remained in the un-stretched configuration and three lenses were subjected to stretching. All six lenses were fixed with 4% paraformaldehyde, snap frozen and then serially cut into cryosections of 25 μm in thickness. 1 mm interval sections were incubated in PBS- wheat germ agglutinin-Hoechst 33342 solution. Lens fibre widths were measured following acquisition of fluorescent images of each lens at different depths. Result: From the confocal images, there was a significant difference between unstretched and stretched configurations in both anterior (mean lens fibre width: 5.1±0.589 μm versus 5.625±0.345 μm, p<0.0001) and posterior surfaces (5.55±0.16 μm versus 5.67±0.25 μm, p<0.0001). In fluorescent images, lens fibre widths were unchanged between unstretched and stretched configurations at depths of 1 mm (mean lens fibre width: 5.7±0.29 μm, versus 5.7±0.52 μm, p=0.411), and at 5 mm (7.7±1.89 μm, versus 7.9±2.14 μm, p=0.2309 and at 6 mm (6±1.08 μm, versus 5.97±0.89 μm, p=0.814). An increase in mean lens fibre widths was observed in stretched lenses at depths 2 mm (mean lens fibre width: 6.9±1.76 μm, versus 7.9±1.9 μm, p<0.0001), and at 3 mm (8.9±2.42 μm, versus 8.98±2.326 μm, p=0.0002), lastly at 4 mm (8.45±2.8 μm versus 9.1±2.2 μm, p=0.033). A decrease in cortical lens fibre widths occurred (mean lens fibre width: 6.67±1.37 μm versus 5.65±0.29 μm, p<0.0001) at 7 mm. Conclusion: Controversy exists as to whether nuclear lens fibres are altered during accommodation. This study shows that lens fibre width alters at some depths, but not in others during accommodation.

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