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V. Teuma, G. Gray, J. Bielitzki, S. Bott, R. Frey, J. Kuszak; FEA Simulation of Photodisruptive Laser Cutting Algorithms to Increase the Accommodative Amplitude in the Presbyopic Human Crystalline Lens. Invest. Ophthalmol. Vis. Sci. 2009;50(13):6132.
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© ARVO (1962-2015); The Authors (2016-present)
Finite Element Analysis (FEA) modeling using crystalline lens "spring back" properties has been developed to investigate the potential for improving the accommodative amplitude in human lenses resulting from photodisruptive laser treatment.
FEA models were constructed based on a theory of the lens "springback" capability. FEA was used to evaluate certain cutting algorithms and their effects on the relative change in optical power during simulated accommodative processes. A human lens model representative of a typical 10 year old was constructed and radially stretched under normal physiological zonular tension to calculate an initial spring back force in a lens with large amplitude of accommodation. Three lens models were then constructed using the Young’s moduli of the nucleus and the cortex in individuals 35, 45 and 55 year-old based on the Heys’ data showing increases in lens stiffness with age. These data were adjusted to provide the best simultaneous fit of the 3 different ages with targeted values of the accommodative amplitudes of 4, 1 and less than 0.5 diopters respectively using the previously calculated spring back force. The same procedure was followed on the 3 stretched models with the same combinations for Young’s modulus but in these cases a multi layer laser cutting algorithm was applied to the segments of the lens nucleus.
The results show that the laser cutting algorithm increased accommodative amplitude by more than 2 diopters with the same lens "spring back" force compared to the uncut lens for the 45 year old presbyopic lens model.
The lens "spring back" approach in FEA may provide insight into the relative effectiveness of laser cutting algorithms to restore a measure of accommodative amplitude in presbyopic lenses.
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