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D. Nankivil, N. Ziebarth, D. Borja, E. Arrieta-Quintero, A. Ho, F. Manns, J.-M. Parel; Effect of Anterior Zonular Dissection on the Change in Lens Diameter and Power During Simulated Accommodation. Invest. Ophthalmol. Vis. Sci. 2007;48(13):5631.
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© ARVO (1962-2015); The Authors (2016-present)
To quantify the role of anterior zonular tension on the optomechanical lens response during simulation of accommodation in a lens stretcher.
Post-mortem cynomolgus monkey eyes (n=5; age: 3.75-11 years) were dissected leaving intact the lens, zonules, ciliary body, hyaloid membrane, anterior vitreous and a scleral rim. The lens was mounted in an optomechanical lens stretching system (EVAS, Parel et al, ARVO 2002) and stretched 2mm radially in a step-wise fashion. The load, lens and inner ciliary body diameters, and the lens power were measured at each step and the diameter-load and power-load relationships were quantified. The anterior zonular fibers were then carefully dissected using a diamond blade and the experiment was repeated. The changes in inner ciliary body diameter, equatorial lens diameter, and lens optical power before and after dissection of the zonules were compared.
Stretching increased the lens diameter by 0.36±0.11mm before zonular dissection and 0.47±0.18mm after zonular dissection; the inner ciliary body by 0.52±0.13mm before zonular dissection and 0.88±0.32mm after zonular dissection. The lens power decreased during stretching by 17.4±2.5D before zonular dissection and 12.6±2.0D after zonular dissection.
The lens retains a significant fraction of its accommodative ability after dissection of the anterior zonular fibers. These findings suggest that the posterior zonules, hyaloid membrane and/or anterior vitreous, play a significant role in accommodation.
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