Abstract
Purpose: :
Determining the mechanical properties of lenses is important for developing a suitable polymer for an artificial lens. Here we examined the importance of alphaB-crystallin in the mechanical properties, specifically the elastic modulus, of the mouse lens. This is the first time that elastic modulus of a mouse lens has been measured.
Methods: :
Eyes were extracted from newly sacrificed wild type and heterozygous alphaB-crystallin R120G mutant knock-in mice. The lenses were dissected, keeping the capsule attached. Each lens was weighed and suspended in a 3 % w/v agar gel, which was made isotonic via inclusion of minimum essential medium (MEM). The gel was carefully removed to expose half of the lens. A microindenter was then used to determine the elastic modulus of the lens. In all, 10 wild type and 20 heterozygous lenses were tested.
Results: :
An analysis of variance indicated that the elastic modulus was significantly impacted by age (p=0.003) but not genotype (p=0.526). The mean elastic modulus was found to be 3770 Pa at an age of 1 month. It increased to 4600 Pa at 2 months and 5700 Pa at 6 months (Figure 1). No significant differences in elastic modulus relative to the wild type were noted when R120G alphaB-crystallin heterozygous mouse lenses were tested.
Conclusions: :
Mouse lens age significantly increases the elastic modulus of the lens. AlphaB-crystallin R120G mutation does not appear to contribute to the mechanical properties of the lens in heterozygous mouse lenses. The decreased solubility of mutant alphaB-crystallin does not significantly affect the mechanical properties of mouse lenses. This agrees with previous work indicating that soluble lens proteins may not significantly contribute to the elastic properties of the lens.
Keywords: crystallins • mutations • presbyopia