Spatial Heterogenity of Iris Elasticity Measured by Indentation

Angle-closure glaucoma, pigment dispersion syndrome, and intraoperative floppy iris syndrome (IFIS) are all ocular disorders that involve abnormal morphologies of the iris. In angle-closure glaucoma, for example, the iris bows anteriorly and impedes the natural flow of the fluid (aqueous humor), which then increases the intraocular pressure (IOP) leading to vision loss. The iris contour is determined by a combination of external stresses arising from the flow of the aqueous humor [1] and internal stresses due to the passive and active components of the constituent tissues. We have previously shown that the iris has a mechanical asymmetry [2] and that posterior positioning of the dilator muscle within the iris contributes to the anterior bowing during dilation [3]; however, the relative contributions of the individual components of the iris are unknown.