The Elastic Tissue of Bruch's Membrane

Ultrastructural observations on the elastic lamina of Bruch's membrane of the rabbit and human eyes revealed connections to the ciliary epithelium and choroidal elastic tissue. The connections to the ciliary epithelium are in the form of bundles of microfibrils that peel off the anterior extension of Bruch's membrane beyond the ora serrata and insert into the basement membrane of the pigmented epithelium of the pars plana. The connections to the choroidal elastic tissue are in the form of bundles of microfibrils (in the rabbit) or elastin and microfibrils (in the human) that cross the tissue space between the choriocapillaris and join bundles of choroidal elastic tissue. These connections suggest that the elasticity of Bruch's membrane exerts its influence distant from the membrane itself. The connections onto the pars plana of the ciliary body implicate Bruch's membrane in disaccommodation when the ciliary muscle relaxes.