Bioengineering Studies of Transport Across Bruch's Membrane

Bruch’s membrane is a thin connective tissue layer that lies between the eye’s choriocapillaris (minute blood vessels of the choroid layer) and the retinal pigment epithelium. Since the transport of nutrients to the retina and the disposal of waste products must pass through Bruch’s membrane, the obstruction of transport through this tissue can have serious physiological consequences. It is known that the early stages of age-related macular degeneration (AMD) are characterized by minor to moderate vision loss that is associated with debris accumulation, particularly the accumulation of lipids. Dr. Johnson and his colleagues are exploring the hypothesis that this accumulation of debris impairs the transport capacity of Bruch’s membrane, leading to a progressive worsening of the condition. Because the only known risk factor for the early stages of macular degeneration is advanced age, it is important to understand how age-related changes in Bruch’s membrane may predispose some individuals to lesion development. Dr. Johnson is using a bioengineering technique called quick freeze/deep etch to examine how the transport capacity of Bruch’s membrane changes with age. The results of this study are expected to provide a firm quantitative basis for understanding the transport properties in Bruch’s membrane of eyes that have macular degeneration, leading to the development of better treatments or even a means of preventing AMD. This project is a continuation of a Macular Degeneration Research study initiated in 2001.