Structure and function of the interphotoreceptor matrix surrounding retinal photoreceptor cells

- The IPM is a highly organized structure between the photoreceptors and the RPE.
- The IPM components are quite different from the typical extracellular matrix.
- The IPM is important for maintaining the photoreceptors and RPE.
- Characteristic changes in IPM components occur in retinal degenerations.
- Understanding IPM-mediated pathology may develop new therapeutic targets.

The interphotoreceptor matrix (IPM) is a highly organized structure with interconnected domains surrounding cone and rod photoreceptor cells and extends throughout the subretinal space. Based on known roles of the extracellular matrix in other tissues, the IPM is thought to have several prominent functions including serving as a receptor for growth factors, regulating retinoid transport, participating in cytoskeletal organization in surrounding cells, and regulation of oxygen and nutrient transport. In addition, a number of studies suggest that the IPM also may play a significant role in the etiology of retinal degenerative disorders. In this review, we describe the present knowledge concerning the structure and function of the IPM under physiological and pathological conditions.