Diabetes Mellitus Associated Progressive Neurovascular Retinal Injury

Abstract

Diabetes mellitus is now recognized as a systemic, autoimmune, microvascular disorder, which, in the retina results in severe, multifocal injury now recognized as a leading cause, world-wide, of progressive vision loss. To address this problem in the prediabetic and overt diabetic states, it must be realized that, although the injury processes may be system wide, there are varying responses, effector, and repair mechanisms that differ from organ to organ or within varying cell structures. Specifically, within the “neurovascular unit” of the retina, lesions occur of focal microvascular occlusions, inflammatory endothelial and pericyte injury, and small vessel leakage resulting in injury to astrocytes, Müller cells, microglia, and causing progressive neuronal apoptosis and death. Such lesions are now recognized to occur before the first microaneurysms are visible by fundus camera imaging or before detectable symptoms or signs recognizable to the patient or clinician. Treatments, therefore, which currently are not initiated until edema develops or progressive vascular occlusion, are applied relatively late with some reduction in progressive cellular injury but with minimal vision improvement. Desperately needed are newly developed imaging and functional testing methods that detect the early stages of microvascular injury and neuronal apoptosis when the processes are potentially reversible, not following severe, widespread atrophy. Treatment, when applied at such early stages, therefore can preserve far better functional vision. However, to be acceptable, such interventions must be minimally invasive with patient appreciated improvement in vision. Micropulsed applications of laser retinal phototherapy appear to offer treatment for such early intervention, not just to reverse the early alterations, but also for later stages of the progressive neurovascular and vision degradation when patients will continue to present.