Retinal oxygen extraction in patients with type II diabetes

Diabetic retinopathy is a medical condition of the eye that can occur in patients with diabetes. It is the leading cause for blindness in the industrialized world and the number of patients with diabetic retinopathy is still rising. In patients with diabetic retinopathy, high blood sugar levels cause damage to the blood vessels and the ocular tissues, leading to swelling or leakage of these vessels. In severe cases, abnormal vessels can grow in the retina and cause permanent loss of vision. Although the exact reason for the disease has not yet been identified, there is evidence that insufficient supply with oxygen and reduced blood flow in the eye may play a key role in the disease process. We have recently developed a new and contact-free technique that is capable to measure the oxygen content and blood flow in the retina of the human eye. Based on these variables, oxygen extraction of the ocular tissue can be calculated. In the grant proposal presented here, we set out to investigate whether retinal oxygen extraction and blood flow is altered in patients with type 2 diabetes and diabetic retinopathy, and if so, if this is alteration is dependent on the clinical severity of the disease. For this purpose, we propose to perform a study in which oxygen content and blood flow is measured in patients with different clinical stages of diabetic retinopathy and compared to healthy subjects. This project will provide valuable knowledge about the oxygen metabolism in the retina and how this relates to ocular blood flow in patients with diabetes and healthy subjects. This will help us to better understand how and when vision-threatening complication in patients with diabetes develop. Furthermore, this new technology may in future be a predictive marker for the early identification of risk patients.

Diabetic retinopathy is a medical condition of the eye that can occur in patients with diabetes. It is the leading cause for blindness in the industrialized world and the number of patients with diabetic retinopathy is still rising. In patients with diabetic retinopathy, high blood sugar levels cause damage to the blood vessels and the ocular tissues, leading to swelling or leakage of these vessels. In severe cases, abnormal vessels can grow in the retina and cause permanent loss of vision. Although the exact reason for the disease has not yet been identified, there is evidence that insufficient supply with oxygen and reduced blood flow in the eye may play a key role in the disease process. We have recently developed a new and contact-free technique that is capable to measure the oxygen content and blood flow in the retina of the human eye. Based on these variables, oxygen extraction of the ocular tissue can be calculated. In the grant proposal presented here, we have investigated whether retinal oxygen extraction and blood flow is altered in patients with type 2 diabetes and diabetic retinopathy, and if so, if this is alteration is dependent on the clinical severity of the disease. Our results confirm the central hypothesis of the project, indicating that oxygen extraction in patients with diabetes is reduced. This is in keeping with the hypothesis that insufficient delivery of oxygen to the retina is an important factor that drives neovascularization and therefore contribute to the complications that finally lead to decline of visual acuity. Our results also show that oxygen extraction decreases with the severity of the disease. This could lead to new opportunities to an early identification of high-risk patients. In the future, we plan to apply this technique in other diseases, such as neurodegenerative disorders of the eye.