Diabetes Mellitus is a systemic condition that can impact almost every organ system in the human body. In addition to the well-known effects on major systems such as cardiovascular or renal, Diabetes can have profound impact on the eyes and the visual system.
Diabetes can cause rapid fluctuations in the blood sugars, which can thereby cause changes in vision. Patients often describe blurring of vision corresponding to rapid increase in the blood sugar. This is partly because the increased sugars will enter the human lens in periods of relatively high sugar. These sugars cannot leave the lens easily and water follows resulting in the swelling of the human lens. This Sorbitol pathway utilized the enzyme aldose reductase which is found in only a few placed in the human body. This type of blurred vision usually transient and returns to normal after the blood sugars have come back to their baseline levels. Over the course of time, diabetic patients can have early onset cataract formation compared to their counterparts.
Diabetes can also have slow, progressive changes in the eye because of its ischemic nature. The blood cells of diabetics are in a relatively ischemic (decreased oxygen) state when in a hyperglycemic state. This ischemic state results in poor perfusion or nourishment to the ocular tissues. This ischemia over time can result in new blood vessel formation or neovascularization. These blood vessels can eventually bleed or leak causing vision loss. In addition to causing “retinopathy” (pathology in the retina), this can also contribute to glaucoma.
It is usually recommended for most diabetic patients to obtain a comprehensive eye exam including dilated fundusopic exam every year. During this eye exam, the eye doctor can look for changes in the structures of the eye including the lens and the retina. Many patients with early changes from diabetic eye disease may not have any visual changes. However, careful tracking of the eye is necessary and can be critical in management of the disease. Eye doctors and primary care providers work as a team to make sure that diabetes is well managed.