Diabetes can cause all manner of problems in the eyes. One of the most common parts of the eye that is affected is the retina. If the blood sugars are not under good control, diabetic retinopathy can occur. For this reason, primary care physicians typically recommend being seen by an eye doctor for an annual exam in order to help assess whether the diabetes is truly under control.
Early diabetic retinopathy (nonproliferative diabetic retinopathy) usually starts with small retinal hemorrhages and white spots called cotton-wool spots. Small red spots called microaneurysms can also form, which can leak fluid. If this happens in the central part of the retina, it can affect vision and is called macular edema.
Because diabetes can affect small blood vessels, it can cause a lack of oxygenation to the retinal periphery. This makes the eye produce new blood vessels in an effort to help solve the problem. Unfortunately, the new vessels are very fragile and can break and cause large vitreous hemorrhages. They can even cause retinal detachments as they create scar tissue that pulls on the retina. Additionally, the new blood vessels can grow in the wrong places and even cause glaucoma! Once new blood vessels form, it is called proliferative diabetic retinopathy and requires treatment by a retina specialist.