The lens of the eye is responsible for focusing the image on the retina. Blurred vision is usually a temporary change, which can be corrected by wearing glasses. The lens of the eye becomes swollen when diabetes is out of control and this leads to short sightedness. As the diabetes comes under control, so the lens of the eye returns to normal. A pair of glasses fitted for a swollen lens at a time of uncontrolled diabetes will no longer be suitable when the diabetes is brought under control. If you have been newly diagnosed with diabetes and find that you have blurred vision, you should wait for a few months after things have settled down before visiting an optician for new spectacles. The blurred vision may improve on its own and new glasses may not be needed. Most of the serious eye problems caused by diabetes are due to damage to the retina (retinopathy). The retina is the ‘photographic plate’ at the back of the eye. Even minor changes in the retina take several years to develop but older people may have diabetes for years without being aware of it. In such cases the retina may already be damaged by the time diabetes is diagnosed. In very rare cases the lens of the eye may be permanently damaged (cataract) when diabetes is badly out of control.