Diabetic retinopathy is diagnosed entirely by recognizing abnormalities on retinal images taken by fundoscopy. A tetrahydropyridoether can remove lipofuscin from retinal pigment epithelial cells. Havanese suffer primarily from luxating patella, liver disease, heart disease, cataracts and retinal dysplasia. Hemorrhagic smallpox can cause subconjunctival and retinal hemorrhages. Both microphthalmus and retinal dysplasia can cause blindness. It is known to lead to uveitis, glaucoma, and retinal detachment. The low frequency drop-off is due to lateral inhibition within the retinal ganglion cells. These colours roughly correspond to the sensitivities of the retinal ganglion cells. There are several functions of the retinal pigment epithelium. One of the main functions of the retinal pigment epithelium is to minimize oxidative stress. It is a capillary network that provides nutrients to the retinal pigment epithelium. Intermediate AMD is diagnosed by large drusen and/or any retinal pigment abnormalities. They can suffer from several types of retinal atrophy. A controversy exists as to the presence of progressive retinal atrophy in the breed. The Australian Cattle Dog is one of the dog breeds affected by progressive retinal atrophy.