 The blue iguana 's eyes have a golden iris and red sclera . They have excellent vision , which allows them to detect shapes and motions at long distances . As blue iguanas have only a few rod cells , they have poor vision in low @-@ light conditions . At the same time , they have cells called " double cones " which give them sharp color vision and enable them to see ultraviolet wavelengths . This ability is useful when basking so the animal can ensure that it absorbs enough sunlight in the forms of UVA and UVB to produce vitamin D. 
