Pupil dilation allows an optometrist or ophthalmologist to see the retina, optic nerve, and blood vessels at the back of the eye. Eye examinations while the pupils are dilated may reveal early signs of glaucoma or cataracts, which are more common among diabetics than among the general population. Such examinations are also needed to diagnose diabetic retinopathy, a disease in which diabetes affects the circulatory system of the retina, leading to damage to the blood vessels and, in some cases, blindness. The American Diabetes Association recommends that diabetics see an eye care professional at least once a year for a dilated eye examination.

Using IPUMS NHIS, researchers can identify persons diagnosed with some of the eye diseases likely to be uncovered during a dilated eye examination. These diseases include cataracts (CATARACTEV, CATARACTYR), glaucoma (GLAUCOMAEV, GLAUCOMAYR), and diabetic retinopathy (DIARETINEV, DIARETINYR).

Other diabetes-related questions were periodically included in the survey; see DIABETICEV for a summary of these variables currently in IPUMS NHIS.