A simple, low-cost, portable instrument for measurement of the autofluorescence of the human cornea is presented. Corneal autofluorescence has proved to be strongly correlated with the grade of retinopathy in diabetic patients. It is therefore a reliable parameter for detection of different levels of diabetic retinopathy, thus permitting timely intervention by ophthalmologists. The instrument contains custom optics and electronics and exhibits excellent linearity and repeatability both in vitro and in vivo. Preliminary tests on volunteers show promise for its use in clinical practice.