Introduction Since alkaline phosphatase was first reported in the retina by deConciliis in 1934,1 much study has gone into the chemical and histochemical demonstration of various phosphatases in the eye. Until recently most attention was directed to acid and alkaline phosphatase. In the past few years interest has shifted to certain "specific" phosphatases whose optimal activity occurs within or close to the physiological range of tissue pH and whose substrates are known to play important roles in intermediary metabolism. Various types of adenosine triphosphatase (ATPase) have been demonstrated in retina, ciliary body, iris sphincter, choroid, corneal epithelium, corneal endothelium, and lens capsule and epithelium.2 In certain of these loci the enzyme is thought to be concerned with cation transport. 5′-Nucleotidase has been detected in the choroid and retina.3 Yet there is little histochemical evidence for the localization of these enzymes in the eye. In 1957 Wachstein and