The vitreous in 16 patients (average age, 65 years) with asteroid hyalosis was studied and photographed using a preset lens (El Bayadi-Kajiura) and slitlamp. Asteroid hyalosis was bilateral in one patient (6%) and unilateral in 15 patients (94%). The gel was biomicroscopically normal in 13 patients (81%) and showed moderate liquefaction in three patients (19%). In ten (63%) of the 16 patients, there was no posterior vitreous detachment, in four patients (25%), there was partial vitreous detachment, and in two patients (12%), there was complete vitreous detachment. The preponderance of complete vitreous detachment was lower than expected for patients in this age group, probably because of a reduced preponderance of vitreous liquefaction in patients with asteroid hyalosis. A vitreous aspirate from one of these patients was studied using phase-contrast microscopy and scanning and transmission electron microscopy. Asteroid bodies were enmeshed within normal vitreous collagen fibrils and some were attended by macrophages or multinucleated epithelioid cells. Transmission electron microscopy disclosed irregular calcific material and complex lipids within the asteroid bodies. X-ray spectroscopy demonstrated calcium and phosphorus.