Of 201 patients whose presenting symptoms were acute entoptic phenomena or photopsia, or both, 150 patients had posterior vitreous detachment; 69 patients (46%) had retinal breaks; 18 (12%) had a vitreous hemorrhage without detectable retinal breaks; and two (1.3%) had peripheral retinal hemorrhages without retinal breaks or vitreous hemorrhage. Retinal breaks that occur in eyes in conjunction with acute posterior vitreous detachment are potentially dangerous and there is a possibility of delayed break formation.