When treating patients with sickling disorders, hematologists and oncologists should know those eye lesions that require referral to an ophthalmologist, those that should lead to referral, and those that rarely are associated with decreased vision. Hyphema in any patient whose red cells contain hemoglobin S falls into the first category. Retinal neovascularization (proliferative retinopathy) and its consequence vitreous hemorrhage fall into the second. The comma sign, angioid streaks, and abnormal color vision fall into the third category. The roles of preoperative transfusion and experimental antisickling therapy in treatment and prevention of eve lesions are incompletely defined at present.