A reflectance optical perfusion sensor may include at least one light source and a plurality of detector elements arranged in a planar or nonplanar configuration, such as a three-dimensional array. The detector elements may sense light emitted by the at least one light source and reflected by a blood mass of a patient, such as blood within a blood vessel. In some examples, the detector elements may be arranged such that photodetection surfaces of at least two of the detector elements are nonparallel. In addition to or instead of the nonplanar arrangement of detector elements, an optical perfusion sensor may include a detector array including a plurality of detector elements at least partially surrounding a light source. Varying the location and orientations of detector elements may help increase a quantity of light emitted by the at least one light source and reflected toward the optical perfusion sensor by blood.
