Purpose: Micrometer-sized spherules formed of hydroxyapatite or whitlockite were identified within extracellular deposits that accumulate in the space between the basal lamina (BL) of retinal pigment epithelium (RPE) and the inner collagenous layer of Bruch's membrane (sub-RPEeBL space). This investigation aimed to characterize the morphologic features, structure, and distribution of these spherules in aged human eyes with and without clinical indications of age-related macular degeneration (AMD).Design: Experimental study.Participants: Five human eyes with varying degrees of sub-RPEeBL deposits were obtained from the University College London Institute of Ophthalmology and Moorfield's Eye Hospital Tissue Repository or the Advancing Sight Network. Two eyes were reported as having clinical indications of AMD (age, 76e87 years), whereas 3 were considered healthy (age, 69e91 years).Methods: Cadaveric eyes with sub-RPEeBL deposits were embedded in paraffin wax and sectioned to a thickness of 4-10 mm. Spherules were identified and characterized using high-resolution scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy, and time-of-flight secondary ion mass spectroscopy.Main Outcome Measures: High-resolution scanning electron micrographs of spherules, the size-frequency distribution of spherules including average diameter, and the distribution of particles across the central-peripheral axis. Elemental maps and time-of-flight secondary ion mass spectra also were obtained.Results: The precipitation of spherules is ubiquitous across the central, mid-peripheral, and far-peripheral axis in aged human eyes. No significant difference was found in the frequency of spherules along this axis. However, statistical analysis indicated that spherules exhibited significantly different sizes in these regions. Indepth analysis revealed that spherules in the sub-RPEeBL space of eyes with clinical signs of AMD were significantly larger (median diameter, 1.64 mm) than those in healthy aged eyes (median diameter, 1.16 mm).Finally, spherules showed great variation in surface topography and internal structure.Conclusions: The precipitation of spherules in the sub-RPEeBL space is ubiquitous across the centraleperipheral axis in aged human eyes. However, a marked difference exists in the size and frequency of spherules in eyes with clinical signs of AMD compared to those without, suggesting that the size and frequency of spherules may be associated with AMD.