Recent methodological and technical developments in comparative morphology have broadened understanding of evolutionary traits in molluscs. Scientists are capable of reconstructing organ systems and entire architectural physiologies with utmost precision. The pallial eyes of Pectinidae are amongst the most complex visual systems found in molluscs and have aroused scientific curiosity for decades. This investigation presents the most comprehensive description of pallial eye morphology in four major groups of Pectinidae: Aequipectini group, Pectininae, Chlamydinae and Palliolinae. The cornea, lens, retinae and branching of the optic nerve are depicted in topographic detail. Three-dimensional reconstructions of microtome sections enable the comparison of whole eyes and structures in contrast to single-section analysis. Here, we demonstrate two significant findings: (i) the morphology of corneae and lenses varies in scallop species and (ii) the retinae are innervated in different ways in different species. Moreover, we show how morphological characteristics such as the hyperbolic shape of the lens can be overlooked if only single sections are investigated.