Almost all primary PVPs and cracks that occasionally developed multifocally and coexisted with remnants of hyaloid vessels were wider horizontally than vertically. Because ocular movement is usually dominant horizontally, horizontal shear stress might generate cracks in horizontally layered premacular vitreous,6 in which remnants of hyaloid vessels may be related to the friability of the premacular vitreous. The vitreous and hyaloid vessels are symmetric along the anteroposterior axis during early development and become asymmetric after dominant growth of the temporoposterior region. Since the remnant, cracks, and PVPs were observed only temporally in the premacular vitreous, the asymmetric vitreous growth may contribute to the asymmetric location of these structures. Further study is needed to confirm our preliminary findings.