It is sometimes stated (Kanski 2007, Vishwanath et al. 2008) that a posterior polar cataract has a greater effect on making vision poorer than opacities elsewhere in the crystalline lens because it is situated at the nodal point of the eye. Brown & Bron (1996) suggest that the cause is that the opacities are along the eye’s axis, rather than the relationship with the nodal point. 

Although a posterior polar or central subcapsular cataract is indeed positioned very close to the eye’s nodal point, this article demonstrates that it is the position within the eye, not the relationship to the nodal point, that is the important one.