In 1970, Lowe et al. found that the eyes with chronic ACG are smaller than normal eyes, and the lens is situated relatively more anteriorly in the eye when compared with the lens position in matched normal eyes. We also found that there is a significant relationship between LP and age (and thus, we included the age in the mixed effects regression model as confounder), which means the lens is closer to the cornea as age increases. This substantiates findings in previous studies. According to the iris-lens canal theory, the more anteriorly the lens is positioned, the more likely it is to result in “partial pupillary block.” The posterior chamber–anterior chamber pressure gradient is inversely proportional to the height of the iris-lens canal. When the lens is more anteriorly positioned and the height is decreased, the higher pressure gradient will cause a situation similar to pupillary block.