ili ary ▁ep ith el ium ▁and ▁pass ▁forward ▁closely ▁related ▁to ▁the ▁later al ▁surfaces ▁of ▁the ▁c ili ary ▁process ▁of ▁the ▁par s ▁p lic ata . ▁ ▁When ▁colour ▁gran ules ▁are ▁disp la ced ▁from ▁the ▁Z on ules ▁of ▁Z inn ▁( by ▁fr iction ▁against ▁the ▁l ens ), ▁the ▁ir ises ▁slowly ▁fade . ▁ ▁In ▁some ▁cases ▁those ▁colour ▁gran ules ▁c log ▁the ▁channels ▁and ▁lead ▁to ▁Gla u com a ▁P ig ment osa . ▁ ▁The ▁z on ules ▁are ▁primarily ▁made ▁of ▁f ibr ill in , ▁a ▁connect ive ▁t issue ▁protein . ▁ ▁Mut ations ▁in ▁the ▁f ibr ill in ▁gene ▁lead ▁to ▁the ▁condition ▁Mar fan ▁synd rome , ▁and ▁consequences ▁include ▁an ▁increased ▁risk ▁of ▁l ens ▁dis location . ▁ ▁C lin ical ▁appearance ▁The ▁z on ules ▁of ▁Z inn ▁are ▁difficult ▁to ▁visual ize ▁using ▁a ▁sl it ▁lamp , ▁but ▁may ▁be ▁seen ▁with ▁exception al ▁d ilation ▁of ▁the ▁pup il , ▁or ▁if ▁a ▁col ob oma ▁of ▁the ▁ir is ▁or ▁a ▁sub l ux ation ▁of ▁the ▁l ens ▁is ▁present . ▁ ▁The ▁number ▁of ▁z on ules ▁present ▁in ▁a ▁person ▁appears ▁to ▁decrease ▁with ▁age . ▁The ▁z on ules ▁insert ▁around ▁the ▁outer ▁margin ▁of ▁the ▁l ens ▁( equ ator ), ▁both ▁anterior ly ▁and ▁posterior ly . ▁ ▁Add itional ▁images ▁ ▁References ▁ ▁External ▁links ▁ ▁Di agram ▁at ▁un