Iiglasi eziguqula umbala zinokutshintsha umbala ngokukhanya, njengombala omdaka okanye i-inki ekukhanyeni okunamandla kwangaphandle, kunye nokucaca ngaphakathi, kunokudlala indima yokukhusela emehlweni, ngakumbi ekuthinteleni ukukhanya kwe-ultraviolet kunye nokucoca ukukhanya okuluhlaza okwesibhakabhaka. uncedo olukhulu.
Kubantu abane-myopia abafuna ukunxiba izibuko zelanga ukuze baphume, iiglasi zokutshintsha umbala zingasindisa umthwalo wokutshintsha iiglasi ze-myopic kunye nezibuko zelanga, kwaye zinokusombulula ingxaki yokuba abanye abafazi akulula ukuphatha iiglasi ezininzi ngaphandle kweepokotho.