wasted means the person is either drunk or extremely intoxicated with drugs.
cataract is an eye condition where the person gradually loses his eyesight.There is some cloudying over on the surface of the eye ( the eye's "lens) and without treatment the person goes blind.
As for pot,there has been some research into the medicinal
properties of marijuna and supposedely it can reduce the incidents
He is making a direct reference ( jokingly) to her full-blown addiction, I think.