俱舍論記 2.138

2.138

「若於是處至故不能見」者，識見家答。頗胝迦等，光明無隔，識見障色。壁等，光明有隔，於被障色眼識不生。

"Where there is […] therefore it cannot see" is the reply by the proponent of consciousness seeing. In the case of crystal and the like, where light is unobstructed, consciousness sees obstructed forms. In the case of walls and the like, where light is obstructed, visual consciousness does not arise with respect to obstructed forms.