Tom accidentally breaks some of Laura's treasured glass collection as he rushes out the door. Laura screams "My glass! --Menagerie", covering her face and turning away. The shattered glass represents Laura's shattered feeling as her family is in turmoil. She turns away from broken glass because she wants to turn away from reality.
It is obvious that Laura feels at fault for the tension in the house because in scene four, she persuades Tom to apologize to Amanda and make peace. It is in this scene where Amanda tells Tom that Laura cannot spend the rest of her life playing the Victoria and fooling with the pieces of glass. The reference to the glass in this scene used by Amanda suggests Laura's wasting life.
On page 16, Amanda's fear is exposed when she ridicules Laura of how she will stay home and amuse herself with the glass menagerie and eternally play the worn-out phonograph records for the rest of her life. In scene five, Tom and his mother discuss about the gentleman caller that Tom has invited over for dinner to meet Laura. Amanda goes on about what trait the man should have and not have and Tom tries to snap Amanda into reality by telling her that she should not expect too much of her crippled daughter who lives in a world of glass ornaments. Because they love her so much, they do not realize what other people visualize Laura as--a very different girl.
In this scene Tom's reference to the glass refers to Laura's different and fragile character. She is very fragile because she gets sick at the slightest uncomfortable situation, such as being in public or when she is asked to eat dinner with the gentleman caller. In scene six, page 57, when Amanda desperately asks Laura to open the door for the gentleman caller, Laura is very hesitant and tells her mom she's sick. Amanda goes on saying she's sick too of her nonsense and asks why she can"t be a normal person. Laura ends up very sick and ends up lying down on the sofa during the dinner.