How does The Glass Menagerie symbolize Laura's escape from reality?

The glass menagerie symbolizes the various facets of Laura's personality in many respects. For one thing, her collection of glass animals is very fragile and delicate, just like Laura herself. It also constitutes a world of its own, a miniature kingdom where everything is impeccably neat, orderly, and in its proper place. Laura feels safe in this world, far away from the disordered harshness of everyday life, where everything seems so scary, and where she always feels so terribly shy and insecure.
The little glass creatures belong to Laura; she gets to control them in a way that she could never hope to control herself, let alone the people and events in her life. The fantasy world that Laura has built for herself reflects Tennessee Williams's entire aesthetic approach in constructing The Glass Menagerie. In writing the play, Williams wanted to show that the product of the subjective imagination was more real than the minute objective detail presented to us by dramatic realism.
Yet this world of the imagination, though more real, is by the same token more prone to destruction. Laura's glass menagerie, like herself, and indeed like art in general, is achingly vulnerable to a sudden unwelcome intrusion from the world of the everyday. Laura is simply too precious for this harsh and cruel world. And although her glass menagerie allows her a momentary escape from this world, it can only ever provide temporary respite.
For Tennessee Williams, much the same could be said about art. However much heightened reality art can give us, however much of an elevated insight into the human condition it can provide, we still have to live our daily lives in the midst of a world that can all too often be so terribly cruel and unpleasant. At various times in our lives, Laura's world is our world too.