My question is can your eyesight really improve or will it always stay the same?

Cherish it!: The prescription of the eye usually stabilize around 18-22. Then around 45-50 difficulty with reading starts and maxes out by 60. During this time there a whole host of issues that can deteriorate ones vision such as cataract, glaucoma, diabetes, macular degeneration just to name some. Don't take it for granted and have your eyes examined by a competent eye doctor at least once a year!