Of course you need! Once sufferring from myopia, you should go to the professional ophthalmic hospital and get prescription eyeglasses. Because even slightly nearsighted of -100, the ajusting capacity of muscles of the eyes have become imbalanced.
As you are slightly nearsighted of -100, I suggest you just wear glasses while working, watching TV, or facing the computer. In addition, take care of your eyes to avoid worse condition.