Matrix controlled diffusion drug delivery systems based on one or more silicone-containing monomers of the general formula: ##STR00001## wherein x, y, m, m', R, R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.6, R.sup.7, X, Z and Z' are as defined herein are provided, wherein the matrix controlled diffusion drug delivery systems are sized and configured for back of the eye delivery.