Of course, it is possible. Triggers of blurry vision cover a large range of eye conditions or eye disease, from simple eye strain to cataracts which might lead to vision loss. We all know that bad habit of eye usage might lead to refractive eye problem or make the problem worse. This is exactly why we need to visit our ophthalmologist on a regular base. Once we found our vision were still blurry with current eye wear, we probably need to get a new pair with different eyeglass lenses power since our eye condition is changed. Some other small eye conditions might cause blurry vision too, for example eye dryness or eye strain. With deficient lubrication in eyes, the vision can be blurry for the increased corneal friction. And as to eye strain, we can understand this easily. If we sit tight in front of a computer for more than a few hours without a break, we will have vision blurred, because our eyes need break and change of vision focus. As to wearing old contact lenses, I am guessing there are two possibilities for you to get the blurry vision. If your contact lenses are too old, I suggest you not to wear them to avoid poor vision and possible bacterial contamination. Or you might need your oculist to exam your eyes, and prescribe the new contact lenses to correct your vision by adjusting your eyewear lenses power.