Ocular Dominance is a naturally occurring phenomenon. One eye is naturally dominant while the other is non dominant. Much the same as hand dominance. This means one eye is usually going to see just a bit better, and improve a bit faster than the other. It is strongly advised to wait until the non dominant eye catches up, before introducing a new reduction. You might help this along with some moderate patching. Many opticians compensate for this by adding extra correction to the non dominant eye. If your "prescription" has this compensation, then at some point (generally after 2-3 spherical reductions) you will want to work toward equalizing. Also see diopter gap.