The frame is a very important part of your spectacles, not just because it holds your lenses. The optical centre of the lens needs to be aligned with your pupil, to ensure optimal visual performance. This is even more important in multifocal lenses and lenses that correct astigmatism. If your frame is sitting skew, too high or too low, you’re no longer looking through the optical centre, which may result in poor vision or discomfort.