A polishing disk for a tool for the fine machining of optically active surfaces on spectacle lenses in particular is disclosed, which comprises a support body, to which a foam layer is attached, wherein a polishing film bears against the foam layer. The polishing film is provided with at least one opening in a central region. During machining, the opening ensures pressure equalization and makes liquid polishing agent available from inside the foam layer, as a result of which better rinsing and cooling of otherwise disadvantaged regions of the polishing disk is achieved. As a result, a polishing disk of simple and cost-effective design is proposed, which is much more durable than the prior art while achieving high surface qualities.