A cassette 74 for use with an ophthalmic surgical pump 16 for collecting aspirant fluid and tissue from a patient's eye includes a rigid walled container 18 having an interior volume 42. At least one tapered alignment slot 20 is formed in a side wall of the container 18 and extends from a back wall 24 towards a front wall 26. An irrigation and aspiration manifold base 50 is removeably attached to the container 18. An aspiration path 46 is formed within the container 18 for receiving the aspiration fluid and the tissue from the eye and directing the flow of fluid towards a front half of the container 18 before the fluid and tissue collects within a majority of the interior volume 42 of the container 18. A fluid level indicator 34 is formed on a wall 22 of the container 18, such that an associated photo-detector 86 of the pump 16 may determine a level of fluid in the container 18.