Abstract: An instrument and method for performing a capsulotomy where the instrument is in the form of a tubular probe through which irrigation fluid may be passed, the end of the probe carrying a thin blade pivotable about an axis transverse to the axis of the tubular probe, the blade being disposed eccentrically with reference to the axis, with its major trailing cutting edge located toward the rear of the blade and at a greater distance from the axis than the leading end of the blade so that, when the leading end of the blade is applied to cut the anterior wall of the capsule, the cutting is completed by the swiveling of the blade about the axis to follow the movement of the leading end. The method involves the use of this blade to perform a circular cut in the capsule wall through which the cataract may be drawn out.