A method and related apparatus to treat a cataract where the cataractous lens is pierced and the resulting opening is mechanically maintained using a lens system device such as a pinhole device, expandable tubular lens, a stent or similar small diameter device, some of which are capable of supporting a secondary intraocular lens. The stacker includes a first surface to deform a rear end portion of the sheet, and a second surface which has a surface to press a front end portion of the sheet and is slanting so as to rise in the sheet discharging direction. The distance between the first and second lens units change during zooming. The wavelength is selected for the light energy to penetrate a full thickness of the tissue to form a volume of necrosed tissue through the thickness of the tissue.