A manual instrument intended to be used to indent or imprint the surface of the sclera during an ophthalmic surgical or perioperative procedure. It is typically a hand-held instrument or a thimble-like device (placed on the end of a finger) and is made of metal (e.g., high-grade stainless steel) or synthetic polymer materials. Various types are available, including the Gass scleral marker that creates a minuscule indentation, the Awh scleral marker that creates parallel scored lines, and the Awh horseshoe design. The device is typically used for retinal detachment surgery. This is a single-use device.