Abstract: A caliper for ophthalmic surgery comprises a pair of arms which are relatively pivotable, with each arm terminating at one end in a tip, and with the tips being movable between closed and open positions upon pivotal movement of the arms. The amount of pivoting movement is controlled by an adjuster and a scale is provided to give an indication of the amount of tip separation. The tips of the arms are adapted to be insertable into an incision in eye tissue and to open the incision to a predetermined dimension to permit the insertion of an ocular lens. The tips may open the incision just by a stretching of the eye tissue, for subsequent insertion of the lens, or alternatively the tips may be provided with one or two diamond blades which open the incision by a cutting of the eye tissue.