A method is described for making a flush-fitting scleral lens with a central 6 mm optical zone. The essence of the method involves the replacing of the central 6 mm of the corneal portion of the mold of the eye by an appropriate spherical optical surface. A lens is then pressed out with a central posterior optic, and yet parallels the contour of the sclera and most of the cornea.
Miller D, Holmberg A, Carroll JM. A Flush Fitting Optical Scleral Contact Lens. Arch Ophthalmol. 1968;79(3):311-314. doi:10.1001/archopht.1968.03850040313016