Molded scleral contact lenses may be divided into two basic types. Optical scleral contact lenses are used for improving vision, for example, in cases of keratoconus, or irregular astigmatism. Nonoptical scleral contact lenses (flush fitting scleral shells)1 are used as therapeutic devices. For example, they are helpful as surgical splints of short duration in cases requiring fornix enlargement, in cases of acute corneal ulcers, or after keratoplasty. Flush fitting shells may also be used for prolonged periods in selected cases of Stevens-Johnson syndrome, keratitis sicca, trichiasis, and indolent corneal ulcers.
Although plastic molded scleral lenses have been made since 1938,2 the optimal method for pressing a piece of plastic into its molded form is still a matter of controversy. There seems to be universal agreement on the basic method of taking a mold of an eye with a quick setting alginated gel, and then making a positive impression
MILLER D, HOLMBERG A, CARROLL J, BOYD M. Comparison of Two Methods in Molding Scleral Contact Shells. Arch Ophthalmol. 1966;76(3):422-425. doi:10.1001/archopht.1966.03850010424023