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The satisfactory fitting of contact lenses became a possibility when J. Dallos, in 1933, discovered the feasibility of making molds of the living human eye with Pollner's negocoll.
The disadvantages of the use of negocoll involve primarily physical factors, such as the time consumed in preparation. The boiling for liquefaction takes almost an hour. The hot liquid negocoll must be transported in a thermos jar and subsequently cooled in a glass beaker. With constant agitation with a stirring thermometer, it is cooled to an exact temperature, at which it must be immediately placed on the eye. The slight chemosis produced by the heat of the liquid negocoll (106 F.) and the slight sting experienced by the patient after the mold has been removed, while not of much consequence, are also undesirable.
One of my students, who has made a hobby of contact lenses, observed a technic for the molding of
THEODORE E. OBRIG. A NEW OPHTHALMIC IMPRESSION MATERIAL. Arch Ophthalmol. 1943;30(5):626–630. doi:10.1001/archopht.1943.00880230058007