MUCH OF the difficulty in performing routine electroretinography has been due to the discomfort of the contact lens electrode and, to a greater degree, of the speculum recommended by Karpe.
In an effort to overcome this difficulty, the illustrated lens was devised. It is a conventional scleral type contact lens, 24 by 25 mm., with two tubular tunnels projecting from the convex surface. These are 2 mm. in diameter and 10 mm. long. One contains the silver-silver chloride electrode and the joint by which the electrode is attached to a wire lead, which connects to the input of the ERG machine. The second tunnel is hollow and is used, after the lens is in place, to fill the lens with isotonic saline in a methylcellulose solution.
A large part of the discomfort of the test as previously performed was produced by the manipulation required to fill the lens after insertion
JACOBSON JH. A NEW CONTACT LENS ELECTRODE FOR CLINICAL ELECTRORETINOGRAPHY. AMA Arch Ophthalmol. 1955;54(6):940. doi:10.1001/archopht.1955.00930020946021