The progress of scotometry has in my opinion been materially retarded by the lack of a simple and inexpensive instrument. While it is admitted that the ideal scotometer probably cannot be devised, still the inadequacy of the simple models available and the expensiveness of the more complete instruments leave a gap which can be bridged. I have endeavored to meet this need by designing the instrument about to be described.
In developing the presented instrument, every effort was made to minimize manufacturing costs in an effort to keep the retail price as low as possible. The dimensions were so selected as to permit the use of standard equipment and to make unnecessary departure from the generally accepted technic.
Thus, the illuminating system was designed about a standard, commercial "show case," light bulb. The cord, connector and light switch are standard products. The tangent surface was so proportioned that it could
EVANS JN. THE NEW SCOTOMETER. Arch Ophthalmol. 1941;25(3):445–449. doi:10.1001/archopht.1941.00870090069007