AN INEXPENSIVE SLIT LAMP

All opthalmologists realize the value of the slit lamp, but the cost makes many forego its use. The inexpensive lamp described hereafter has given good service in my office. THEORY OF THE SLIT LAMP The slit lamp sold commercially consists essentially of five parts : a concentrated filament lamp, a condenser, a slit, an objective lens and a microscope. The condenser focuses the image of the filament on the objective lens ; the objective lens focuses the image of the slit on the cornea, and the microscope furnishes an enlarged image of the cornea. The slit may be any distance from the condenser on the side of the objective lens but is placed close to it, just far enough away so that dust particles on the condenser will be out of focus when the slit is in focus on the cornea (Ain the accompanying figure). EXAMINATION LAMP A common type of