Another fairly new method, introduced by Arif O. Khan and David Meyer in an article presented by the "American Journal of Ophthalmology", suggests the removal of the corneal epithelium first. The physician would then place a piece of filter paper soaked in platinum chloride 2% onto the area for two minutes, followed by a second piece of filter paper soaked in hydrazine 2% applied for 25 seconds. William Thomson practiced corneal tattooing in a method similar to Nieden. He used a small steel pen manufactured by Joseph Gillott, with the point converted into the cutting surface. The barrel would receive ink for the entire operation, avoiding the need to refill the ink or to recover the needle with ink. This method would avoid the disadvantages of other methods in which the ink impeded the physician's ability to control where the ink spread, which impeded the sight of the cornea to the physician. A plethora of methods exist today with varying techniques and instruments.