Maddox (1863-1933), a British surgeon and ophthalmologist, an expert in both binocular vision and strabismus (especially strabismus). He has a high level of expertise in optical therapy and has invented a variety of devices for better eye condition research. Including the Markov rod, Markov double prism, Markov red glass, Markov cross and Markov wing. As an enthusiastic astronomy enthusiast, he also invented a lightning arrester that can be placed on stars and constellations. Maddox rod: An important and indispensable tool for binocular visual function testing. The Markov rod can be used for horizontal and vertical recessive strabismus, rotational recessive strabismus, and unequal image inspection. It has important reference value in evaluating binocular vision function and disposing of binocular vision abnormalities.