What is meaning of +- 4D in eye for job application requirement

power 4dThe power to be a 4th-dimensional entity. Variation of Dimensional Entity. Not to be confused with Temporal Entity. 4D Physiology Fourth Dimensional Physiology New God Physiology (FourthAFL's OPM5 and OPM4 Optical Power Meters for accurate fiber optic testing. Featuring Wave ID, rugged desn, and compatibility with various networks. ... -4D (Filtered-InGaAs) for hh