This book investigates the development and function of the Phoroptor, a crucial instrument in optometry and ophthalmology. Henry Lawrence DeZeng, a significant figure in the early 20th-century development of ophthalmic instruments, details the design and application of the Phoroptor. The text likely draws upon his expertise and potentially includes technical specifications, diagrams, and historical context surrounding its invention and adoption in clinical practice. It aims to provide a comprehensive understanding of this device's role in vision testing and correction.

This facsimile reprint of a 1922 text offers a historical and technical look at the Phoroptor, a foundational tool in vision care. The book is presented as a culturally important work, preserved for its value in understanding the evolution of ophthalmic instrumentation. Its availability in a modern, high-quality edition aims to make this specialized knowledge accessible to contemporary practitioners and historians of medicine.