At the dawn of the 20th century, ophthalmology was becoming a distinct and rapidly advancing specialty. Manual of the Diseases of the Eye by Dr. Charles H. May emerged as one of the most widely used and translated ophthalmic manuals of the era. First published in 1900, the manual was designed as a compact, richly illustrated reference for medical students and general practitioners—many of whom still practiced across broad fields of medicine.

By the time of this sixth edition in 1909, the book had already been translated into six languages (German, French, Dutch, Italian, Spanish, and Japanese), reflecting its global influence. It provided crucial guidance on diagnosing and managing eye diseases in a time before antibiotics, routine eye surgery, or modern diagnostic imaging.

The book’s color plates—rare and expensive to produce—offered invaluable visual instruction in recognizing conditions like iritis, cataracts, glaucoma, and retinal disease. These visual aids helped bridge the gap between textbook learning and clinical experience in an age when many physicians trained primarily through lectures and apprenticeships.

Dr. May himself was a well-known educator associated with Columbia University and several major New York hospitals. His manual helped standardize ophthalmic education and reflects the increasing emphasis on clinical specialization and visual diagnosis in early 20th-century medicine.