The Ophthalmoscope and Hermann von Helmholtz

In 1850, Hermann von Helmholtz invented the ophthalmoscope and revolutionized ophthalmology. The ophthalmoscope, the most important invention for ophthalmologist clinicians, is an instrument that allows the ophthalmologist to look inside a person’s eye and see the details of the living retina. Ophthalmoscopes allow physicians to diagnose eye diseases and prevent blindness. Hermann von Helmholtz was born in 1821 in Pottsdam, Germany. He was one of the great scientific minds of the 19th century whose accomplishments were in both medicine and science. In 1850 Helmholtz prepared an experiment for his physiology students to demonstrate the law of conservation of energy. For the experiment Helmholtz constructed a crude instrument made of cardboard, glue and microscope glass plates. This device was the predecessor of the ophthalmoscope used today. Helmholtz’s experiment showed that light entering the pupil is reflected back to its source. Furthermore, the light follows the same path out of the eye as it took entering the pupil. Using his makeshift ophthalmoscope, Helmoltz could place his eye in the path of the rays of light entering and leaving the patient’s eye, thereby allowing the patient’s retina to be seen. Helmholtz was not the first person to look at the living retina or the first person to fashion a device for viewing it. Johannes Purkinje had made the discovery in 1823 and Charles Babbage had fashioned an ophthalmoscope similar to Helmholtz’s design in 1847. However, neither discovery was well known and Helmholtz created his ophthalmoscope without the benefit of their knowledge. Unlike his predecessors, Helmholtz publicized his findings and the ophthalmoscope began to be manufactured. Helmholtz had many great accomplishments other than the ophthalmoscope, including his mastery and definition of physiological optics, theory of heat and energy, theories of hearing and the phenomenon of color and accommodation. Helmholtz earned many significant awards for his work, including being awarded the addition of the suffix "von" to his name. This honor, which he received from Kaiser Wilhem I, is similar to that of being knighted and one that can be inherited by descendants. Special thanks for this exhibit go to Spencer E. Sherman, MD.