A momentous development in the field of clinical ophthalmology occurred in the mid-19th century when the invention of the direct ophthalmoscope took place. The ability to shine focused illumination on the eye’s adnexa and the human retina was to forevermore greatly facilitate the diagnosis and treatment of many ocular disorders.
A brief history of the direct ophthalmoscope
It is not widely known that it was the English-born Cambridge mathematician Charles Babbage FRS (1792-1871) who first devised and constructed an instrument for examining the retina.1 Babbage had a particular fascination for the design and implementation of scientific instruments and had become interested in eyes as a result of his own ocular problems, which he described as ‘irregular vision’.1
Babbage’s early ophthalmoscope is said to have consisted of a tube with an internal mirror that was angled such that external light could be reflected into a patient’s eye. A small aperture – or sight-hole – in the mirror allowed the observer to view the subject’s retina. Unfortunately, the British ophthalmology authorities of the time (1847) showed disinterest and even antipathy towards the invention and Babbage’s ophthalmoscope progressed no further.1
It was to the German-born physiologist and physicist Hermann von Helmholtz (1821-94), that credit for inventing the first ophthalmoscope was finally given. Born into an academic family, Helmholtz graduated from the Wilhelm Medical Institute, Berlin, in 1843.2 A true polymath he had already developed an interest not only in medicine but also in many other subjects, including physiology, optics, electrodynamics, mathematics and human anatomy.
It was during his tenure as professor of anatomy and physiology at the University of Konigsberg (1849-55) that Helmholtz became interested in the workings of the human eye. In particular, he wished to demonstrate to his students that light entering a subject’s pupil is reflected back to its source.
Thereby explaining why the pupil sometimes appeared black and at other times light. Thus in 1850, while studying the emission of reflected light from the eye (and working independently of Babbage) Helmholtz invented the first functional ophthalmoscope.3
Although this early instrument was of a somewhat crude design consisting of pieces of cardboard, candles, glue and several glass microscopic slides, Helmholtz demonstrated that in order to view the retina it was necessary for any ophthalmoscope to satisfy three basic conditions, ie:
- There has to be a source of illumination.
- A method of reflecting light into the subject’s eye.
- The eyes of the observer and the subject have to be rendered emmetropic, by optical means, in order to create a clear retinal image.3
Originally described as an ‘augenspiegel’ (eye mirror) the term ‘ophthalmoscope’ (eye observer) did not come into use until 1854.3 Keen to inform the medical and scientific community of his invention, in 1850 Helmholtz initially gave an oral presentation to the Physical Society of Berlin.
A few months later, in 1851, he gave another presentation, this time to the influential Society for Scientific Medicine of Konigsberg. At around the same time, Helmholtz published a 43 page monograph containing a detailed account of his invention.4 Unlike Babbage, Helmholtz and his ophthalmoscope received an appreciative welcome from leading ophthalmologists, who were quick to realise the considerable benefits of obtaining a view of the living retina.
Inevitably, over the ensuing decades, the original design by Helmholtz underwent many improvements and modifications to become the sophisticated instrument employed by clinicians today. The direct ophthalmoscope remains one of the most useful devices available to all those investigating the health of the human eye.
A vintage ophthalmoscope
The compact direct ophthalmoscope illustrated in figures 1a and 1b (pictured top) bears the single inscription; ‘HEINE’, indicating the latter as the source of its manufacture. The accompanying protective carrying case illustrated in figure 1b is further inscribed; ‘HEINE miniset’. The instrument most likely dates from the late nineteen-sixties or the early 1970s.5
This Heine pocket ophthalmoscope was kindly given to the author over a decade ago by the late William Moore, FBOA. Moore was a highly regarded ophthalmic optician who, for many years, worked from his renowned house practice in the west of Scotland town of Kirkintilloch. During his early years in optometry, the author often had occasion to be very grateful to Bill Moore for his friendly advice and mentorship.
Based in the German town of Gilching, near Munich, Heine Optotechnik is today the designer and manufacturer of high quality primary diagnostic devices and instruments including ophthalmoscopes, otoscopes and dermatoscopes. The company was founded in the immediate post-war year of 1946 by Helmut A Heine (1916-2007), a German graduate physicist with a passion to become involved in the field of medical science.
Due to a shortage of materials, early instruments were said to have been manufactured using recycled cartridge cases. Helmut A Heine remained on the company’s board of management until he retired in 2004 at the age of 88. The business still remains in family ownership.6
The Heine pocket ophthalmoscope featured in figures 1a and 1b is of robust construction, yet is lightweight, slimline and portable, making it useful for consulting room, ward round and domiciliary applications. Remarkably, with the insertion of appropriate batteries, the author found the instrument still to be in good working order.
Some important specifications of the ophthalmoscope are detailed in table 1.
Some important specifications of the protective carrying case are detailed in table 2.
A brief guide to the features annotated in figures 1a & 1b is now given.
The ophthalmoscope is equipped with five diagnostic beams, or apertures, selected by the aperture selector wheel, indicated on figure 1a by the letter D.
- A small circular white beam for macular examination.
- Intermediate circular white beam for retinal examination.
- Large sized circular white beam for general examination of internal and external eye.
- Vertical white slit for detecting retinal elevations and depressions. Also to be used in estimating the anterior chamber depth.
- Circular green (red free) filter for enhanced examination of retinal vasculature and haemorrhages.
Conclusion
The invention of the direct ophthalmoscope dramatically improved the clinical practice of ophthalmology. The instrument described in this article may be said to claim its distant lineage from the pioneering work of Babbage and Helmholtz.
The eminent American ophthalmologist Edward Loring (1837-88) summed up the importance of the direct ophthalmoscope when he stated in the introduction to volume one of his textbook; A Textbook on Ophthalmology, (published 1886): ‘In the whole history of medicine there is no more beautiful episode than the invention of the ophthalmoscope, and physiology has few greater triumphs.’7
Acknowledgement
The author wishes to express his gratitude to Mr Neil Handley, curator of the British Optical Association Museum at the College of Optometrists, London, for his assistance in the researching of this article.
- Andrew King is an independent prescriber optometrist and contact lens practitioner working in private practice in the Glasgow area.
References
- https://www.aao.org/senior-ophthalmologists/scope/article/man-who-almost-invented-ophthalmoscope. Last accessed March 2024
- https://philosophynow.org/issues/129/Hermann_von_Helmholtz_1821-1894. Last accessed March 2024
- https://www.college-optometrists.org/coo/media/media/oip/volume%2004,%20issue%202/a-brief-history-of-the-ophthalmoscope-oip-volume-4-issue-2-2003-cr-keeler.pdf?ext=.pdf. Last accessed March 2024
- https://jamanetwork.com/journals/jamaophthalmology/article-abstract/622045. Last accessed March 2024
- Handley, Neil, 2024. Personal correspondence with the author
- https://www.heine.com/en/about-us/philosophy/the-history-of-heine. Last accessed March 2024
- Loring, EG. (1892), Textbook of Ophthalmology, Part One. Henry Kimpton, London, UK