Send the link below via email or IMCopy
Present to your audienceStart remote presentation
- Invited audience members will follow you as you navigate and present
- People invited to a presentation do not need a Prezi account
- This link expires 10 minutes after you close the presentation
- A maximum of 30 users can follow your presentation
- Learn more about this feature in our knowledge base article
A History of Ophthalomoscopes
Transcript of A History of Ophthalomoscopes
In 1704 Jean Mery observed the retinal vessels of a cat were visible (if the cat was underwater!)
Before the invention of the Ophthalmoscope...
Prior to the invention of the ophthalmoscope there was very little knowledge of the eye and what was behind the pupil. Before 1810 there were many theories surrounding what made the eye appear luminous under certain conditions: Phosphorescence. The eye absorbing light during the day and giving it off at night, or even electrical qualities.
Sushruta: the father of Ophthalmology
Benedict Provost was the first person to explain that the observed luminosity of the eye came from external light sources.
Ernst Brucke gave an accurate description of why the red colour was apparent in the luminosity of the pupil. William Cumming - a young ophthalmologist at the Royal London Ophthalmic Hospital (later to become the Moorfields Eye Hospital) – published a paper stating that every eye could become luminous under the correct light conditions.
Hermann von Helmholtz
Shortly after Helmholtz produced his first ophthalmoscope, a major deficiency became apparent. There was no convenient means of correcting for presbyopia or refractive errors.
Before the Ophthalmoscope...
Prior to the invention of the Ophthalmoscope...
Invention of the Ophthalmoscope...
A History of Ophthalomoscopes
Jan Purkinje observed the fundus (back of the inside of the eye) of a dog and later a human eye using his myopic spectacles – acting as a concave mirror – these reflected light into the eye from a candle placed behind the subject. He published his findings in 1825 but they went largely unrecognised.
Charles Babbage - the mathematical genius who invented what is considered to be the first computer - was the first person to make a device that was able to look inside the eye. unfortunately when he showed his device to the eminent ophthalmologist Thomas Wharton Jones it failed to work. Sadly it would have worked if a minor change had been made to it. Babbage - disillusioned - scrapped his device.
The ophthalmoscope is a device for looking inside the eye. It allows for a good view of the 'Fundus' - the rear of the eye including the retina, the optic nerve and the optic disc. The ophthalmoscope is not just useful for checking for problems of the eye, it can also help in the diagnosis of high blood pressure and arterial disease, as well as the more familiar uses in the prescription of glasses and checking for disorders of the retina. The invention of the ophthalmoscope was considered revolutionary in the world of eye health.
The American ophthalmologist Edward Loring said 'in the whole history of medicine there has been no more beautiful episode than the invention of the ophthalmoscope, and physiology has fewer greater triumphs'. He was obviously very enthusiastic!
So what is an Ophthalmoscope?
Helmholtz was a man of many talents. Born in 1821 in Prussia (Germany) he was a scientist and philosopher who made fundamental contributions to not only optics but to physiology, electrodynamics, mathematics, and meterology. He invented the ophthalmoscope at the age of 29 and despite this success is best known for his statement on the laws of the conservation of energy.
In 1852, Egbert Rekoss, a university machinist who had made Helmholtz's original instrument, provided the essential breakthrough by adding two rotatable discs, each containing a series of lenses.
A common problem in all ophthalmoscopes when tilting the mirror toward the light was having to view the fundus obliquely through the correcting lens, as the mirror was mounted flat against the Rekoss disc. This produced a significant reduction in vision and shift of the image when viewing with higher-power lenses.
George Lindsay Johnson of London introduced an ophthalmoscope with 2 mirrors fixed to an arm that could be rotated to bring the appropriate mirror into position in front of the sight-hole.
Later variations of 3 or even 4 mirrors, back to back, were to dominate the more sophisticated devices such as the Morton ophthalmoscope for the next 40 years.
One of the key problems developers of the ophthalmoscope were faced with involved the very limited technology surrounding sources of light at the time.
Early on users had to put up with a naked flickering candle as a light source, this was soon replaced by the oil lamp within a decade.
Late in the 19th century Aimé Argand invented a device using the most common source of illumination during the second half of the 19th century, the gas lamp.
Kaiser, P. P. (2013). Ophthalmoscope. Retrieved April 22, 2015, from The Joy of Visual Perception : http://www.yorku.ca/eye/ophthal.htm
Keeler, C. (2003, June 16). A Brief History of the Ophthalmoscope. Retrieved April 24, 2015, from The Royal College of Ophthalmologists London: http://www.college-optometrists.org/filemanager/root/site_assets/oip/4-2/a_brief_history_of_the_ophthalmoscope.pdf
Keeler, C. R. (2002, February). The Ophthalmoscope in the Lifetime of Hermann von Helmholtz. Retrieved April 24, 2015, from JAMA Opthalmology: http://archopht.jamanetwork.com/article.aspx?articleid=269625
Millodot. (2009). Dictionary of Optometry and Visual Science. Retrieved April 24, 2015, from The free dictionary by Farlex: http://medical-dictionary.thefreedictionary.com/_/viewer.aspx?path=ElMill&name=F0O-01-S2958.jpg&url=http%3A%2F%2Fmedical-dictionary.thefreedictionary.com%2FOpthalmoscope
The Emile Busch Company (1928) patented a new design that made the ophthalmoscope much smaller. It could now could be hand held or mounted on a table top. Before that Swedish Nobel laureate Gullstrand produced the first handheld monocular and binocular ophthalmoscope in 1910. And then Zeiss introduced an opthalmoscope that could be worn on the head leaving the hands of the practitioner free for operating.
Royal Netherlands Ophthalmic Hospital, Utrecht. (1988). The Utrecht Ophthalmic Hospital and the development of the ophthalmoscope. Retrieved April 24, 2015, from PupMed.Gov: http://www.ncbi.nlm.nih.gov/pubmed/3046872
Tatro, P. a. (1996). ophthalmoscope. Retrieved April 24, 2015, from The free dictionary by farlex: http://medical-dictionary.thefreedictionary.com/Opthalmoscope
Williams, L. P. (2015). Hermann von Helmholz. Retrieved April 24, 2014, from Encyclopedia Britannica: http://www.britannica.com/EBchecked/topic/260507/Hermann-von-Helmholtz
A key innovation in the ophthalmoscope came with the invention of the electric incandescent light bulb, this provided a much more stable and reliable light source as well as being much brighter than previously used sources of illumination.
The principle behind the modern binoucular Ophthalmoscope
Today the ophthalmoscope can be used in two different ways. A direct ophthalmoscope produces an image at 15x magnification. It is used to examine the fundus of the eye regarding changes in the blood vessels and abnormalities in the macula. Indirect ophthalmoscopes produce a reversed image of 2-5x magnification. They need a stronger light source and are specially designed for diagnosis and treatment of retinal tears, holes and attachments. Binocular indirect ophthalmoscopes were difficult to use without a good light source but became very popular once the electric light bulb was invented.
The above image shows the principle behind the monocular direct design ophthalmoscope. The red line represents light focused from the bulb onto a patient's retina. The blue line represents light reflected from the patient's retina and projected into the examiner's eye.