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Ophthalmoscopy, (from Ancient Greek ὀφθαλμός ( ophthalmós), meaning "eye", and σκοπέω ( skopéō), meaning "to look") also called funduscopy, is a test that allows a health professional to see inside the fundus of the eye and other structures using an ophthalmoscope (or funduscope). It is done as part of an eye examination and may be done as part of a routine physical examination. It is crucial in determining the health of the retina, optic disc, and vitreous humor.
The pupil is a hole through which the eye's interior can be viewed. For better viewing, the pupil can be opened wider (dilated; mydriasis) before ophthalmoscopy using medicated (dilated fundus examination). However, undilated examination is more convenient (albeit not as comprehensive), and is the most common type in primary care.
An alternative or complement to ophthalmoscopy is to perform a fundus photography, where the image can be analysed later by a professional.
| Condensing lens | Not required | Required |
| Examination distance | As close to patient's eye as possible | At an arm's length |
| Image | Virtual image, Erect image | Real image, inverted |
| Illumination | Not as bright; not useful in hazy media | Bright; useful for hazy media |
| Area of field in focus | About 2–8 disc diameters | About 8 disc diameters |
| Stereopsis | Absent | Present |
| Accessible fundus view | Slightly beyond equator | Up to ora serrata, i.e. peripheral retina |
| Examination through hazy media | Difficult to impossible | Possible |
Each type of ophthalmoscopy has a special type of ophthalmoscope:
In patients with , the finding of swollen (papilledema) on ophthalmoscopy is a key sign indicating raised intracranial pressure, which may be due to conditions such as hydrocephalus, benign intracranial hypertension (pseudotumor cerebri), and brain tumor. In glaucoma, cupped optic discs are seen. In patients with diabetes mellitus, regular ophthalmoscopic eye examinations (once every 6 months to 1 year) are important to screen for diabetic retinopathy, as visual loss due to diabetes can be prevented by retinal laser treatment if retinopathy is spotted early. In arterial hypertension, hypertensive changes of the retina closely mimic those in the brain and may predict cerebrovascular accidents (strokes).
Mydriatic agents are primarily considered ophthalmologist or optometrist equipment, but is used by other specialists as well, including neurologists and internists. Recent developments like scanning laser ophthalmoscopy can make good quality images through pupils as small as , so dilating the pupil is not necessary with these methods.
Later in 1851, German physiologist Hermann von Helmholtz invented the ophthalmoscope again independently. At that time, Helmholtz was a young physiology professor and wanted to demonstrate to his students why the pupil was sometimes black and sometimes light. He wrote about his ophthalmoscope in detail and demonstrated that it required three essential components (which remain true today):
Helmholtz called his instrument an Augenspiegel ('eye mirror'). The name "ophthalmoscope" only came into common use in 1854, three years after the instrument's invention.
Observing the eye's interior required alignment of the observer's vision and the light source. This was discovered by William Cumming, a young ophthalmologist at the Royal London Ophthalmic Hospital, who wrote that "every eye could be made luminous if the axis from a source of illumination directed towards a person's eye and the line of vision of the observer were coincident". To eliminate this variable, some (including Lionel Beale) created ophthalmoscopes with an attached light source.
While training in France, Greek ophthalmologist Andreas Anagnostakis came up with the idea of making the instrument hand-held by adding a concave mirror. Austin Barnett created a model for Anagnostakis, which he used in his practice and subsequently presented at the first Ophthalmological Conference in Brussels in 1857, which made the instrument very popular among ophthalmologists.
The invention of the incandescent light bulb further enabled the ophthalmoscope to be self-luminous instead of relying on an external and remote source of illumination. Alt URL The first ophthalmoscope to have an installed light bulb was created by William Dennet, who presented his invention to the American Ophthalmological Society in 1885, though it was unreliable as the light bulb's life was short and unpredictable.
The ophthalmoscope was further improved in 1915 by G.S. Crampton, who added a battery to the handle for powering the light source, thus making the instrument portable.
In 1915, Francis A. Welch and William Noah Allyn invented the world's first hand-held direct-illuminating ophthalmoscope. The company Welch Allyn started as a result of this invention. In the 2000s, the company developed a new design of ophthalmoscope called the "Panoptic". The instrument produced an image with a field-of-view five times larger than conventional direct ophthalmoscopes.
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