Ophthalmoscopy, 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
An eye examination, commonly known as an eye test, is a series of tests performed to assess Visual acuity, vision and ability to Focus (optics), focus on and discern objects. It also includes other tests and examinations of the human eye, eyes. ...
and may be done as part of a routine
physical examination
In a physical examination, medical examination, clinical examination, or medical checkup, a medical practitioner examines a patient for any possible medical signs or symptoms of a Disease, medical condition. It generally consists of a series of ...
. It is crucial in determining the health of the
retina
The retina (; or retinas) is the innermost, photosensitivity, light-sensitive layer of tissue (biology), tissue of the eye of most vertebrates and some Mollusca, molluscs. The optics of the eye create a focus (optics), focused two-dimensional ...
,
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
eye drops (
dilated fundus examination). However, undilated examination is more convenient (albeit not as comprehensive), and is the most common type in
primary care
Primary care is a model of health care that supports first-contact, accessible, continuous, comprehensive, and coordinated person-focused care. It aims to optimise population health and reduce disparities across the groups by ensuring equitable ...
.
An alternative or complement to ophthalmoscopy is to perform a
fundus photography, where the image can be analysed later by a professional.
Types
There are two major types of ophthalmoscopy:
* direct ophthalmoscopy, which produces an upright (unreversed) image of approximately 15× magnification
* indirect ophthalmoscopy, which produces an inverted (reversed) image of 2–5× magnification
Each type of ophthalmoscopy has a special type of ophthalmoscope:
* Direct ophthalmoscopy uses the direct ophthalmoscope, an instrument the size of a small flashlight with several lenses that can magnify up to about 15 times.
This type of ophthalmoscope is most commonly used during a routine physical examination. The pan-ophthalmoscope has a larger primary lens with a variable focusing, allowing for a wider field-of-view.
* Indirect ophthalmoscopy uses the indirect ophthalmoscope, an instrument that has a light attached to a headband, in addition to a small handheld lens. It provides a wider view of the inside of the eye. Furthermore, it allows a better view of the
fundus of the eye, even if the lens is clouded by
cataract
A cataract is a cloudy area in the lens (anatomy), lens of the eye that leads to a visual impairment, decrease in vision of the eye. Cataracts often develop slowly and can affect one or both eyes. Symptoms may include faded colours, blurry or ...
s.
[ An indirect ophthalmoscope can be either monocular or binocular. It is used for peripheral viewing of the retina.
]
Medical uses
Ophthalmoscopy is done as part of a routine physical or complete eye examination, mainly by optometrists and ophthalmologists. It is used to detect and evaluate symptoms of various retinal vascular diseases and eye diseases.
In patients with headache
A headache, also known as cephalalgia, is the symptom of pain in the face, head, or neck. It can occur as a migraine, tension-type headache, or cluster headache. There is an increased risk of Depression (mood), depression in those with severe ...
s, the finding of swollen optic discs ( 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 tumors. In glaucoma, cupped optic discs are seen. In patients with diabetes mellitus
Diabetes mellitus, commonly known as diabetes, is a group of common endocrine diseases characterized by sustained hyperglycemia, high blood sugar levels. Diabetes is due to either the pancreas not producing enough of the hormone insulin, or th ...
, 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).
Dilating the pupil
During ophthalmoscopy, the pupil constricts due to light from the ophthalmoscope. To allow for better inspection of the posterior eye through the pupil, it is often desirable to dilate (enlarge) the pupil by applying a mydriatic agent (e.g. tropicamide), or by reducing the ophthalmoscope's brightness, which may slightly increase natural mydriasis.
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.
History
Early models
The first instrument for looking into the eye was first invented in 1847 by British inventor Charles Babbage
Charles Babbage (; 26 December 1791 – 18 October 1871) was an English polymath. A mathematician, philosopher, inventor and mechanical engineer, Babbage originated the concept of a digital programmable computer.
Babbage is considered ...
. However, he was unable to obtain an image with the instrument when showing it to ophthalmologist Thomas Wharton Jones, and thus became discouraged to proceed further. The instrument is described by Jones as follows:
Later in 1851, German physiologist Hermann von Helmholtz
Hermann Ludwig Ferdinand von Helmholtz (; ; 31 August 1821 – 8 September 1894; "von" since 1883) was a German physicist and physician who made significant contributions in several scientific fields, particularly hydrodynamic stability. The ...
invented the ophthalmoscope again independently. At that time, Helmholtz was a young physiology
Physiology (; ) is the science, scientific study of function (biology), functions and mechanism (biology), mechanisms in a life, living system. As a branches of science, subdiscipline of biology, physiology focuses on how organisms, organ syst ...
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):
* a source of illumination (Helmholtz used a candle)
* a method of reflecting the light into the eye
* an optical method for correcting an unsharp image of the fundus
Helmholtz called his instrument an ('eye mirror'). The name "ophthalmoscope" only came into common use in 1854, three years after the instrument's invention.
Later improvements
Helmholtz's first ophthalmoscope could not correct for refractive errors in the patient and/or the observer. This limitation was solved in 1852 by Helmholtz' machinist, Egbert Rekoss, who added two rotatable discs that each contained a few lenses. These wheels of lenses were superior to other early opthalmoscopes which used separate individual lenses that were inconvenient to change. The discs are known as the "Rekoss Disc" and continue to be used on most hand-held ophthalmoscopes today.
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
Brussels, officially the Brussels-Capital Region, (All text and all but one graphic show the English name as Brussels-Capital Region.) is a Communities, regions and language areas of Belgium#Regions, region of Belgium comprising #Municipalit ...
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. 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.
Etymology and pronunciation
The word ''ophthalmoscopy'' () uses combining forms of '' ophthalmo-'' + '' -scopy'', yielding "viewing the eye". The word ''funduscopy'' () derives from '' fundus'' + '' -scopy'', yielding "viewing the far inside". The idea that ''fundus'' can and should correspond to a combining form ''fundo-'' drives the formation of an alternate form, ''fundoscopy'' (''fundo-'' + ''-scopy''), which is the subject of a descriptive-versus- prescriptive difference in acceptance. Some dictionaries enter the ''fundo-'' form as a second-listed variant, but others do not enter it at all, and one prescribes its avoidance with a usage note.
See also
* Charles Schepens
* Retinoscope
* Scanning laser ophthalmoscopy
References
External links
Ophthalmoscopy on Medlineplus
Ophthalmoscopy on WebMD
Overview at bmjjournals.com
about different types of ophthalmoscopy
{{Authority control
Diagnostic ophthalmology
Medical equipment
Ophthalmic equipment