Ophthalmoscope: Difference between revisions
No edit summary |
No edit summary |
||
| Line 1: | Line 1: | ||
{{CMG}} | {{CMG}} | ||
'''Associate Editor-In-Chief:''' Aarti Narayan | '''Associate Editor-In-Chief:''' Aarti Narayan | ||
| Line 6: | Line 6: | ||
The '''ophthalmoscope''' is an instrument used to examine the [[eye]]. Its use is crucial in determining the health of the [[retina]] and the [[vitreous humor]]. | The '''ophthalmoscope''' is an instrument used to examine the [[eye]]. Its use is crucial in determining the health of the [[retina]] and the [[vitreous humor]]. | ||
==Indications== | |||
In patients with [[headache]]s, the finding of swollen [[optic disc]]s, or [[papilledema]], on ophthalmoscopy is a key sign, as this indicates raised [[intracranial pressure]] (ICP) which could be due to [[hydrocephalus]], [[benign intracranial hypertension]] (aka pseudotumor cerebri) or [[brain tumor]], amongst other conditions. Cupped optic discs are seen in [[glaucoma]]. | In patients with [[headache]]s, the finding of swollen [[optic disc]]s, or [[papilledema]], on ophthalmoscopy is a key sign, as this indicates raised [[intracranial pressure]] (ICP) which could be due to [[hydrocephalus]], [[benign intracranial hypertension]] (aka pseudotumor cerebri) or [[brain tumor]], amongst other conditions. Cupped optic discs are seen in [[glaucoma]]. | ||
| Line 30: | Line 31: | ||
|- | |- | ||
| | | | ||
| '''Direct | | '''Direct ophthalmoscopy''' | ||
| '''Indirect | | '''Indirect ophthalmoscopy''' | ||
|- | |- | ||
| '''Image''' | | '''Image''' | ||
| Line 53: | Line 54: | ||
| upto the ora serata | | upto the ora serata | ||
|} | |} | ||
==[[Mydriasis|Dilatation of pupils]]== | |||
Use of [[Mydriasis|mydriatics]] allows better visualizing of the retina as the pupils constrict because of light from the ophthalmoscope. | |||
==References== | ==References== | ||
Revision as of 19:44, 29 May 2012
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor-In-Chief: Aarti Narayan
Overview
The ophthalmoscope is an instrument used to examine the eye. Its use is crucial in determining the health of the retina and the vitreous humor.
Indications
In patients with headaches, the finding of swollen optic discs, or papilledema, on ophthalmoscopy is a key sign, as this indicates raised intracranial pressure (ICP) which could be due to hydrocephalus, benign intracranial hypertension (aka pseudotumor cerebri) or brain tumor, amongst other conditions. Cupped optic discs are seen in glaucoma.
In patients with diabetes mellitus, regular ophthalmoscopic eye examinations (once every 6 months to 1 year) is mandatory 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).
There are numerous companies other than Welch Allyn that manufacture direct ophthalmoscopes, including Heine, Riester and Keeler. Ophthalmoscopes are often sold with otoscopes as a diagnostic set.
History
Although originally invented by Charles Babbage in 1847, it was not until it was independently reinvented by Hermann von Helmholtz in 1851 that its usefulness was recognized.
While training in France, Andreas Anagnostakis, MD, an ophthalmologist from Greece, came up with the idea of making the instrument hand-held by adding a concave mirror. Liebreich created a model for Anagnostakis, which he used in his practice and subsequently when presented at the first Ophthalmological Conference in Brussels in 1857, the instrument became very popular among ophthalmologists.
In 1915, Willam Noah Allyn and Frederick Welch invented the world's first hand-held direct illuminating ophthalmoscope[1], precursor to the device now used by clinicians around the world. This refinement and updating of von Helmholtz's invention enabled ophthalmoscopy to become one of the most ubiquitous medical screening techniques in the world today. The company started as a result of this invention is Welch Allyn.
Types
- Direct ophthalmoscope
- Indirect ophthalmoscope
- Binocular indirect ophthalmoscope
- Monocular indirect ophthalmoscope
| Direct ophthalmoscopy | Indirect ophthalmoscopy | |
| Image | Upright, virtual image, of approximately 15 times magnification | Inverted, reversed, direct image of 2-5 times magnification |
| Condensing lens | not too bright | bright, can be used in hazy media |
| Area in field of focus | About 2 disc diameters | About 8 disc diameters |
| Stereopsis | Absent | Present |
| Accessible fundus views | slightly beyond equator | upto the ora serata |
Dilatation of pupils
Use of mydriatics allows better visualizing of the retina as the pupils constrict because of light from the ophthalmoscope.
References
See also
External links
- Overview at bmjjournals.com
- A new digital hand held ophthalmoscope - sciencedaily.com -
cs:Oftalmoskop de:Ophthalmoskopie no:Oftalmoskop nn:Oftalmoskop sv:Oftalmoskop