In patients with headaches, the finding of swollen optic discs, otherwise known as papilledema, on ophthalmoscopy is a key sign. This indicates increased intracranial pressure (ICP) which could be a result of hydrocephalus, benign intracranial hypertension (aka pseudotumor cerebri), or a brain tumor. Cupped optic discs are seen in glaucoma.
In patients with diabetes mellitus, regular ophthalmoscopic eye examinations every 6 months to every year is mandatory to screen for diabetic retinopathy. Visual loss due to diabetes can be prevented by retinal laser treatment if retinopathy is spotted early.
There are numerous companies other than Welch Allyn that manufacture direct ophthalmoscopes, including Heine, Riester and Keeler. Ophthalmoscopes are often sold with an otoscopes as a diagnostic set for physical exams.
While training in France, Andreas Anagnostakis, MD, an ophthalmologist from Greece, brought forth 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, 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.
- 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|
|Accessible fundus views||slightly beyond equator||up to the ora serata|
Use of mydriatics allows better visualizing of the retina as the pupils constrict due to of light from the ophthalmoscope.