Ophthalmoscopy is ophthalmic procedure in which examine the fundus of eye by using the ophthalmoscope. The fundus examination done with three different method as follows:
1. Distance Direct ophthalmoscopy
2. Direct ophthalmoscopy
3. Indirect ophthalmoscopy
Direct ophthalmoscopy
• It was invented by Babbage in 1848 and reinvented and popularized by von Helmholtz in 1850.
• It should be performed from as close to the patient’s eye as possible (ideally 15.4 mm)
• Image formed by direct ophthalmoscopy is erect, virtual and 15 times magnified in emmetropes (more in myopes and less in hypermetropes).
Distant direct ophthalmoscopy
• It is performed from a distance of 20-25 cm
• It is useful in detecting opacities in the media of the eye, a hole in the iris, a detached retina and a subluxated lens.
• The black shadow produced by an opacity in the pupillary plane remains stationary, that in front of the pupillary plane moves in the direction of the movement of the eyeball and that behind it will move in opposite direction.
Indirect ophthalmoscopy
• It was invented by Nagel in 1864
• In it the examining eye is made myopic by placing a strong convex lens in front of patient’s eye
• It is performed from a distance of an arm’s length (60-75 cms)
• Image inindirect ophthalmoscopy is form between the convex lens and examiner’s eye and it is real, inverted and about 5 times magnified with +13D lens
• Magnification of the image does not depend upon the refractive error of the observer’s eye but depends upon:
• Power of convex lens used
• Refractive error of the observed eye
• Position of the convex lens in relation to the eye.