The slit lamp exam examines structures in the front of the eye. A slit lamp, which is a specialized magnifying microscope, is used to examine structures of the eye (such as the cornea, iris, vitreous, and retina). The slit lamp is an energy-efficient microscope combined with a high-intensity light source that can be focused as a thin beam. The doctor will use a low-power microscope, along with a slit lamp, which is a high-intensity light.
They will look closely into your eyes. The slit lamp has different filters to obtain different views of the eyes. Some doctor's offices may have devices that capture digital images to track changes in the eyes over time. This makes it easy to use in daily clinical work for direct comparison with the view through the eyes of the slit lamp.
Biomicroscopy of the fundus with the slit lamp, as is widely practiced today, was not established until the 1980s with the introduction of the Volk +90 and +60D lenses. One reason may be that, for the slit lamp, which only offers a “bird's eye view”, the actual extension of the macular orifice is hidden by its bulging edges (see figure). Until the introduction of Volk lenses, the concept of concave lenses for viewing the fundus with the slit lamp (Littmann 1950b) had been followed, which had been introduced by Leonhard Koeppe with a contact lens (Koeppe 191 and Karl Hruby through a hand lens (Hruby 1941; Hruby 1950). Therefore, videography of the fundus with the slit lamp is a worthwhile approach, especially for the many ophthalmologists who do not have access to the latest diagnostic equipment or to an available professional photographer.
The higher the power of the scanning lens, the smaller the magnification of the image visible in the slit lamp biomicroscope (also compare with Figure 2, in the lower right part, to see the size of the area of the illuminated background). Of course, the perimetry of the fundus with the slit lamp can never be as precise as the perimetry of the fundus using the scanning laser ophthalmoscopy technique (Kaschke et al. In this case, all clinical decisions in an 8-and-a-half-year follow-up can be adequately based on slit lamp documentation. Other aperture substructures (as known by direct ophthalmoscopy) are not implemented in slit lamps.
For a structured discussion, the equipment mentioned above (converging lens, aperture) and image processing will be applied to slit lamp imaging of various parts of the fundus in the topographical order indicated below. More than 9 years of progressive excavation of the right optic disc (seen through the slit lamp with +90D fundoscopic lens with a 32x magnification) despite well-controlled intraocular pressure (for the flicker test, see the additional file). Different settings of these aperture systems were tested for their potential use for videography of the fundus with a slit lamp. Although these facts have mainly been known for many years, almost no image captured with a slit lamp or presented at scientific meetings or used in clinical practice can be found.
It is true that many new tools for documenting the fundus have come on the scene (Flittiger 201), but it is also true that contemporary ophthalmologists are spending more and more time in front of the slit lamp in the biomicroscopy of the rear segment.