The document summarizes the basics of slit lamp microscopy. It describes the two main components - the slit lamp illumination system and the biomicroscope. The slit lamp can be of the Zeiss or Haag Streit type, with illumination coming from below or above, respectively. The biomicroscope is based on a compound microscope and comes in two types - Grenough and Galilean changer - that allow changing magnification. The slit lamp and biomicroscope are coupled to maintain parfocal alignment but can be dissociated for techniques like sclerotic scatter. Different illumination techniques like diffuse, focal, retroillumination and indirect are described. Gonioscopy and fundus examination are also possible using specialized lenses.
4. In the Zeiss type the illumination
comes from below
5. In the Haag Streit type the
illumination comes from above
6. In both types of illumination system
the Kohler illumination principle is
used:
The filament is imaged on to the objective lens but the
mechanical slit is imaged on to the patient’s eye
7. The biomicroscope:
based on the optics of a compound
microscope
• Two basic types:
–The Grenough type
–The Galilean changer type
12. The slit lamp and the biomicroscope
are maneouvred together on a cross
slide by means of a joystick
13. The coupling between the slit lamp
and the biomicroscope
• This is such as to make the system
“parfocal”
• i.e the focus of the slit and the focus of the
microscope are at the same point.
• This parfocality may occasionally need to
be dissociated as for example in the
technique of sclerotic scatter
14. The coupling between the slit lamp
and the biomicroscope
• This allows both the
slit and the
microscope to rotate
about the point of
focus (i.e the eye)
15. Dissociation of parfocality can be done in
“Haag Streit” type slit lamps by loosening
the sclerotic scatter knob
16. This dissociation of parfocality is
useful for indirect illumination,
sclerotic scatter and retroillumination
17. • The key to successful
examination of the
anterior segment is
knowledge of the
various methods of
lighting which can be
achieved by the slit
lamp.
53. • Fundus examination
can be done with a
slit lamp with the use
of ancillary lenses
• Ancillary lenses are
required to neutralize
the refractive power
of the cornea .
54. Use of the short reflex mirror is recommended for
posterior segment examination because the upward
projection of the long mirror blocks one of the eye
pieces when the illumination is kept at a small 3-5
degree angle from the binocular
However, the illumination beam
column must then be tilted else
the illumination beam will fall
partly outside the mirror reducing
the illumination entering the eye
