Slit Lamp Biomicroscopy Flashcards
3 types of illumination
- direct focal
- indirect.proximal
- retroillumination
types of direct (focal) illumination
- diffuse
- parallelpiped
- optic section
- conical beam
- specular reflection
types of indirect (proximal) illumination
- parallelpiped
- sclerotic scatter
what type of direct illumination is used for gross inspection over a maximum illuminated areas?
diffuse
what are some examples of structures observed during direct diffuse illumination
lids, lashes, lacrimal, conjunctiva
parallelepiped direct illumination is defined as any beam of light with a width between ___ mm and ___ mm
0.5mm and 2.0mm
between diffuse and optic section
what is the key feature of using parallelepiped direct illumination?
provides a 3D view (width, height, and depth
when evaluating the cornea using direct parallelepiped illumination, what is the illumination and magnification usually set to?
medium illumination and medium magnification
important structures you evaluate with parallelepiped direct illumination
cornea: edema, epithelium, endothelium, neovascularization
lens: vacuoles, cataract, Y-suture
what is the definition of direct optic section illumination
slit beam of light used to localize depth of defects
what kind of dimensional view does optic section provide?
2D (height and depth)
what is the usual widthXheight value for optic section?
0.5mm wide x 14mm high
optic section illumination is most importantly used for:
angle estimation
how can the optic section illumination be used to evaluate other structures (cornea, anterior chamber, lens)?
cornea: to determine depth of lesion
anterior chamber: to determine depth
lens: to determine depth, location, layer
the conical beam type of direct illumination is defined as:
a small round or square beam of light used to assess the status of the anterior chamber by oscillating between the cornea and the lens
you only evaluate what structure when using conical beam?
anterior chamber between the cornea (anterior boundary) and lens (posterior boundary)
uses of the conical beam are?
evaluates anterior chamber for presence of cells, flare, or pigment
the direct illumination specular reflection judges the:
quality of a surface
what is the optical definition of specular reflection?
angle of incidence of the beam of the light from the slit lamp equals the angle of reflection of light into the biomicroscope
what is unique about observation of specular reflection?
it is only observable through one ocular at a time
when is specular reflection usually performed?
on patients with suspected endothelial cell dropout
what is the reason for indirect/proximal types of illumination?
provides a softer, more scattered light to view abnormalities that would otherwise be washed out under direct illumination
some examples of uses for indirect/proximal illumination
- cornea: SEIs, corneal nerves, scars, neovascularization
- iris
- lens
sclerotic scatter is a type of indirect illumination in which light is directed:
at the limbus to scatter light internally throughout the cornea
what is unique about usage of the oculars during sclerotic scatter (indirect)?
may require the examiner to view the cornea outside of the biomicroscope in the case of central cornea clouding
how is retroillumination defined?
zone of illumination that utilizes light bounced off another structure
in retroillumination, objects that are opaque to light appear ____
dark
scars, pigment, blood vessels
in retroillumination, objects that are clear will appear ____
light
cornea, lens
in retroillumination, objects that scatter light will appear ____
light
epithelial edema, vacuoles
what are some examples of structures direct retroillumination is useful for?
- cornea
- iris: transillumination defects
- lens: posterior subcapsular cataract
