Biomicroscopy: Examination external and anterior structures Flashcards
stereoscopic view
varying magnification
varying illuminations
camera/video recording or teaching tube adapters for documentation
hand held models available for bed ridden patients or screenings
different lamp models
Biomicroscopy advantages
composed of 3 systems
observation system
mechanical system
illumination (koehler) system
oculars and eyepieces
observation system
patient adjustment, mechanical locks, joystick, etc
mechanical system
the filament is imaged to the objective lens and the mechanical slit is imaged to the patients eye
illumincation Koehler system
biomicroscope
adjustable focus eyepieces
magnification dial
viewing arm
slit size, slit shape, and filter controls
variable size, shapes, color, and brightness
illumination arm
illumination comes from above
Haag-streit type
illumination comes from below
zeiss
2 convex lenses are placed one in front of the other, separated by the distance of their focal length
provides inverted image
astronomical telescope system
for higher and changable magnification a __________ telescope system is used
a convex and concave lens is used in line, separated by their focal length
galilean telescope
telescope systems produce an inverse image of the object therefor a ____ is needed to make the image erect
Prism
a porro-abbe prism is used: 2 triangular prisms
the point at which the microscope is focused, which corresponds to the point on which the light is focused (coupling effect)
parfocality
bright, even, finely focused illuminatgion with adjustable slit components: light source condenser lens system slit and other diaphragms filters projection lens reflecting mirror or prism
illumination system
controls slit width
red: aperture size
yellow: filter
vary the position of the reflecting mirror, allowing for a change in the angle of the light beam with respect to the viewing system
click stop
optical elements provide enlarged stereoscopic images
mag changes for better details )10x,16x 25x32x 40x)
provides larger working distance in front of patient which allows for manipulation
observation system
used to decrease patient discomfort
more comfortable
but makes light dimmer so doctors don’t really like
heat absorbing
used to enhance the view of blood vessels and hemmorages
also helps differentiate between retinal and choroidal lesions (choroid will disappear with this filter)
red-free filter
used for general viewing
75-80% of time used
white light
important filter
by itself or used with additional filters
used for corneal lesions and contact lens fitting
used with tonometry
cobalt blue
used w cobalt blue
either built into slit lamp or hand held
commonly used for contact lens evaluations
wratten yellow filter
clean forehead band and chin rest make sure patient an examiner are comfortable counsel patient on what to expect provide a fixation target adjust eyepieces room elimination to dim
steps before performing slit lamp evaluation
light beam and microscope are focused on the same object
direct illumination
used w direct illumination for an overall view
direct diffuse illumination
broad views of one plane
parallelpiped
“cut through” a tissue for thickness and depth
optical section
wide beam
used for general observation of anterior segment
good for: lashes, lids, caruncle, bulbar conj, etc
diffuse illumination
procedure:
use a wide beam (slit open completely)
illumination angle of 45 degrees
low magnification
adjust angle of illumination to observe the whole corena
use joystick to bring the slip lamp into focus
diffuse illumination
used to determine the depth or elevation of a defect in the corena to conjunctiva
good for:
assessing depth of FB, scars, opacities
locating which layer has an opacity
identifying the anatomical location of cataracts in the lens
etc
optic section
