UNIT THREE - Slit lamp Flashcards
FEATURES OF THE BIOMICROSCOPE:
Microscope
- binocular for depth perception
- various magnifications
- PD adjustments
FEATURES OF THE BIOMICROSCOPE:
Light source
- focusable
- adjustable width and height
- various filters (white,diffuse,ultraviolet,and red-free)
FEATURES OF THE BIOMICROSCOPE:
Other features
- joy stick for easy focusing
- height adjustment
- fixation light
- adjustable chin rest
- eye level mark
SLIT LAMP SET UP STEPS 1-8
- Set oculars on zero
- Set microscope on lowest mag
- Click light source into center position
- Wipe chin rest and headrest
- Orient patient and adjust eye level
- With the joystick, move the base of the instrument all the way to the left and all the way in (towards the patient)
- Turn in power, observe light at patients outer can thus
- Make all necessary height, width and color adjustments to the slit.
Diffuse
Light is thrown out of focus so it spreads over a large portion of the eye.
Uses of diffuse illumination
- lens position and movement
- surface wettability of the cornea or contact lens
- tear break up time
- gross corneal staining
- blink reflex
Direct
Parallelpiped and Optical Section
Light is focused into a sharp slit of 2mm or less.
Parallelpiped is what type of illumination?
Direct
What is parallelepiped?
A 1-2mm slit gives a parallelepiped section that separates the anterior and posterior cornea.
Parallelepiped is good for getting detailed look at
- corneal staining
- corneal opacities and infiltrates
- endothelial deposits
- deposits and scratches on the lens surface
Optical section is what type of illumination?
Direct
What is optical section?
A narrow slit that allows the observer to see individual layers of a transparent structure.
Optical section is used to
- determine which layer of the cornea is involved
- detect irregular topography
- view the lens/cornea relationship
Specular reflection is a variation of what illumination?
Direct
What is specular reflection?
When the lamp and microscope are at equal angles to the midline, a smooth transparent surface will reflect a mirror image of the lamp bulb.
(If not smooth, viewer sees the texture of the surface rather than the mirror image)
Specular reflection is useful for detecting
- hazy lenses
- fine epithelial edema
- endothelial cells
- surfaces of the crystalline lens
Indirect
Retroillumination and sclerotic scatter
Set up like parallelepiped but the viewer looks to the side of the slit instead of directly into it.
Indirect is very effective for inspecting opaque structures such as
- lids and lashes
- sclera and conjunctiva
Retro illumination is apart of which illumination?
Indirect
What is retro illumination?
Uses reflected light from the iris or retina to backlight something opaque or translucent in the cornea.
The examiner sees the shadowed side of the object against the bright background.
Retro illumination can be used for viewing
- corneal vascularization and scarring
- edema, microcysts
- deposits on the contact lens or cornea
Sclerotic scatter is apart of what illumination?
Indirect
What is sclerotic scatter ?
A halo effect is produced when a bright beam is directed toward the limbus at a wide angle.
The halo is caused by light being reflected internally between the corneal epithelium and endothelial.
The classic use for sclerotic scatter is the detection of
Patch edema
PREFITTING EXAM:
Without flourescein inspect
- lid margins and lashes
- inside lower lid
- sclera and conjunctiva ( all quadrants )
- limbus
- all layers of the cornea
- iris,pupil,crystalline lens
PREFITTING EXAM:
With fluorescein check
- tear break up time
- integrity of the corneal epithelial
- inside upper lid
FOLLOW UP EXAM:
Without fluorescein view
- lens position and movement
- limbus
- all layers of the cornea
- sclera and conjunctiva
- lids
- contact lens surface
FOLLOW UP EXAM:
With fluorescein observe
- RGP fluorescein pattern
- RGP lens/cornea relationship
- integrity of the epithelium
