slit lamp Flashcards
slit lamp techniques are useful for?
- screening for eye complaints
- fitting contact lenses
- managing anterior and posterior eye disorders
slit lamp consists of ?
illumination and observation system
slit lamp is an important tool for the examination of the ____ and _____ segment of the eye
anterior
posterior
the observation system is a?
high resolution microscope
the illumination system is a?
focusable beam
the rheostat voltage dial can help to
vary the slit height, width, angle, intensity
what does acronym CRYND stand for?
Cobalt blue Red free Yellow Neutral density Diffuser
what does the diffuser filter do
overview of the anterior eye and adnexa
what does the yellow filter do
eliminates short wavelength light during fluoresceine examination
what does the red free filter do
enhances contrast between blood vessels and surrounding ocular structures
what does the neutral density filter do
if larger slit height/ widths are required then it reduces brightness
what does the cobalt blue filter do
used in conjunction with sodium fluorescein (exciter)
how is a sharp edge achieved in an illumination system
by using a physical aperture and optical system
describe the eyepieces in slit lamp observation system?
parallel eyepieces
can be interchanged to provide increased magnification (10x/16x)
how can magnification be modified in an observation system?
Turret= modifies magnification (6.3x, 10x, 16x, 25x, 40x)
flipper for 1x/ 1.6x magnification
what can a reticle do
added to eyepiece for assessment of ocular structure size, shape
what does the acronym RIDDSS stand for
Retro-illumination Indirect illumination Direct focal illumination Diffuse illumination Sclerotic scatter Specular reflection
diffuse illumination
low magnification high illumination wide illumination beam/ diffuser optimum beam angle 45-60º provides overview of eye and adnexa (lids, lashes, cornea, conjunctiva, iris, pupil) often used for ophthalmic photography
For ______ -______ illumination , the slit lamp ______ beam and _________ microscope are focussed at the ______ point.
It provides a ______ view of the cornea , _____ ______ and crystalline lens (or -______ lens) .
The more ______ the structure, the ______ the angle between ________ and _______ system.
direct focal illumination observation same 3D anterior chamber intraocular anterior wider illumination observation
Direct focal illumination - parallelepiped
3D view of cornea and crystalline lens at low to moderate magnification low illumination scans for fluorescein staining 1-2mm slit beam width , max height beam angle varies but optimum beam angle is 45-60º
Direct focal illumination - optic section
narrow slit beam (,0.5mm, max height)
wide angle (60º) to facilitate depth estimation
assesses depth of opacity anomaly once detected with parallelepiped beam
illumination is moderate to high
sclerotic scatter
produced by phonemenon of total internal reflection within cornea
a glow around cornea is present in a normal cornea
it is used for the presence of an opacity (central corneal oedema ) will lead to light scatter in that region
indirect illumination
practitioner views structure to the side of the directly focussed section
slit lamp is decoupled
can be used to view the cornea where the direct focal illumination would bleach the area under examination
focal corneal oedema, corneal foreign bodies
Retro illuminated
area of interest is illuminated by light behind the structure
cornea is retro illuminated by the iris
can e useful to view structures that would be bleached by DFI (gimbal vascularisation)
depending on magnification can be viewed with a coupled or decoupled system
specular reflection
provides an adequate image of surface structure/ texture (pre corneal tear film, corneal endothelium)
observation and illumination systems are at equal angles to a perpendicular line relative to the structure
high magnification (25x to 45x)
superimposition of purkinje images
