what is click stop
aka parafocal alignment/coupling
light and microscope converge on the same area of interest
what is out of click stop
light is immediately adjacent to the area of interest
what do the slit lamps basic componenets to
- evaluate the health of the ant and post segment of the eye
- assess contact lens fits
moving the joystick towards the eye enables you to focus on more _____ structures
posterior
to view flat surfaces how do yo move the joystick? how about to view convex structures?
flat: move joystick across in a straight line
convex: move joystick parallel to the convex surface
what is direct focal?
what are teh 3 types
-microscope and light beam focused on the same area
parallelepiped
optic section
conical beam
what is diffuse illumination?
what mag
what is it used to screen
what is the angle of illumination
- wide beam of light illuminating a large area
- low mag
- use: general screening of upper and lower lids, lashes, puncta, conjunctiva, no fine detail
- 45 degrees
what kind of beam does parallelepied use? angle? what can you view?
moderately side beam
angle 45
gives a broader view of conj, cornea, iris
what is optic section used to evaluate? what kind of detail?
- evaluate layers of cornea
- asses thinning/thickening of cornea
- asses ant chamber using VH
- evauluate lens
- fine detail
what is the principle behind conical beam?
tyndall phenomenon: visibility of beam of light caused by floating particles (cells) in the ant chamber
what kind of mag does conical beam use?
what should the examiner be wen using this?
where is light directed?
what kind of beam?
- high mag, high ill, and reduced room ill
- examiner should be dark adapted
- light directed through the pupil
- beam should be widest and shortest
what does conical beam asses
anterior chamber cells-WBC, RBC
flare-proteins
-presence of cells and flare is a sign of ocular inflammation: commonly in the unveal tract
-cells and flare should be graded by severity
in indirect focal illumination, how is the microscope focused?
- what do you look at?
- what is it used to observe?
microscope focused next to the light
- by looking next to the light
- by moving the light source out of “click stop” position
- used to observe fine corneal vascularization
- useful for iris pathology
how is the light reflected in retroillumination?
what are the 2 types and how are they different
light is reflected from deeper (post) structure to view more ant structure
- direct retro: observed structure is in the pathway of reflected light
- indirect: microscope is focused adjacent to the reflected beam of light (simliar to out of click stop)
in sclerotic scatter what beam is used?
what do you observe
- focus on broad, bright beam at the temporal limbus
- microscope focused on the cornea
- observe the halo around the cornea at the nasal limbus
- look at the cornea from outside of the slit lamp to view corneal edema for the best view
what is specular reflection used to examine?
type of mag?
what kind of beam?
how to position the light source?
- to examine the corneal endothelium
- high mag
- side parallelepiped
- position the light source so that the corneal light reflection is captured through one of the oculars
what are the 2 types of filters used? what are they used for?
- cobalt blue
- goldmann tonometry
- tear film assessment
- corneal staining - red free
- differentiate crescents
- cws
- choroidal nevus
what is the range of mag used
6-40x
what can high mag be very useful to assess
corneal scar/ulcers ant chamber infl guttata iris neo pigment dispersion on lens/corneal endothelium pseudoexfoliation
if what you’re seeing doesn’t look right, what are the 3 questions to ask yourself
- is the pd adjusted for you
- are each of the eyepieces adjusted appropriately for you
- is the lamp out of parafocal alighment
if you cant see anything from the lsit lamp, what questions to ask yourself
- is the width so narrow it is closed?
- are you btwn aperature settings?
- is the microscope so far from the pt that is way out of focus?
- are you btwn mag settings?
- is the bulb burned out?
- is the slit lamp plugged in and turned on? is it wired through the stand?
