Slit Lamp Techniques and Filters Flashcards
What is Diffuse illumination used to view ? And how would you carry this out using a slit lamp?
- Look at general features , ocular structures - ADNEXA
lids , lashes -tarsal gland and lacrimal ducts , conj - bulbar and palpebral , limbus sclera , cornea
- Low Mag , low illumination , wide beam diffuser for even illumination
What is Direct illumination used to view ? And how would you carry this out using a slit lamp?
Used to view structure directly lit by beam - corneal sections , lens section , van herricks
Vary beam width between optic and parallelepiped , beam angled from side , vary mag
What is InDirect illumination used to view ? And how would you carry this out using a slit lamp?
Focus in same plane as direct illumination
move eyes not slit lamp - certain structures show up better against dark background , corneal opacities?
What is Retroillumination used to view ? And how would you carry this out using a slit lamp?
Light reflected off posterior structures to view anterior .
Useful to view limbal vascularisation , pigment of endo and deposits on CL
alter angle of direct beam to separate direct and retro beams
What is Sclerotic Scatter used to view ? And how would you carry this out using a slit lamp?
Central cornea - look for oedema , foreign body
focus microscope on corneal apex , uncouple illumination and direct on limbus , widen beam and increase illumination - circle
What is Specular reflection used to view ? And how would you carry this out using a slit lamp?
established by separating beam and microscope by equal angles ,angle of illuminator to the microscope must be equal and opposite
view integrity of corneal and lens surface , corneal endo?
bright , 40x mag
Parallelepiped is ..
rectangular shaped , 2-4mm , good for general view of cornea
Optic section is …
thinnest beam width , good to look at different layers of cornea , widen beam = more depth , 45-60o+
Lens section - 15-25o - Look at y sutures , blue dot catarcacts , purkinje 3+5
Pencil/Conical Beam is ..
Look for inflammation in anterior chamber , 1mm wide and 3mm high
Cobalt Blue symbol and use
Blue filled circle
Enhances view of Nafl - Typically used for nafl staining and goldmann tonometry
Red Free symbol and use
Green filled circle
used to enhance view of blood vessels and haemorrhages
neutral density symbol and use
circle with hashed lines
decreases maximum brightness for photosensitive pts
Heat Absorbing symbol and use
Built in
decreases pt discomfort
Yellow filter
yellow filled circle
contrast enhancement when using cobalt blue and nafl
What is Van Herricks used for and how would you carry this out on a patient using a slit lamp?
used to estimate/measure the angle of the anterior chamber to determine if patient is at risk of angle closure
Optic section , viewing angle 60 degrees
Recall the van herricks grading system
Notes
When conducting Van herricks where should measurement be taken from
temporal limbus but also measure nasal limbus - narrower angle to be considered
Briefly explain how you would instil Nafl into a patient
Hygiene
wet end of strip with nafl - close the bottle
tilt head back - ask pt to look up to one side away from you
touch flat edge against lower bulbar or temporal bulbar conj
ask pt to blink few times
When instilling nafl what should you be careful of ?
not contaminate the saline bottle
not to wet strip with water as psuedomonas lives in water and has affinity for nafl
You have instilled Nafl into a pt and would like to view the tear film
briefly describe how you would do this
cobalt blue filter bright illumination low mag diffuse or wide parallelepiped beam wratten filter
When assessing the tear break up time of a patient what is considered to be normal and abnormal?
normal - more than 10 sec
marginal - between 5 and 10
low 0 less than five sec
Why do lid eversion
to assess redness and roughness of upper palpebral conj - should be smooth tarsal plate
explain how to conduct a lid eversion on a patient
ask pt to look down
hold lashes and pull away slowly from globe of eye
cotton bud placed vertically on lid crease
push bud down sligtly and at the same time lift the eye up
state two conditions that can be found when doing a lid eversion
giant papillary conjunctivitis GPC
Lid wiper epitheliopathy
State some causes of GPC
- allergy to CL or chemicals used to clean them
- deposits of protiens on cl
- cl rubbing against eyelid
What is GPC and what tx could you give to a pt who has this?
When the inside of lid becomes red , swollen , and irritated
- tx = avoid cl wear , limit amount of time wearing eyedrops via gp to reduce itching , swelling
What is lid wiper epitheliopathy
small tissue posterior to the MG
responsible for physcially wiping along ocular surface during blinking
during poor tear film = increase friction between LWE and OS
sx of LWE
dryness , grittiness , irritation , burning
