Slit Lamp Techniques and Filters

Question 1

What is Diffuse illumination used to view ? And how would you carry this out using a slit lamp?

Answer 1

• 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

Question 2

What is Direct illumination used to view ? And how would you carry this out using a slit lamp?

Answer 2

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

Question 3

What is InDirect illumination used to view ? And how would you carry this out using a slit lamp?

Answer 3

Focus in same plane as direct illumination

move eyes not slit lamp - certain structures show up better against dark background , corneal opacities?

Question 4

What is Retroillumination used to view ? And how would you carry this out using a slit lamp?

Answer 4

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

Question 5

What is Sclerotic Scatter used to view ? And how would you carry this out using a slit lamp?

Answer 5

Central cornea - look for oedema , foreign body
focus microscope on corneal apex , uncouple illumination and direct on limbus , widen beam and increase illumination - circle

Question 6

What is Specular reflection used to view ? And how would you carry this out using a slit lamp?

Answer 6

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

Question 7

Parallelepiped is ..

Answer 7

rectangular shaped , 2-4mm , good for general view of cornea

Question 8

Optic section is …

Answer 8

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

Question 9

Pencil/Conical Beam is ..

Answer 9

Look for inflammation in anterior chamber , 1mm wide and 3mm high

Question 10

Cobalt Blue symbol and use

Answer 10

Blue filled circle

Enhances view of Nafl - Typically used for nafl staining and goldmann tonometry

Question 11

Red Free symbol and use

Answer 11

Green filled circle

used to enhance view of blood vessels and haemorrhages

Question 12

neutral density symbol and use

Answer 12

circle with hashed lines

decreases maximum brightness for photosensitive pts

Question 13

Heat Absorbing symbol and use

Answer 13

Built in

decreases pt discomfort

Question 14

Yellow filter

Answer 14

yellow filled circle

contrast enhancement when using cobalt blue and nafl

Question 15

What is Van Herricks used for and how would you carry this out on a patient using a slit lamp?

Answer 15

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

Question 16

Recall the van herricks grading system

Answer 16

Notes

Question 17

When conducting Van herricks where should measurement be taken from

Answer 17

temporal limbus but also measure nasal limbus - narrower angle to be considered

Question 18

Briefly explain how you would instil Nafl into a patient

Answer 18

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

Question 19

When instilling nafl what should you be careful of ?

Answer 19

not contaminate the saline bottle

not to wet strip with water as psuedomonas lives in water and has affinity for nafl

Question 20

You have instilled Nafl into a pt and would like to view the tear film
briefly describe how you would do this

Answer 20

cobalt blue filter 
bright illumination 
low mag
diffuse or wide parallelepiped beam 
wratten filter

Question 21

When assessing the tear break up time of a patient what is considered to be normal and abnormal?

Answer 21

normal - more than 10 sec
marginal - between 5 and 10
low 0 less than five sec

Question 22

Why do lid eversion

Answer 22

to assess redness and roughness of upper palpebral conj - should be smooth tarsal plate

Question 23

explain how to conduct a lid eversion on a patient

Answer 23

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

Question 24

state two conditions that can be found when doing a lid eversion

Answer 24

giant papillary conjunctivitis GPC

Lid wiper epitheliopathy

Question 25

State some causes of GPC

Answer 25

• allergy to CL or chemicals used to clean them
• deposits of protiens on cl
• cl rubbing against eyelid

Question 26

What is GPC and what tx could you give to a pt who has this?

Answer 26

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

Question 27

What is lid wiper epitheliopathy

Answer 27

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

Question 28

sx of LWE

Answer 28

dryness , grittiness , irritation , burning