Lecture 8: Slit Lamp Exam Intro and Illumination Techniques

patient observation occurs throughout ___ parts of the exam

all

slit beam of light allows for ___________ imaging of layered tissues

cross section

purpose of slit lamp

1. routine ocular health assessment

2. contact lens evals

3. problem oriented, emergency care

4. used in combo w ophthalmic lenses for more advanced procedures

   1. gonio

   2. foreign body removal

   3. epilation

   4. fundoscopic exam

5. goldmann tonometry

whats different between Haag Style and Zeiss Style

1. haag - newer

   1. lighthouse positioned above oculars

2. zeiss - older

   1. lighthouse positioned belowt he microscope

microscope =

oculars

what are the haag style slit lamps in cs lab

1. topcon

2. haag streit - no built in yellow retina filter

3. marco

teaching tube shares a view w

the ocular it is mounted on

handheld portable slit lamps

1. heine

2. haag streit

3. keeler

4. reichert

anatomy of a slit lamp

1. illumination system - lighthouse

   1. where we make adjustment to light source

2. magnification - oculars

   1. change mag

   2. adjust to PD

   3. adjust ocular focus

3. mechanical base/joystick

   1. moves it

   2. changes focus in to thigns deeper in eye or more external

illumination system schematic

1. light source

2. stenopaic slit

   1. changes height or width and orientation angle

3. condensing lens

4. rotating mirror

illumination system lighthouse

1. variable apertures, change slit height

2. changes beam width (thickness)

3. can apply brightness diffuser and or filters

4. change orientation of slit beam from vertical to horizontal etc

parts

whats the first stop over after you get past max height

cobalt blue filter

what filters are there

1. open (full intensity)

2. neutral density (gray) filter

3. red free filter

4. optional yellow filter

5. cobalt blue

cobalt blue filter

1. excites fluorescein

2. in the top scrolling mm ruler

what can enance the green flow you see w a cobalt blue filter

handheld yellow Wratten filter

• good for contact lens evals

red free (green filter)

1. causes blood vessels to appear black

2. helps localize pigmented lesions in the fundus to either choroid or RPE

   1. RPE lesions REMAIN in your view

   2. choriodal nevus will leave us

3. improved contrast when looking at retina layers

   1. retina nerve fiber dropout (loss) appears as a black wedge inserting into the optic disc

external diffusor attachment

good for taking low mag photos showing natural colors

• all structures relatively clear and in focus

what do we ensure w the red arrow thing

1. click stop has to be in tight = in click vs out of click

2. keeps oculars focused at the same point the light is focusing

magnification system , microscope

1. focus one ocular at a time

2. dial in the max amount of plus then dial in minus until image is first clear

focusing oculars

1. insert focusing rods

2. adjust PD

   1. put them apart then together until you see one single image

3. focus one image at a time

4. make sure focusing rod is perpendicular

5. SLOWLY REDUCE PLUS
   UNTIL BAR IS FIRST CLEAR

6. if dr is fully corrected then each ocular should be close to 0

high mag =

less depth of focus

less field of view

1. more difficule to maintain sharp focus

mechanical base/joystick

1. scroll to move microscope up and down

2. move left to right to scan across

3. move forward and back to adjust plane of focus

4. base mounted rheostat for light intensity

   1. leave at half

safety for slit amp

1. always lock the slit lamp

2. be careful w tonometry apparatus

3. never leave the tonometry tip in front of the pt

how do you position a heavy or large chested individual

1. sit further forward in exam chair

2. lower the slit lamp table allowing for them to lean forward into chin rest

how do you position long leg pt (daddy long legs if you will)

remove footrest

allow them to put feet on floor

how do you position wheelchair person

1. entire chair can be pushed back so wheel chair can go where it was

how do you position kids

may need to stand on footrest

sit on knees in chair

sit on parents lap

use handheld slit lamp

operating the slit lamp

1. two hands

2. one on base or joystick

   1. base = big movements

   2. joystick = fine movements

3. other hand light houes - adjusting beam angle and beam width

when assessing temporal aspect of eye lighthouse is

temporal

beam angle

1. angle created between microscope arm and lighthoues

2. should be at least 30-50 degrees for most anterior structures

3. necessary for dept localization w layered tissue

corneal cross section - which is good and which is bad

adequate = 30-50 degrees

direct illumination

1. light is directed at and focused on the tissue to be examined

techniques of direct

1. diffuse illumination - broad beam

2. focal illuminatino

   1. optic section

   2. parallelepiped

   3. conical beam

   4. specular reflection

indirect illuminatino

1. light is directed to a secondary surface then reflected onto the tissue to be examined

indirect illuminatino techniques

1. proximal

2. retroilluminatino

3. sclerotic scatter

diffuse - broad beam

1. see large amount of area at once

2. beam be 3-4 mm wide

3. max beam height

4. beam angle 30-5- deg

5. low mag (10x)

6. moderate brightness intensity

7. lids, lashes, meibomian glands, conj, sclera, iris

optic section

1. thinnest brightest beam

2. max height

3. beam angle 30-60 deg

4. low to moderade mag (10-16x)

5. max brightness

6. provides max structural detail

7. most acturate detail

8. more layers tan parallelpiped

9. cornea

   1. should see a glistening of regular collagen lamellae of stroma

10. lens

11. good for localizing depth of things

    1. foreign body

    2. scars

    3. ulcers

    4. edema

parallelepiped

1. beam 1-2 mm wide

2. max beam height

3. beam angle 30-50 deg

4. low, moderate, or high mag (depends on tissue)

5. moderate brightness - bc beam is thicker

6. fewer layers than optic section

7. starting point for sclerotic scatter and specular reflection

8. cornea and lens

parallelelpiped benefit

1. enhanced surface detail than optic section

2. front half is epithelium second part is stroma and third part is endo

whats thsi

focus parallelepiped

look at center of beam

whats this

in focus optic section

whats this

neither

increase veam thickness until theres a white line

optic sectino for lens

1. optic section focused on cornea first

2. then push into pupil along the angle of the beam of light - not straight in or out

3. may need to dec beam angle to fit the posterior capsule into pupil margin

name

anterior lens

white black white

• ant lens capsule

• subcapsular space

• beginning of cortex

name

posterior inverted Y suture

theres also a really hard to see anterior y suture

name

posterior lens capsule part that is furthest right

parallelepiped - ascension phenomenon of the anterior vitreous

1. visualize movement of the anterior vitreous

2. dilated pupil

3. parallelpiped depper than posterior lens capsule

4. instruct pt to look up and then straight ahead

5. observe vitreous fibers floating down

conical beam

1. height small as possible = 0.2 or 1 mm circle

2. beam angle 40-69

3. moderate or high mag (16 25 40)

4. max brightness

5. anterior chamber cells and flare

specular reflection

1. monocular phenomenom

2. parallel piped beam to start

3. full height

4. wide beam angle

5. mod or high mag

6. moderate brightness

7. corneal endothelium , anterior and posterior lens capsules

specular reflection of corneal endo

1. monocular

2. PPD

3. bring ep of parallelpiped over to purkinje reflection/light box and look to see orange peel texture, structural detail of endothelium

4. provides textural surface detail under high mag

specular reflection of anterior and posterior lens capsule

1. monocular

2. PPD

3. full beam height

4. reduced beam angle

5. moderate mag

6. mod brightness

7. provides textual surface detail

proximal indirect illumination

1. light from illumination system is focused immediately adjacent tot he structure to be examined

2. good for corneal nerves, corneal neovascularization

3. PPD to start

4. full beam height

5. wide beam angle

6. mod bright

7. moderate mag

8. focus light at limbus and can see corneal nerves stretching into cornea

retroilluminatino from iris

1. PPD

2. full height

3. wide angle

4. mod bright

5. mod mag

6. light focused on cornes and lands on iris directly psoterior to it

7. light reflecting off the iris illuminates subtle corneal abnormalities

8. used when direct illuminatino would cause bleaching of image details

9. good for corneal neovascularization and keratic precipitates

retroilluminatino from fundus

1. monocular

2. PPD

3. focus on tissue to be examined - know where you are focused first

4. reduce beam angle to see red glow

5. cornea, lens, iris

sclerotic scatter

1. ppd

2. viewed from outside the slit lamp

3. wide angle - at least 60 deg

4. light will undergo total internal reflection

5. any corneal opactity will scatter light

6. shows cornea (abrasions, scars, FB, keratic precipitates)