1. ED Slit-Lamp Examination
Andrew Shannon, MD MPH
Department of Emergency Medicine
Jacobi Medical Center

2. Why bother? ED Ophthalmology goals: The Slit-lamp Exam:
R/O or R/I ruptured globe, retained foreign body, corneal abrasion, diagnose HSV corneal ulcer
The Slit-lamp Exam:
makes you look like you know what you’re doing
provides superior magnification & stabilizes pt’s head for removal of corneal FB
tangential illumination aids in dx of uveitis/iritis
“cells and flare”
billing?
Eye exam interactive tutorial at

3. The Slit Lamp
Low- to medium-powered binocular horizontally mounted microscope
Magnification
Elevation
Joystick for R/L movement & to focus
Slit width &/or height
Slit centration or off-set
Slit height & Intensity

4. Light-source intensity
Slit width
Wide- survey globe/cornea
Narrow- depth, width & position of small abnormalities
beam as wide as cornea is thick
forms a parallelepiped volume: a box of illuminated tissue is seen
Thin (slit)- narrowest beam forms an optical section
so thin it's just discernible
valuating small changes in clarity & pinpointing depth of pathology
Light-source intensity
Medium to high: most purposes
High: optical section
Filters
neutral, cobalt blue (for fluorescein), red-free
Magnification
low power (~10x) is used for survey
medium to high (16-40x) for optic section & parallelepiped
high (40x) for specular reflection
normally, light is focused at same point as microscope (“parfocal”)

5. (+) Seidel’s test: ruptured globe
“Welder’s keratitis”-- diffuse punctate lesions of the cornea caused by UV radiation
(+) Seidel’s test: ruptured globe
dendritic appearance of HSV keratitis
linear corneal abrasion

7. Slit lamp technique Start w/ 10x eyepieces & lower powered objective
(“1x” or “12” on JMC scopes)
Use lowest voltage setting on transformer
ensure open aperture
Select the longest slit length
Adjust chin rest
Pt's eyes approx level w/ marker on head rest
Slit arm in line w/ microscope
Lamp height w/ slit beam centered vertically on Pt's medial canthus
Focus by moving joystick

8. locking nut: loose for free movement Ocular focus to 0
adjust width for narrow beam w/ good illumination
adjust beam height for tall, narrow vertical beam

9. slit width adjustment

10. magnification adjustment
beam height
slit-width adjustment
filter rheostat
slit-arm locking knob
focus & lamp height
locking nut (horizontal)
intensity
locking bar (vertical)

11. Magnification adjustment can be found in various locations, including btwn the eyepieces
The filter rheostat can be used to decrease Pt discomfort under exam w/ the lamp (neutral density filter)

12. Position of the Light Methods of viewing
Slit-arm pivots 1800 around microscope mount
450 angle, directed temporal to nasal is standard
In-line w/ scope for initial survey of lids, lashes, lacrimals, conjunctiva and sclera
Methods of viewing
Direct illumination: beam directly pointed at specimen
gross pathology
Retro-illumination: beam de-centered to illuminate behind area of interest while it is still in focus
may bring out subtle optical changes
thin vascularization, small incisions, endothelial abnormalities
Sclerotic scatter: light spreads by total internal reflection
uses a beam ~1mm wide, ½ height of cornea & pointed at limbus
subtle abnormalities as light through the cornea scatters off of any pathology

13. Forehead should be in contact w/ restraint
Eyeline should be at level of indicator
Angle of slit-arm ~ 600

14. Direct/focal illumination
Most common; focused slit; magnification 10x40x
wide beam for surface study; narrow beam for sections
Broad beam (parallelepiped) section of cornea
2mm slit: corneal surface & stroma
to ascertain depth (FB, abrasion)
Narrow beam (optic section): easier to determine precise depth
resolution improved by reducing slit width; clarity improved w/ increasing mag
angle btwn slit-arm & scope ~
increasing angle up to 900 will increase amnt of cross-section
4 layers of corneal section:
tears (outer)
epithelium (& Bowman’s membrane)
stroma: seen as central gray granular area
endothelium (& Descemet’s membrane): fainter back line
lens:
opacities scatter & reflect more light - appear white (or pigmented) against gray background

15. iris on tangential illumination
SLE w/ wide slit on a post-op IOL Pt dx’d w/ Propionobacterium acnes endophthalmitis
light source
outer epithelium of cornea

16. SLE thru dilated pupil:
anterior chamber (AC)
crystalline lens
cornea
SLE lateral view showing intra-corneal lens anterior to native crystalline lens
light source

17. van Herick’s Technique: to assess anterior chamber angle
low mag (6x or 10x)
set beam 600 to side of scope
place narrow slit as close to limbus as possible & perpendicular to the cornea
compare width of cornea seen by optical section w/ the dark section seen btwn front surface of iris & back of cornea
GRADE 4: ratio of aqueous to cornea is 1:1 - open angle
GRADE 3: ratio of aqueous to cornea is 1:2 - open angle
GRADE 2: ratio of aqueous to cornea is 1:4 - narrow angle
GRADE 1: ratio is < 1:4 - dangerously narrow angle
Conical beam: used to detect aqueous flare
inflammatory cells in AC (eg acute anterior uveitis)
room illumination must be completely dark
can only be seen using conical beam of light
set slit-arm angle btwn
focus onto front surface of cornea w/ high magnification
W/ pupil as dark background, flare may be seen btwn focused beam of light on cornea & the out-of-focus beam on lens
in normal eye this space will be clear

18. “flare” in anterior chamber (AC)
keratic precipitates
iris
                                                                                                                        
cornea
cornea
“flare” in anterior chamber (AC)

19. iris
cells & flare
cornea
light source
cornea
iris
no cells or flare

20. Indirect Illumination
Evaluate tissue outside directly illuminated area
reduced glare; easier to view opacities, corneal nerves & limbal vessels
focus on feature directly & then swing lamp to one side
Retro-illumination (rarely useful in ED!)
light reflected off deeper structures (iris or retina) w/ microscope focused on ant. structures
study cornea in light reflected from iris; lens in light reflected from retina
light-opaque features are dark agnst light backgrnd (scars, pigment, vessels containing blood)
light-scattering features appear lighter than background (e.g. corneal precipitates)
useful for examining size / density of opacities (not location)
1) use a parallelepiped beam, focus on retina
2) direct retro-illumination: observed corneal feature viewed in direct pathway of reflected light
angle btwn microscope & illuminating arm ~ 60°
3) indirect retro-illumination: angle is greatly reduced /increased so feature on cornea is viewed against dark bckgrnd

21. keratic precipitates (direct & retro-illumination )

22. Hypopyon layering in AC
“Rust ring” residual from metallic FB

23. References:
My Hanh Nguyen. Ophthalmology Grand Rounds. Tufts Unviersity. Content accessed 9/23/08.
Introduction to Slit Lamp Technique. CYBER-SIGHT: Copyright © 2003 Project ORBIS International Inc. Content accessed 9/23/08.
G Papaliodis. Propionibacterium acnes Endophthalmitis. Ocular Immunology and Uveitis Foundation. Massachusetts Eeye Research and Surgery Institution. Copyright © C. Stephen Foster M.D. Content accessed 9/23/08.
Vance Thompson. Postoperative Care for Phakic Intraocular Lens Implants. In: Phakic Intraocular Lenses: Principles and Practice by Hardten, Lindstrom, and Davis. Slack, Inc. Content accessed 9/23/08.
Jared Schultz. One intracorneal segment treats keratoconus better than two. Copyright 2008 SLACK Inc., Content accessed 9/23/08.
Craig Blackwell. Narrated Eye Exam: Copyright Content accessed 9/23/08.
Patient Glossary. Ocular Immunology and Uveitis Foundation. Massachusetts Eeye Research and Surgery Institution. Copyright © C. Stephen Foster M.D. Content accessed 9/23/08.
JG O'Shea, DA Infeld, RB Harvey. Uveitis- a photoessay. Content accessed on 9/23/08.
Second Year 99/00: Clinical Optometry 3. Slit lamp examination: Practical. Content accessed 9/23/08.
KJ Knoop. Slit-lamp exam. Uptodate.com. Last updated: February 12, Content accessed 9/23/08.