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ED Slit-Lamp Examination

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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. Last updated: February 12, Content accessed 9/23/08.

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