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

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Presentation on theme: "ED Slit-Lamp Examination Andrew Shannon, MD MPH Department of Emergency Medicine Jacobi Medical Center."— Presentation transcript:

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

2 Why bother? ED Ophthalmology goals: –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 youre doing –provides superior magnification & stabilizes pts head for removal of corneal FB –tangential illumination aids in dx of uveitis/iritis cells and flare –billing? Eye exam interactive tutorial at –http://www.kellogg.umich.edu/theeyeshaveit/index.html

3 The Slit Lamp Low- to medium-powered binocular horizontally mounted microscope 1)Magnification 2)Elevation 3)Joystick for R/L movement & to focus 4)Slit width &/or height 5)Slit centration or off- set 6)Slit height & Intensity

4 –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 (+) Seidels test: ruptured globeWelders keratitis-- diffuse punctate lesions of the cornea caused by UV radiation dendritic appearance of HSV keratitis linear corneal abrasion

6

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 beam height for tall, narrow vertical beam adjust width for narrow beam w/ good illumination

9 slit width adjustment

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

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 –Slit-arm pivots around microscope mount 45 0 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 ~ 60 0

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 90 0 will increase amnt of cross-section –4 layers of corneal section: tears (outer) epithelium (& Bowmans membrane) stroma: seen as central gray granular area endothelium (& Descemets membrane): fainter back line –lens: opacities scatter & reflect more light - appear white (or pigmented) against gray background

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

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

17 van Hericks Technique: to assess anterior chamber angle –low mag (6x or 10x) –set beam 60 0 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) cornea iris keratic precipitates cornea

19 cells & flare corneairis 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 Rust ring residual from metallic FB Hypopyon layering in AC

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, rce=search_result. Content accessed 9/23/08.


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