HS Clinical Primer - Haag-Streit USA

A Clinical Short PrimerSlit Lamp Imaging and DocumentationContentsSlit Lamp ImagingSlit Lamp Imaging 3Csaba L. Mártonyi, CRA, FOPS, underscores the value of slit lampimaging as a clinical and teaching tool.Slit Lamp Imaging: Getting the Best Picture 4Haag-Streit’s Steve Thomson reviews techniques for maximizing theimaging potential of your slit lamp.Stereo Photography 10Marshall E. Tyler, CRA, FOPS, presents the advantages of viewing theeye in three dimensions with a photo slit lamp biomicroscope.Trigger Happy with the IM 900 12Bill Harvey tries out the latest slit lamp imaging system from Haag-Streitwith its novel history trigger function.Multiple Foreign Body Injury 14Dr. Revathi Rajaraman, Professor of Ophthalmology and Haag-Streit’sSteve Thomson present the case of a quarryman with multiple foreignbodies embedded in his cornea.Haag-Streit History 15Haag-Streit USA3535 Kings Mills RoadMason, OH 45040-2303haag-streit-usa.com1-800-787-5426The opinions expressed in this supplement to Review of Ophthalmology do not necessarily reflect the views, or imply endorsement, of the editor or publisher.By Csaba L. MártonyiThe informative power of the recorded imagecannot be equaled by even the most ardentdescription. Unlike words, and their interpretation,the slit lamp image is a neutral constant; abenchmark reference frozen in time. It becomesthe quintessentially unbiased witness to the conditionat the moment of capture.As the slit lamp represents one of the singlemost important tools in eye care, images recordedof observed conditions become equallyvaluable. Their immediate utility is obvious as ameans of closely following the patient’s condition,or immediate transmittal for consultation.For teaching, the captured image is without peerin conveying subtle information in context.The ability to transmit images worldwideserves to enrich the study ofthe eye and the search for solutionsto its problems.Today’s slit lamp is derived of a hostof brilliant minds and boasts a richhistory of evolution now vergingon the century mark. It is a facileinstrument of great ability. On thisplatform, slit lamp imaging has alsoattained an unprecedented plateauof relative simplicity. With electronicimaging, slit lamp photography is nolonger the daunting task of a fewyears ago. Immediate review ofcaptured images prompt necessaryadjustments in exposure, compositionand content. The prospect offailure to record essential informationis no longer a concern following thepatient’s departure until the film isprocessed.Never have more reasons existedfor digital slit lamp imaging: Highresolutioncameras reproduce the fine detail seenduring an examination; Longitudinal studies aremuch easier to conduct; Identification andstorage of images are simple operations, andretrieval is nearly instantaneous over customizablenetworks; The ability to transmit imagesworldwide serves to enrich the study of the eyeand the search for solutions to its problems; Forcertain conditions, where progression or regressionis measured in small increments (Figures Aand B), slit lamp images make possible a definitivecomparison, contributing significantly to theenhancement of patient care.Csaba L. Mártonyi, CRA, FOPSEmeritus Associate Professor and FormerDirector of Ophthalmic PhotographyUniversity of Michigan Medical SchoolAnn Arbor, Michigan, USAFigure A – Trans-cornealforeign body track with focalposterior corneal edema.Figure B – Iris transilluminationdefects in pigment dispersionsyndrome.23

A Clinical Short PrimerSlit Lamp Imaging and DocumentationSlit Lamp Imaging:Getting the Best PictureBy Steve Thomson1 IntroductionFor almost 100 years the slit lamp has beenused clinically primarily as a device that allowsthe user to observe the transparent structuresof the eye. In addition it can provide a magnified,stereoscopic view of almost the entire eye. Therecording of the image observed through the slitlamp was first introduced over forty years ago butthese analogue photo slit lamps were usually thedomain of the professional ophthalmic photographer.The recent digital revolution has seen aswitch from conventional film to digital media andhas increased the availability and affordability ofslit lamp imaging.As a clinical instrument the slit lamp comprises abiomicroscope and slit illuminator. The biomicroscopeproduces a three-dimensional image of theeye and the view is aided generally by focusedlight from the illuminator column. The depth offield observed with the slit lamp is relatively smallthus requiring efficient optics that have the abilityto transmit low levels of light. In use, and tocompensate for this shallow plane of focus, userstend to scan the image where their own visualsystem compensates. Light efficient opticshelp to enhance this perception. Furtherenhancement is perceived due to stereopsis.When an image is acquired it isonly a brief moment of this examinationthat is captured in two dimensions. Thisis the main reason why slit lamp imagescan be disappointing when compared tothe slit lamp view. Learning to view the imagemonocularly prior to capture, through the ocularto which the camera is attached will help achievebetter focus and improved composition.If your images seem consistently out of focuscheck the focus by compensating your refractiveerror in the eyepiece lens. This ensures that theplane of focus of your retina is at the same levelas the camera sensor. This is best achieved byusing an eyepiece that contains a reticule but canalso be checked by using a focus check rod and avery narrow slit.One of the important factors that limit the qualityof images is the amount of light made availablefor the sensor to record. This is far more importantthan the number of individual pixels thatcomprise the image sensor (cf. Sensitivity vs.Resolution in next section).2 EquipmentFrom the outside, most slit lamps look similarwith the only apparent difference being perhapsthe upright illumination tower.Many of the more subtle differences are not visiblefrom the outside but can only be appreciatedwhen a greater understanding of the instrumentsis obtained.Light is the main factor in imaging and it standsto reason that a slit lamp that has wider, morelight efficient optics may be superior to a devicewith lower aperture optics. This is important as tocreate the captured image only aportion of the light energy reflectedfrom the eye is available to thecamera as this must be sharedwith the observer. Generally abeam splitter is used for this purposeand for most arrangementsa device that sends 70% of lightto the camera and 30% to theoperator is the best configuration.Ideally, a beam splitter that canbe switched in and out combinedwith an aperture control that canbe used to control depth of field and/or imageexposure provides best image capture controland quality.There are many complete slit lamp imagingsystems available and all can produce images ofreasonable quality.The latest cameras from Haag-Streit, namelythe IM 900 and CM 900, have a unique methodof controlling the exposure from a convenientremote. Furthermore on capturing an image theprevious 30 frames are also recorded and thereforeany micro-saccadic eye movements or blinksdo not affect the image and the perfect imagecan be captured each time. This feature is especiallyhelpful when imaging the retina or whenattempting higher magnification images.There are numerous cameras that can be fittedto most current slit lamps and generally they canSensitivity vs. ResolutionThe camera sensor plays an important role in theimage quality. In recent years great progress hasbeen made in terms of sensitivity and resolution.A common misconception is that the higher thenumber of pixels, the better the image outcome.This statement may hold some truth if we wereimaging low contrast, evenly illuminated subjectsin bright conditions using a relatively small aperturelens system. In reality when imaging the eyewe have the opposite situation and any digitalcamera will have problems deciding on the levelof exposure. Slit illumination produces a high contrastsubject that is partially illuminated and ourarea of interest can vary between dark or brightlyilluminated portions. Furthermore both patientbe a video source that isthen digitized via computeror more commonly now,digital video. Digital videocameras are cost effectiveas no expensive computerhardware is required, howeverall require some form ofdriver software and computerhardware.Camera IntegrationThe relatively low upfrontcost attracts many users to use point-and-shootconsumer cameras with differing levels of success,but choosing the correct camera can bedifficult and learning how to use it best on theslit lamp can be time consuming. The introductionof a third optical arrangement, the integratedcamera lens system, increases the difficulty ofgetting good, consistent results.Most affordable cameras cannot faithfully recordthe image we observe though the slit lamp asthere is a significant difference in the dynamics ofrecording the information. Clinically we can easilyvisualize detail in the bright slit and darker surroundingregions with the benefit of our complexvisual system.Camera sensors, however, do not yet have thesame ability to distinguish areas of wide luminancechange that we can observe.tolerance and international regulations limit thelevel of light that can be used. This means that acamera with increased sensitivity – an ability tomore efficiently record the light photons – is likelyto produce a better image than a camera that haslower sensitivity. The efficiency of the camerasensor is generally related to the individual pixelsize and therefore it is likely that if two sensors ofequal resolution (number of pixels) are compared,the sensor with the larger pixels will reproducethe subject more faithfully. In practice for slitlamp imaging, this means that unless an auxiliaryflash system is used, the best solution is a compromisebetween the individual pixel size and thetotal number of pixels on the sensor.4 5

A Clinical Short PrimerSlit Lamp Imaging and DocumentationFigure 1 Figure 1a Figure 2 Figure 2a Figure 3 Figure 3a Figure 4 Figure 4aBackground IlluminationThe dynamic range of some cameras is improving,but to help produce a more realistic lookingimage, and to provide some extra light energy tothe sensor, a background, or fill illumination lightsource can significantly improve image quality.Background illumination is generally delivered tothe eye as diffuse light from a small exit sourceto minimize reflections. This light is normallyvariable by means of an aperture control and thisvariation assists in creating the required balancebetween slit illumination and background detail.Creating the correct balance between the backgroundillumination and slit illumination is important.Too much background light saturates theslit image, whereas too little will improve the slitimage but the user may find it difficult to orientatein the otherwise dim image.3 Illumination Techniques1. Overview ImageThe overview image is generally used to set thescene. In normal practice several images maybe required to record faithfully the state of theeye and a simple, low magnification image canbe used to orientate the viewers of an imageseries. Fitting a diffuser to the slit illuminator andopening the slit to the widest beam achieve thediffuse illumination. This can be used in combinationwith the background illuminator to producean image that has balance and shows good detail.If the sole illuminator is used close to the opticalaxis, the image may lack detail as in this positionthe lighting will flatten some features in thesubject.Figures 1 and 1aPearlIf the angle between the illumination and slitlamp objective is increased to around 45 degrees,detail will be enhanced, however, one side of theimage will appear dark. Using a 2nd source at 90degrees to the primary light source will reducethis effect and improve the image.Using low magnification ensures that a gooddepth of field is achieved and that with some slitlamps cornea, iris and a portion of conjunctivaand sclera will appear in focus.2. Narrow Slit Image — Optical SectionNone of the structures in the eye are absolutelytransparent and it is this fact that allows us toview them with the slit lamp. A normal window,much like a cornea, looks clear in diffuse light.However, when a narrow beam of intense illuminationis introduced at a wide angle to theviewing angle then detail can be observed in theilluminated section. In slit lamp biomicroscopythis is often referred to as an optical section asin the cornea and lens it can look similar to a thinslice through the semi-transparent media.Creating an image of an optical section can bea challenge for some imaging systems. This isbecause only a relatively small amount of light energyis projected into the eye via the slit. The opticaleffect can only be observed if the slit width isless than 0.2mm and therefore either very largeamounts of energy such as a flash from a photoslit lamp or a highly sensitive camera sensor isrequired. The first step in creating this image istherefore to turn the flash or lamp energy up tomaximum and reducing the slit width to around0.2mm.In addition to the optical section the narrow slitcan also be used to measure the relative thicknessof the cornea, demonstrate anterior chamberdepth and define surface topography.Figures 2 and 2aPearlThe optical section cannot be observed unlessthe angle between the incident light and reflectedlight is large. In the cornea it is possibleto achieve an angle of 90 degrees at which thewhole corneal section will appear in focus. Themaximum angle in the lens is around 45 – 50degrees and this can be improved with patentdilation. The maximum detail will be visualizedwhen no fill light is used. However, in some situationsa small amount of diffuse light is required toorientate the viewer.If the slit lamp has an aperture control it is likelythat this will have to be at the widest setting foroptical section imaging. The magnification of theslit lamp should also be considered. With each increasein power, the depth of field decreases andthe effective aperture of the instrument increasesand limits the light further. If low light levels arecompromising the quality of the image then usinga lower magnification may help.3. Wide Slit Beam ImagingUsing a moderate slit width of between 1 – 2mmone can demonstrate separation between corneallayers and, much like a spot light, can be usedto highlight pathology. A wide beam of 4 – 8mmprojected tangentially across the eye can beextremely effective lighting for some very subtlepathology. The wide angle enhances surfacetexture and the relatively high light levels allowhigh magnification and reduced apertures in mostsystems.Figures 3 and 3aPearlGenerally in tangentially illuminated images no filllight is used, when a moderate slit width is useda small amount of fill can be used to help orientatethe image. Be aware that the larger patch oflight may introduce larger reflections or artifactsthat can be managed by altering the angle of thelight tower, microscope or even the eye.4. Indirect illuminationIndirect illumination can be used to enhancedetail in the semi transparent media of the eyesuch as the cornea. Very subtle details can bevisualized using light reflected from other surfaceswithin the eye, as it would otherwise besaturated by direct focal illumination.In normal use the slit and microscope have acommon point of focus. When attempting indirectillumination the slit is defocused from thispoint and directed towards the reflecting tissue.The degree of defocus and the background of thesubject can have a large effect on the image thatis produced.Figures 4 and 4aPearlMany corneal irregularities can be imaged byusing a technique of sclerotic scatter as a formof indirect illumination. When a 3 – 4 mm widebeam is fully decentered and directed towardsthe corneal limbus, the energy reflected from thesclera is returned into the cornea and by total internalreflection is distributed through the wholecornea.5. Retro-IlluminationRetro-illumination is a type of indirect lighting thatuses the retina to reflect the energy from theslit illuminator. Abnormalities in the media of theeye can then be observed as this reflected lightis either refracted or absorbed by the defect. Irisatrophy and similar defects can also be visualizedby retro-illumination.For retro-illumination of the lens and cornea thepupil should be dilated, as the light energy has to6 7

A Clinical Short PrimerSlit Lamp Imaging and DocumentationFigure 5 Figure 5a Figure 6 Figure 6a Figure 7 Figure 7aget in and out of the eye on a different path. Withmost systems a pupil diameter of at least 4mmwill be required but generally the wider the pupilthe better the image. The slit lamp should thenbe arranged so that the slit illumination and themicroscope objective to which the camera is attachedare aligned coaxially. The red reflex shouldbe visible but the corneal reflex will compromisethe view. Defocusing the slit to the edge of thepupil will move the central reflex and improve theimage. Small movements of the slit illuminatorcan be used to optimize the image brightnessand this is best observed monocularly. The threesteps to produce good retro images are (i) Setthe slit for coaxial illumination to visualize the redreflex (ii) defocus the slit to remove central reflex(iii) fine tune the slit (size, width, position) to obtaingood reflex with minimal artifact.Figures 5 and 5aPearlIdeally the size and shape of the slit should beadjusted so that the white reflex is minimized andthe red retro reflex is bright and even. In somepigmented eyes, through small pupils or wherea brighter retinal reflex is required, the patient’sfixation can be positioned slightly nasally. This willdirect the illumination towards the optic nervehead where the lamina cribrosa will significantlyintensify the reflected light.When attempting to retro illuminate the iris theslit need not be defocused as the pupil is usedfor the incident light. Care should be taken tomake the light patch slightly smaller than thepupil and thus avoid causing reflections from theiris that may in turn produce a reduction in imagecontrast. Again a 3-4mm pupil is required to getsufficient light into the eye and therefore a partiallydilated pupil will help.6. Fluorescence ImagingSodium Fluorescein has a number of uses inOphthalmology and it is frequently used with theaid of a slit lamp to visualize regions where thecorneal epithelium has become eroded or damaged.A further application of topically appliedfluorescein is to mix with the tear film to facilitatetonometry, assess the tear film break uptime, and improve the fitting of contact lenses.A small amount of sodium fluorescein is sufficientto temporarily stain damaged epithelialcells and deepithelialized regions of the cornealsurface. The dilute sodium fluorescein (orange)will give off energy at a higher wavelength (yellow– green) when stimulated by an exciter (blue)light source. Thus by using the cobalt blue filterbuilt into most slit lamps, the biomicroscope canbe used to observe the stained tissue. It is possibleto document the fluorescence stain but itshould be considered that the light levels are verylow and either flash or a high sensitivity camerasensor is required.The key to obtaining good quality fluoresceinimages is to use only a small amount of dye andthen, after a few blinks by the patient, rinse theexcess from their eye using a sterile solution.Imaging performed quickly after this stage willshow good detail without being over saturated byfluorescein pooled in the tears.Figures 6 and 6aPearlThe slit lamp magnification should be set to 16xmagnification with the slit illumination fully open.Using cobalt blue (exciter) filter in place andinstrument viewing bulb full intensity will ensurethat maximum light is available. Even illuminationis desirable and therefore the angle of theillumination should be close to the microscope.Disturbing reflexes can be managed by slightpositional changes to this arrangement. Thefluorescent stain can be observed against theblue background of the cobalt blue light and thisis often sufficient to provide some backgroundor orientation information. If more detail of thestained region is required a yellow – green barrierfilter can be used. This filter blocks the blueexcitation light and therefore increases contrastin the areas stained with fluorescein but it willalso further reduce the light level. A matchedfilter from the slit lamp manufacturer is best but aKodak Wratten No. 12 is a good substitute.7. Retinal ImagingBinocular indirect ophthalmoscopy (BIO) is a routinepart of the clinical examination where the slitlamp is used with a hand held condensing lens toprovide a stereoscopic view of the fundus. Imagingusing a lens designed for BIO is a relativelyeasy task providing there is knowledge of theslit lamp and an understanding of the principalsinvolved. It should also be remembered that thisexamination is dynamic and that the image capturedcan only represent a small portion of thisassessment.When held at its correct working distance fromthe eye, the condensing lens produces a magnifiedimage of the fundus approximately the samedistance in front of the lens. The field size andmagnification are dictated by the design of thelens and the image magnification can be furtheradjusted by the slit lamp magnification control.Figures 7 and 7aPearlSome clinical examinations can be carried out onundilated eyes but imaging through a small pupilis extremely difficult. In addition, observing theimage binocularly can mask some reflection andartifacts and therefore it is recommended that imagingshould be attempted monocularly throughdilated pupils whenever possible.The use of a lens that is held in contact with theeye such as the Goldmann 3–mirror can improveimage quality as reflexes can be reduced furtherand stability is increased. The central opticalzone of the 3–mirror is used for visualization ofthe posterior pole and peripheral retinal can beobserved via either of the two largest mirrors.Adversely the cornea requires to be anaesthetizedand a coupling gel is required when a contact glassis used.4 Preparing Images for DocumentationRoutine documentation as part of the clinicalexam is the main use for slit lamp images but andincreasingly slit lamp images are being used forpublication and teaching purposes.Generally routine clinical images need no furthermanipulation but those images intended for wideraudiences could be improved by using image-editingsoftware.Clinicians are obliged to treat medical images inthe same confidential manner that they would withpatient medical records. Furthermore significantlyaltering clinical images using digital manipulation isnot recommended. Consequently when preparingimages for other uses it is suggested that a copyof the original image is used and that the originalremain unaltered.SummaryProducing high quality slit lamp images can beextremely rewarding. By investing some time inpractice almost everyone can improve their technique.Attempt to appreciate the different typesof illumination, and observe the very subtle patternsproduced by small changes in the illuminationtechnique. Attempt to remember the differencesbetween the clinical exam and imaging andprocedure.Finally, learning to understand the abilities or limitationof your slit lamp will tremendously improveoutcome in image and diagnostic quality.For more information, please go to http://www.haag-streit-usa.com/prod/Slit-Lamps/BX900-Photoguide2.pdfSteve Thomson is an Ophthalmic Photographer and anemployee of Haag-Streit AG, Switzerland.8 9

A Clinical Short PrimerSlit Lamp Imaging and DocumentationDigital Stereo Photography with thePhoto Slit Lamp BiomicroscopeBy Marshall E. TylerThe modern slit lamp biomicroscope provides amagnified, three dimensional view of the eye.The ophthalmic photographer’s challenge is torecord this three dimensionalinformation.The slit lamp examinationproduces a single mentalcomposite image that includesheight, width, and, of crucialimportance – depth. The thirddimension is essential to understandingcertain structuralrelationships, without which,the examination would beconsiderably less informative.Similarly, stereo slit lamp photographyis far more effectivein describing certain conditionsand relationships than thesingle, two dimensional image.Stereo slit lamp photographyproduces a permanent recordthat is the closest possible approximationto the view seenby the clinical examiner. Foreducating students, the stereophotograph can make the differencebetween just seeingthe pathology and truly understandingthe pathology.Not surprisingly, the significantadvantages of stereo photographyare commensurate withthe disadvantages of instrumentcomplexity and cost, aswell as the effort required toview the results.Stereo Photo Slit Lamp BiomicroscopeStereo slit lamp biomicrography requires dedicatedinstrumentation. Unlike ocular fundus photography,where stereo pairs are usually obtained ina sequential manner, the stereo photo slit lampmust capture both images simultaneously. Inadvertentmovement of the subject eye amplifiedby high magnification (and other factors) essentiallyeliminates the option of sequential recordingof stereo images at the slit lamp.Stereo imaging isaccomplished witheither a two camerasystem (see the fulltext for this system) ora system based on asingle camera using asplit-frame system. Fullframe systems producelarger individual imagesat higher resolution, aseach frame utilizes thefull resolving capabilityof the film or digitalsensor used. Split-framesystems (eg: Haag-Streit BX 900 ® ) recordboth left and right sidesof the stereo pair on asingle frame of film ordigital sensor. Theseimages contain approximatelyone halfthe resolution of fullframe images. A splitframesystem, however,has the advantages ofgreater simplicity ininstrumentation and apermanently fixed, nonvariablejuxtaposition ofthe left and right images.Photographing bothimages simultaneously ensures that there is nosubject movement between the stereo images.Masking of the fuzzy image edges encouragesquick alignment of the viewer’s eyes for full andaccurate stereopsis.Haag-Streit split-frame stereo photo adapter onBX 900.The Haag-Streit BX 900 ® is the only digital stereophoto slit lamp biomicroscope in current produc-tion. It is an integrated, fully capable photographicinstrument equipped with co-axial electronic flashfor the slit illuminator and the fill light. Imagesare recorded as split-frame stereo pairs on the“full frame” (23.9 x 35.8mm) sensor of the digitalcamera. The camera is mounted on a mirrorhousing providing sequential, 100% illuminationintensity for both examination and simultaneousstereo photography.Viewing Stereo ImagesStereo photographs demonstrate how depthenhances the understanding of the pathology.Split-frame stereo images store both the left andright images in a single image file. The left imagemust be viewed with the left eye and the rightimage with the right eye. Side-by-side viewing ofstereo images is a commonly accepted format fordisplaying stereo images in journal publications.Images may either be printed (or displayed on acomputer screen) about 2” wide for each of theimages in the stereo pair for direct viewing with+5D lenses.For more clarity a Brewster viewer may be usedto view larger stereo image pairs. Behind each ofits two plus lenses, two mirrors create the effectof widening the viewer’s inter-pupillary distanceto match the center-points of the two imagescomprising the stereo pair – usually with each ofthe two images is printed about 4” wide.Stereo images with the subject in full color, orB&W, may be turned into chromatic anaglyphsand viewed with red-cyan glasses.The Future of Stereo Slit lamp ImagingThe value of the three dimensional informationderived from the two images of a stereo pair istruly greater than the sum of its parts. Its utilityto the clinician should not be underestimated. Intelemedicine, stereo images increase the diagnosticcapabilities of the consulting physician.Simultaneous stereo images, taken with a fixedand reproducible stereo base, permit high-qualitycomputer analysis. Considering the importanceStereo split frame image before masking to hidefuzzy image edges which make stereo imageviewing easier.of this modality, it is essential for the ophthalmicphotographer to master the skills required toproduce consistently high quality stereo images.A complete understanding of these theories andpractices will ensure the optimum imaging supportin the care of the patient.By Marshall E. Tyler, CRA, FOPSResourcesOphthalmic Photography books:Twin Chimney Publishingwww.TwinChimney.comReferencesC. Martonyi, et.al., Slit Lamp: Examination and Photography,Revised and Expanded Third Edition, ©2007www.TwinChimney.comSaine PJ, Tyler ME. Ophthalmic Photography: Fundusphotography, Angiography, and Electronic Imaging.Second Edition. Butterworth Heinemann ©2002.Tyler ME, Saine PJ, Bennett TJ. Practical RetinalPhotography and Digital Imaging Techniques. TwinChimney Publishing ©2007.Braley A, Watzke Rvvv, Allen L, Frazier O. StereoscopicAtlas of Slit-Lamp Biomicroscopy, vol 1, C V Mosby, StLouis, 1970Tele-Ophthalmology. Edited by Kanagasingam Yogesan,ISBN 3-5402-4337-2, ©2006 SpringerMerin L. Construction and use of stereo viewers. JOphthal Photog 1981;4:39.Bennett TJ, Stereo Anaglyph Preparation for Power-Point, J Ophth Photog; Spring/2005 Vol 27:110 11

A Clinical Short PrimerSlit Lamp Imaging and DocumentationTrigger HappyBy Bill HarveyBill Harvey tries out the latest slit-lamp imagingsystem from Haag-Streit and is impressed by itsnovel history trigger function.‘Just stare straight ahead. Hold it! Hold it! And…’click! The number of times the system capturesa blink or a moving eye can be quite frustrating.There is often a delay between pressing thebutton or foot pedal and the capture of the actualFigure 2Figure 1image, meaning several attempts are usuallyneeded before the best image is obtained and selectedfor storage, analysis, transfer or whateverelse is required. This takes up valuable time ofboth the practitioner and the patient. It also leadsto a rapid build-up of images to be sorted throughon the hard drive. However, a new imagingsystem includes features that make this athing of the past.The IM 900The new IM 900 is an integrated camerasystem (Figure 1) with a 2 megapixel cameraintegrated into the microscope of theslit lamp. There is also a variable stop adjustment,allowing a reduced stop for highermagnification images when a bigger depthof focus is required. Image capture is eithervia a foot pedal or – as in the case of thesystem trialled recently at City University –a large button at the base of the unit to thefront of the joystick. On either side of thelarger capture button, which I found easierto use than a foot pedal, are two smallerbuttons. During capture mode, these maybe toggled to change the exposure of theimage. Combined with a variable brightnessbacklighter, the rheostat of the slit lamp itself andthe controlled aperture setting for changing depthof focus, this represents the most adaptableimaging setup I have encountered. And with justa few minutes of practice even some of the moredifficult images become easily attainable.Figure 3Figure 4Figure 5These include a good optic section of the cornea,either with or without backlighter. As this viewrequires the thinnest of beams, very often thelight levels are too low for capture until the beamis widened – but then the detail of the section islost. Not so with this system.Similarly, a good section of the lens is possibleand even the capture of the retrolental spaceand anterior vitreous, as if aiming to view tobaccodust. This is notoriously difficult to achievebecause of the reduced light levels reflectingfrom behind the iris. The image shown has beenenhanced by increasing the gamma setting aftercapture and the anterior vitreous face is justvisible. Figure 2 shows another often difficultcapture, the endothelium. By adjustment of theincident light it is possible to see some cellularshape detail. Figures 2 to 7 show a variety of imagestaken during our session.For sheer use and adaptability I have to say thatthis represents the best slit-lamp image capturesystem I have used to date.I was also able to try image capture when usinga fundus viewing lens. The patient shown hassignificant myopic degeneration and an area ofchorioretinal scarring may be seen on screen.This was especially useful, not only to show tothe patient, but also to show to the students tocheck that what they had seen with their examinationtallied.History triggerOne push of the button or foot pedal captures theimage instantaneously, something that Haag-Figure 6Streit calls ‘freeze technology’. However, for allthose instants where the final image is not theprecise one desired, the system includes a usefulfeature. The previous seconds up to the pointof capture are also stored. If the image seen onscreen is not adequate or as good as wished,the two buttons at the side of the capture buttonallow the user to scroll back through precedingpresentations, each click showing the imageseveral milliseconds before.For the blinking eye it was possible to click backthree times until a view was selected that wassuitable and then a second click of the capturebutton stored that as the definitive image.Adaptable and easyFigure 7For sheer ease of use and adaptability I have tosay that this represents the best slit lamp imagecapture system I have used to date. The historytrigger function is a great help and the quality ofthe images produced are excellent.Bill Harvey is a Vision Science Lecturer at City University,London and is the clinical editor of OpticianMagazine.Reprinted with permission of Optician and author, BillHarvey. The original article appeared in Optician April13, 2007.12 13

A Clinical Short PrimerSlit Lamp Imaging and DocumentationPhoto Case Study —Multiple Foreign Body InjuryHaag-Streit:150 Years of Precision Instrumentation1930s: Cooperation with Dr. HansGoldmann. During the early 1930s the companybegan a long-lasting relationship with Dr. HansGoldmann that led to the development of themodern slit lamp models 320 and 360.Figure 1Figure 2Figure 3Figure 4In 1945: the Goldmann Perimeter was introducedto the market and with the end of the war, thedemand for ophthalmic diagnostic equipmentexploded.By Revathi Rajaramanand Steve ThomsonMr. R, a 39-year-old male, presented on June 3,2006 with a red, painful Left eye. He reported aforeign body sensation following an accident atwork. He is employed as a quarryman and hadbeen blasting and cutting rocks. No eye protectionwas used. He had a past history of similarinjury in the Right eye under identical circumstanceseight years previously.On examination the Right eye achieved a bestcorrectedvisual acuity of 6/9 and the Left eye of6/36. On slit lamp examination multiple foreignbodies were observed embedded in the cornealstromal layer and, in the lens, an old posteriorsynechiea in an otherwise quite right eye. TheLeft eye displayed multiple conjunctival andcorneal foreign bodies, cells in the aqueous andmultiple small tears in the iris sphincter alongwith a mid-dilated pupil. The lens was clear in theLeft eye and in both eyes posterior segmentswere normal in direct visualization and by ultrasonicB-Scan.Mr. R was treated with topical Moxifloxacin andPrednisolone Acetate eye drops six-hourly andHomatropin eye drops eight-hourly, tapered overfour weeks.On review after five weeks the visual acuity inthe Left eye improved to 6/12 and the eye becamequieter.The images were taken June 3, 2006, one dayafter injury to the Left eye and eight years afterinjury to the Right. Diffuse overview imagesclearly show multiple intra corneal foreign bodiesin both eyes. The slit image (Figure 1) of the Lefteye demonstrates several corneal foreign bodiesand a few anterior chamber flare cells. Usinga slightly wider slit and, focusing the slit lamp inthe anterior chamber, (Figure 2) better illustratesthe volume of inflammatory cells present.Retro illumination of the lens in the Right eye(Figure 3) demonstrates the embedded stonefragments and an irido-capsular adhesion. A tearto the iris sphincter is also visible inferiorly. In theLeft eye (Figure 4) the cornea is retro illuminatedrevealing that many of the fragments are semitransparent.The pupil margin, delineated by theretro illumination, shows evidence that the irishas also suffered multiple tears.Sclerotic scatter illuminates the cornea internallyand shows that the cornea has suffered traumafrom several hundred stone fragments.The images were captured using a Haag-Streit BXslit lamp fitted with a Canon EOS 20D camera.Dr. Revathi Rajaraman - Cornea and Refractive SurgeryServices, Aravind Eye Hospital and Post Graduate Instituteof Ophthalmology, Coimbatore, Tamil Nadu, India.Steve Thomson is an Ophthalmic Photographer and anemployee of Haag-Streit AG, Switzerland.Reprinted with permission of The Journal ofOphthalmic Photography and co-authors Dr.Rajaraman and Steve Thomson. The original articleappeared in Volume 29:1:34-35 Spring 2007.Bern, Switzerland 1858: Training comradesFriedrich Hermann and Hermann Studer opened asmall mechanic workshop in the old part of Bern.In the early years, cooperation with meteorologistand renowned physicist, Professor Heinrich Wild,led to the development of a variety of precisionmeasuring instruments.The young company earned a reputation for combiningthe finest precision mechanics with excellentoptics. Word of their outstanding achievementsspread throughout the world of science.1876: Instruments for OphthalmologyAfter the death of H. Studer in 1863 and FriedrichHermann’s departure in 1881, the small companyheaded by J.H. Pfister, encountered difficult yearsuntil Alfred Streit joined the company.Streit introduced new manufacturing techniques,moved the company to a new facility and developednew products that helped the companyregain lost ground. Around the turn of the centurythe well-expanded product range included ophthalmometers,perimeters, coordinatographs andmeteorological measuring instruments. Inaddition, initiated by Prof. Siegrist of the UniversityEye clinic in Bern, the company developed thefirst ophthalmoscopy and investigation lamp.1925: Alfred Streit’s son-in-law, WilhelmHaag, stepped into the company and renamed itHaag-Streit.1950: Haag-Streit was incorporated. In subsequentyears the product range expanded toinclude the Goldmann-Weekers adaptometer andthe Goldmann applanation tonometer. In 1958 thefirst Slit Lamp 900 was introduced to the market.Fueled by the popularity of the slit lamp and thetonometer, Haag-Streit expanded its distributionnetwork to over 40 countries.1969: Haag-Streit introduced the famous 3-Djoystick. Soon thereafter the company’s involvementin consulting and sales of refraction units,led to today’s complete examination and deliverysystems. The 900 BM and CN, introduced in1978, were the predecessors of today’s BQ 900and finally BX 900 slit lamp systems.1988: With CEO Walter Inäbnit, Haag-Streit AGexpanded its global presence.21st Century: Today, headquartered in Koeniz,Switzerland, Haag-Streit operates a group of 18companies and employs 880 people. The groupmaintains operationsin Switzerland,France,Germany, Austria,United Kingdom,and the UnitedStates. Through aworldwide networkof sales organizations,it offers adiverse portfolioof premium products and services for healthcareprofessionals in eye care, neurology, otolaryngology,pneumology, and microsurgery.14 15