Don Wong, RBPFundus photography and fluorescein angiography 13

tutorial

Fundus photography and fluorescein angiography

Don Wong, RBPDepartment of Ophthalmology

Cabrini Health. Care CenterNew York, New York

About the author—Don Wong, B.A., RBP, isthe chief ophthalmic photographer and man-ager of the Department of Ophthalmology,Cabrini Health Care Center, 227 East 19thStreet, New York, New York 10003.

14 Journal of Ophthalmic Photography Vol. 2, No. 1 August 1979

Fundus photography and fluorescein angiography

CONTENTS

page

I. Photography in ophthalmology and the apparatus ............................... 15

II. Anatomy ............................................................................................ 26

III. The photographic procedure .............................................................. 32

IV. Photography of the external eye; photographic artifacts;

the patient ........................................................................................ 37

V. Fluorescein angiography ..................................................................... 46

Reprinted with permission from the Journal of the Biological Photographic Association: 44, 105-115, 148-153, and 45 26-30 69-77, and 104-114.© 1976, 1977, Biological Photographic Association, Inc.

Don Wong, REP Fundus photography and fluorescein angiography 15

tutorial

Fundus photography and fluorescein angiography

Don Wong, RBP

Department of OphthalmologyCabrini Health Care Center

New York, New York

Photography in ophthalmology and the apparatus

Photography has progressed con-siderably since the first permanent pho-tographic record by Niepce in 1826. Thepioneering work of Louis-Jacque Dag-uerre and Henry Fox Talbot and others iswell accounted in other texts (Newhall,1974, and Gernsheim, 1968). The earlygrowth of photography occurred mainlybecause of the natural interest in por-traits.

The professional position enjoyed bythe portrait photographer in the mid-1880s is understandably strong. Literallythousands of studios were established theworld-over to service the demands forportraits. In 1852, however, photographyfound its way into the field of medicine,Dr. Behrendt of Berlin (Dommasch, 1965)photographed orthopedic patients beforeand after treatment. He was the first topublish an article in which photographyof patients was mentioned. Most clinicalphotography was done in the portraitstudio with the influence of the portraitphotographer in clear evidence. Theclinical photographs of that era displayedthe patient against opulent, ornatebackdrops and furnishings. In the late1800s photographic illustrations began toappear regularly in medical journals.

In 1889, Dr. Frederick Zimmer ofRochester, New York, utilized a revolu-tionary camera introduced to the marketby George Eastman of Rochester (Corn-well, 1947). The camera was known as theNumber One Kodak Camera and was thefirst successful roll-film camera made.This camera utilized sensitized paper thathad a capacity of 100 pictures. The cam-era was sent to the processing lab with theexposed paper enclosed, where it wasunloaded in the dark and processed. Thecamera was then reloaded and returnedto the customer along with the prints.

Since Dr. Zimmer elected to have themanufacturer process his pictures, heexperienced a delay of seven months fromthe time the first picture was made untilthe paper negative was processed and hewas able to see his clinical photos.

Fundus illustration andphotography

Helmholtz's paper "BeschreibungEines Augenspiegels Zur UntersuchungDer Netzaut Im. Lebenden Augel," pub-lished in Berlin in 1851, introduced theophthalmoscope to the ophthalmologist(Wallace, 1919). Though he included adrawing of the instrument, nothing wasoffered which gave the reader any idea ofwhat he was able to see with his instru-ment. The earliest known paper whichcontained illustrations of the fundus(Wallace, 1919) was printed in 1853 by A.C. Van Trigt. It was entitled "De SpeculoOculi". Seven drawings in black and whiteaccompanied the article in which the au-thor describes various eye conditions.Early papers and discussions by physi-cians indicated that the Helmholtzophthalmoscope was not of satisfactorydesign, resulting in numerous attempts tofind something better.

The first known attempt at fundusphotography was made by Dr. HenryNoyes of New York in 1862 (Mann, 1970).He reported his work at the InternationalMedical Congress of 1884, describing anapparatus that he made in an attempt tophotograph the "retinal vessels in the eyeof a rabbit." These attempts, as wereother early ones, were abandoned due toinsurmountable problems, i.e., the veryslow sensitivity of the photographic ma-terials, as well as glaring reflexes off thecornea.

The first known successful fundusphotograph of a living human eye waspublished in 1886 in the PhiladelphiaPhotographer (June 5, 1886) as well as inthe Photographic News (London). Thephotograph was taken by W. T. Jackmanand J. D. Webster of England. Their ap-paratus consisted of a small camera at-tached to the head of the patient and anophthalmoscopic mirror placed at 45° tothe camera lens, which deflected lightfrom a source placed near the patient'sear. Exposure time was two and a halfminutes. The resultant picture was verypoor in detail with a large corneal reflexin the center, which all but obscured ret-inal details. In the following year, 1887, E.Barr of Buffalo, New York, also obtainedresults which he claimed were improvedby the use of orthochromatic plates.During that same time, still a third phy-sician, Dr. Lucien Howe of New York,claimed to have made the first photo-graphs of the human fundus. This wasreported at the American Ophthalmo-logical Society in 1887. His photographs,which required a ten-minute exposuretime, were also poor in detail and hadcorneal reflexes.

It was not until 1899 that the firstreflex-free photographs of the humanfundus were shown by Dimmer at theInternational Congress. Working with theZeiss Company of Jena, an apparatus wasconstructed which was very large andunwieldy. Exposure times were in theorder of four to five seconds, resulting inblurry pictures due to eye movements.Three years later, greatly improved re-sults were obtained through the use of acarbon arc illuminating source which al-lowed the use of exposures of 1/10 second.Additionally, decentration of the objec-tive lenses eliminated the corneal reflexes,

16 Journal of Ophthalmic Photography Vol. 2, No. 3 August 1979

making it possible to photograph a largerarea of the fundus. A collection of thesephotographs were published in the firstatlas of fundus photography in 1907. Asecond atlas was published after Dim-mer's death in 1927. These atlases serveas landmarks in fundus photography.

It is interesting to note that Dimmerwas not alone in his work on an apparatusto perform fundus photography; Dr. W.Thorner and Dr. Wolfe also producedfundus photographs. A bitter controversyarose between Thorner and Dimmer,caused by the fact that Thorner's photo-graphs were poorly illuminated and in-cluded a bad corneal reflex. He accusedDimmer of retouching his photographs.Several years later, Thorner constructedthe first stereoscopic fundus camera,(Thorner, 1909).

Gullstrand, (1910) described a newmethod of reflex-free ophthalmoscopy,referred to as central ophthalmoscopy,which was to become the basis of designfor all later conventional fundus cameras.Nordenson, working with the Zeiss Com-pany, utilized this principle to develop thefirst practical, commercially availablefundus camera. He showed examples ofpictures made with his early apparatus atan International Congress of Ophthal-mology, which was held in Washington in1922. After many modifications, thecamera was introduced to the market in1926. This camera utilized a carbon-arcilluminating source and an optical systemthat allowed for continuous viewing up tothe time of exposure. Later, the camerawas modified even further by Hartinger(1936) who replaced the carbon arc withan electric lamp. In 1936, in collaborationwith Boeghold, Hartinger developed thereflex-free ophthalmoscopic lens with asmall black dot etched in the middle. Thislens design was also to he incorporatedinto future fundus cameras.

Just before the marketing of Nor-denson's camera, a Dutch ophthalmolo-gist, Salomonson of Amsterdam, pre-sented a paper at the 1925 AmericanMedical Association meeting held in At-lantic City, New Jersey, in which he de-scribed his "recording ophthalmoscope."Two optical systems made up this appa-ratus, one for illumination and the otherfor photography. This camera also uti-lized the carbon arc as a light source andallowed an exposure time of about 1/10second. The camera apparently did notproduce the quality results that the ZeissNordenson camera did, and therefore, wasnever developed commercially. The

Nordenson camera appeared in numeroushospital clinics and physicians' officesthroughout the world, and due to its rel-ative ease of handling became an impor-tant part of clinical ophthalmology.

It is generally acknowledged by manyin ophthalmology (Meyer-Schwickerath,1968) that the one man most responsiblefor convincing physicians the world overof the value of the fundus photograph asa permanent documentary record as wellas a teaching aid was Dr. Arthur J. Bedellof Albany, New York. In one of his earlypapers, published in the New York StateJournal of Medicine, (Bedell, 1927) 115original photographs, along with detailedcase histories, were presented, which wonDr. Bedell the Lucien-Howe prize. Aneditorial in that issue urged all physiciansto "preserve these photographs for ref-erence and study." The article includeddetailed descriptions of the camera sys-tem as well as operating procedures. Dr.Bedell was to continue as the leading ex-ponent of fundus photography in theUnited States, and later was to claim tohave taken over 130 thousand fundusphotographs. An Atlas of his work waspublished in 1929, Photographs of theFundus Oculi.

After the end of World War II, theelectronic flash tube was introducedinto the camera system as an illuminat-ing source for photography.

Meyer-Schwickerath and Niesel (Meyer-Schwickerath, 1954) in 1953 and Littman(1965) in 1955, incorporated the electronicflash in the modern Zeiss fundus camera.This intense source was an importantfactor which made possible the work ofNovotney and Alvis (1961). Their paper, A Method of Photographing Fluores-cence in Circulating Blood in the HumanRetina, was published in 1961 and provedto he a significant contribution, as well asthe catalyst for the establishment of flu-orescein angiography as a clinical diag-nostic test procedure in ophthalmology.This ability to photograph the circulationfollowing the injection of fluorescein dyeonce again gave the physician goals thatthe existing equipment could not satis-factorily meet. Once again, the illumina-tion was insufficient, the film emulsionsnot sensitive enough and the rate of pho-tography too slow.

Novotney and. Alvis were not satis-fied with single-frame photography afterinjection of the dye, a method imposed bythe existing equipment. They attemptedto develop a technique which would resultin a higher rate of photography. Motion-

picture studies of the human eye in 1961were largely unsuccessful due to the highintensities bf light levels required. Pavia(1933) adapted a Zeiss-Nordenson funduscamera for motion pictures as early as1933; in 1957, Chao and Flocks (1958)described a method of calculating thecirculation time of a cat's retina byophthalmoscopy, following injection of 1%aqueous Trypan Blue into the internalcarotid artery. One year later, in 1958,(Flocks, Miller and Chas, 1959), they de-scribed their work in "the determinationof retinal circulation time with the aid offundus cinephotography." In this work,a Kodak 16 mm Cine-Special camera wasadapted to the Zeiss-Nordenson camera,and motion pictures were made througha cobalt blue filter at twenty frames persecond to record the passage of fluoresceinthrough a cat's retina. Super Ansco-chrome film (ASA 100) was used. Theirtime recording device was an ingeniouspaddle six degrees in width and turned bya 30 RPM synchronous motor, causing thepaddle to pass across the light path onceevery second. In 1962, this author adapteda 16 mm Rolex camera to the modernZeiss fundus camera for motion picturestudies of the effect of freezing on a cat'sretina. This was done to determine thefeasibility of applying cryosurgery toophthalmology. Super Anscochrome film(ASA 500) was exposed at 12 frames persecond by over-loading the focusing illu-mination of the fundus camera.

Early motion picture work to recordpassage of fluorescein dye was successfuldue to a great deal of customizing ofequipment. Norton (Miami), Dollery(London), Oosterhuis and Ammens(Netherlands) and Wessing and Littmann(Germany) all achieved a good degree ofsuccess in this medium. Cinematographyfinally gave way to the closed-circuit TVcamera, which is capable of producingpictures of fairly high quality with mini-mal light levels. Some leading institutionshave included video taping into theirfluorescein angiographic programs, witha great deal of success.

In the century and a half that haspassed since the beginning of photogra-phy, numerous inventive individuals havecontributed to the development of thechemical processes of photography, theclinical techniques of ophthalmoscopyand the instrumentation required tocombine these two into the art of fundusphotography. A search through the liter-ature reveals the determination and per-sistence of the early scientists, who in

Figure 1—A cross section of the Zeiss-Nordenson fundus camera. The incident light beam is projectedout of the carbon arc housing by means of two prisms, through the camera optical system and intothe inferior portion of the dilated pupil. The reflected beam emerges from the eye through the centralpupil.

Figure 2—Diagrammatic cross-sections of four modern fundus cameras for comparisonto the Zeiss-Nordenson as shown in Figure 1.

Don Wong, RBP Fundus photography and fluorescein angiography 17

spite of constant failure still envisionedultimate success. Many recognized at anearly date the value of photographicdocumentation. This was demonstratedby a physician, Dr. B. Joy Jeffries ofBoston, who published an article in theTransactions of the American Ophthal-mological Society of 1869 (Jeffries, 1869).Dr. Jeffries described a case of a youngboy seen in consultation who was kickedin the head by a horse, and who eventuallylost his vision. The doctor wrote:

.. But that which is of special in-terest, and my reason for reportingthis case is, that we here have a per-fectly normal fundus oculi entirelydestitute of sensation of light, andwith transparent media in front ofit. From not being able to communi-cate in time with Dr. Noyes of NewYork, who possesses the necessaryskill and apparatus, an opportunitywas lost to achieve a scientifictriumph, namely the photographingof the interior of a normal humaneye, which I believe has not yet beendone."

ApparatusThe instruments and devices created

by the early workers were truly cumber-some and awkward to work with due tothe great limitation imposed upon thescientists by the technology of the times.The very slow film emulsions sensitizedprimarily to blue forced the use of in-credibly long exposure times (Howe's 10minutes, and Jackson and Webster's 21/2minutes). Dimmer's first application ofthe carbon arc and Gullstrand's achieve-ment in central reflex-free ophthalmos-copy paved the way for modern fundusphotography. Dr. J. W. Nordenson's workwith the Carl Zeiss Jena Optical Compa-ny, which spans about fifteen years, re-sulted in a camera of radical design. Thisinstrument, slightly larger than Gull-strand's simplified ophthalmoscope andonly a fraction of the size of Dimmer'sapparatus, was to revolutionize fundusphotography and establish it as a routineclinical procedure. Because the cameraoccupied less than two square feet of tablespace and could be placed on a small tablefor use, the camera gained great popu-larity, and numerous units were pur-chased for hospitals and private offices.

A diagrammatic section (Figure 1) ofthe Nordenson camera (Anon., 1936)shows how the small carbon-arc lamp ismounted over the barrel of the fundus

18 Journal of Ophthalmic Photography Vol. 2, No. 1 August 1979

Year 1967 1973 1976FISBA RECA-1 Jena Retinophot Jena RetinophotKowa RC-2 Kowa RC-2 Kowa RC-2Mamiya R-1 Mamiya FR-200 Mamiya FR-200

Fundus Nikon Hand Nikon Retinapan 45 Mamiya FR-300Noyori Hand Olympus GRC FF H Olympus GRC FF II

Cameras Olympus GRC Olympus PRC Olympus PRCO.P.L. Model 56 Topcon J Topcon TRC-JAvailable Jena Retinophot Topcon TRC-F Topcon TRC-FZeiss Seimens Topcon TRC-F3 Topcon TRC-F3

Zeiss Seimens Topcon TRC-FEZeiss Dyonics Topcon TRC-FE3Zeiss FF II Topcon TRC-FE300Zeiss FF III Topcon TRC-FE800

Zeiss SiemensZeiss DyonicsZeiss FF IIZeiss FF IIIDonaldson StereoClinitex 1000Pomerantzeff Equator Plus

Figure 3—The fundus cameras available in 1967, 1973, and 1976. in 1976 a small number of man-ufacturers have available several instrument models to keep pace with the changing technology andapplications.

camera, and by a system of optics,projects an incident beam of light onto thelower portion of the dilated pupil. Thereflected beam exists the eye through thecentral cornea and an inverted image ofthe retina is formed by the newly-de-signed ophthalmoscopic lens within thebarrel of the camera. The photographicobjective is focused on this image andprojects it back onto the reflex mirror ofthe photographic camera assembly and uponto the plane of the crosshairs. The fo-cusing lens of the finder magnifies theimage by about 5 times for viewing. Whenthe image is critically focused and thefield composed, the shutter is released. Agray glass filter, which is situated in theillumination pathway to cut the intensityof light to tolerable levels for the patientduring the photographic session, auto-matically swings away to allow the fullintensity of the carbon arc to be projectedinto the eye for exposure, and the reflexmirror is raised to allow a clear pathwayback to the film.

With the advent of World War II,production of the Nordenson camerastopped. The Bausch and Lomb Compa-ny marketed a version of this carbon-arcfundus camera, but its numbers werelimited and no further attempts byAmerican optical manufacturers to makefundus camera equipment have takenplace. After the end of the war, both Eu-ropean and Japanese manufacturers re-sumed production of fundus cameras.

The current status of instrumenta-tion in the field today consists of con-ventional camera systems put onto themarket by seven major companies (Wong,1976) as well as a number of specializedsystems and instruments designed forspecial purposes. Each unit, however,utilizes the same principles of the Zeiss-Nordenson camera, with only slightvariations (Figure 2). Each camera utilizestwo independent illuminating sources,one a low-intensity incandescent bulb forfocusing and composition and the othera high-intensity electronic flash tube forexposure. Both sources share the sameoptical pathway. Whereas the Nordensonsystem projected the illuminating beamonto the inferior portion of the corneawith the image-forming reflected beampassing through the more symmetricalcentral cornea, the modern cameras gen-erally utilize a ring of light surrounding acentral shadow area. The ring representsthe incident beam and passes throughperipheral cornea superiorly and inferi-orly, while the reflected beam travelsalong the pathway through the shadowarea centrally. A review (Figure 3) of theinstruments available and in use todaycompared to those available two years ago(de Kerk, 1973) and those available eightyears ago (Hansell, 1967) demonstratesthe great state of flux that the industrywas in. In 1967, seven manufacturers puton the market six table models and threehand fundus cameras. In 1973, the num-

ber of firms offering equipment remainedat seven, yet two were new companies,replacing two which stopped production.Between these seven firms, eleven dif-ferent table-model camera systems andthree hand fundus cameras were availableas well as several sophisticated "special-ized" systems devised for special-purposework. Today, in 1976, only six firms areleft in production, yet there are fifteentable-model systems and two hand funduscameras, as well as the Donaldson Stereofundus camera. There are also two wide-angle contact lens cameras. One. theClinitex 100° camera, and the other is thePomerantzeff Equator-Plus wide-anglecamera. The following is a brief summaryof the major units in use today. It is safeto say that all angiographic work beingdone today in North America is primarilybeing done with the Zeiss system, andsecondarily, with the Topcon.

The Jena RetinophotThe Retinophot is a table-model

camera mounted onto a vertical center-post, in turn set into a sliding table-topbase. The camera is powered by a so-phisticated program unit, which enablesone to select the rapid-sequence cycledesired. Delay time after injection may beestablished by one control that automat-ically initiates photography after zerotime. (The photographer activates thestarting button at the beginning of theinjection, steps on the foot switch and the

Don Wong, RBP Fundus photography and fluorescein angiography 19

program unit takes over, electronicallytiming the delay time, then commencingrapid-sequence photography automati-cally.) The rate of photography is preset,as are the number of exposures to be madein the rapid sequence. The final portionof the angiographic study is also preset toactivate the camera at certain intervalsafter cessation of the rapid-sequencephotography (e.g., one picture every twoor four seconds may be made automati-cally). In this way, the entire angiographicprogram may be preset, requiring thephotographer to activate the startingbutton only at the beginning of the in-jection. The angle of view is 28° and theworking distance is 8 mm.

Kowa RC-2 fundus cameraThis is a very versatile camera, which

in the hands of an experienced person iscapable of producing excellent fundusphotographs. Current models feature aspecial power supply for angiographicwork and a motor drive film advance. Thecamera is portable but also utilizes a smallstand to allow for table-top use. Polaroidfilm packs can also be used. It weighs only2.2 pounds, making it fairly easy to use asa hand-held camera. Satisfactory anteriorchamber angle photographs, external eyephotographs and even deep cavity pic-tures (for example, intraoral) may be ob-tained with relative ease. The angle ofview is 30° and the working distance is ashort 8 mm to the cornea.

Mamiya FR200 and FR300fundus cameras

The Mamiya Company offers twotable-model cameras, the FR200 andFR300 cameras, which utilize a mirrorsystem to render the images, rather thanan aspherical ophthalmoscopic lens. Bothof these cameras have a full range of ac-cessories such as tele-extender lenses forhigh-magnification pictures, Polaroidadapter and remote-control foot-switchreleases. The cameras, however, are pri-marily in use in Japan and have not yetcome to the American market. The angleof view is 30° and the working distance is30 mm.

Nikon Retinapan 45 andNikon hand fundus cameras

In 1970, the Nikon Company intro-duced to the American market the Reti-napan 45, a table model, which featureda radically wider field of view (45°) thanother cameras in use at the time. It alsofeatured a new pantographic tilt mecha-

nism. This made it the second camera onthe market to be adjustable in the verticalplane. Production difficulties have takenthis unit off the market, but the companyanticipates a modified version in the fu-ture. The Nikon hand fundus camera wascapable of doing color photography only,providing a 2.5X image in a 30° view. Thecamera weighs 3 1/2 pounds and has a 10mm working distance to the cornea.

Olympus GRC FFII and PRChand fundus cameras

The Olympus GRC II table-modelfundus camera is not on the Americanmarket, being restricted primarily to theJapanese consumer. The camera has anangle of view of 28° and has a workingdistance of 70 mm to the cornea. The PRChand fundus camera is distributed inAmerica by the Codman-Mentor Com-pany. The camera body used is the Ol-ympus PEN-F, a half-frame single-lensreflex camera enabling one to obtain twicethe number of pictures on a roll of filmthan can be obtained with full-framecameras. The apparatus weighs a littleless than two pounds and the workingdistance is 6.7 min.

Topcon fundus camerasThe Topcon Company first intro-

duced their line of fundus cameras in 1965with the Model 1 camera, followed oneyear later with their first angiographicunit, the Model 2; Their equipment hasbecome increasingly popular on theAmerican market over the past severalyears and is found primarily in physicians'private offices. In September, 1975, acompletely new camera was introduced atthe Annual Meeting of the AmericanAcademy of Ophthalmology and Otolar-yngology. Designated the TRC -FE,TRC-FE3, TRC-FE300 and TRC-FE800,these systems bring the total number ofcameras offered by the company toseven.

The power sources

The TRC-J is the smallest of theTopcon power sources that delivers only50 watt-seconds of light energy, thus re-stricting this unit to color fundus pho-tography. The TRC-F is the smaller of thetwo sources designed for angiographywith a maximum flash output of 300watt-seconds, adjustable over five stages.It has a recycling time of one second. Thispower pack utilizes 100 volt AC through240 volts AC which is adjustable via a se-lector button over six settings, making it

very simple to install. One must merelyset the voltage selector button at thevoltage which is available. The larger ofthe two power sources for angiography,the TRC-F3, is quite heavy (121 lbs) andis mounted on casters. This power packrequires the use of 200 V, 220 V or 240 VAC and should have a line installed for itsown use. The flash output is a maximumof 350 watt-seconds, adjustable over sixlevels, and has a recycling time of 0.3seconds.

The fundus camera

The original Topcon fundus camera(Figure 4A) is mounted onto a verticalcenter post, which is fixed onto a floatingpositioning plate, which in turn is set ontoa small base. The headrest and chinrestassembly is permanently fixed into thepatient's end of the camera base. Thisunit may be placed onto any small tablefor use. Since the camera is mounted ontoa vertical center post, which has limitedtransverse movement, the camera is firstpositioned at the midline of the patient'shead, then swung to the right or lefttowards the eye to be photographed.

The Topcon camera has a data re-cording system which enables one to rec-ord either consecutive frame numbers orelapsed time in seconds. This is recordedon the film adjacent to the picture area.Additionally, the photographer also hasthe option of recording either the pa-tient's name or identifying number oneach frame by writing this data onto a slipof paper and inserting it into the appro-priate slot on the time data device.

Two controls are located on the leftside of the fund us camera body, one is adiopter lens selector button, which allowsfor the selection of lenses of differentdiopter strengths for photography. Thesecond of these controls is the filter wheelon which the excitation filter for angiog-raphy is installed. A small knob situatedon top of the camera controls barrier fil-ters and other apertures that are generallyused for f-stop control. Topcon providestheir own BA interference filters as wellas a Kodak Wratten filter, no. 15 (yellow),as a barrier filter for angiography.

Three major changes in the design ofthe fundus camera body give greatly in-creased versatility to the Topcon FRC-FEand TRC-FET instruments. (Figure 4B)The headrest and chin-rest assembly is nolonger on the same base on the funduscamera body, which allows manipulationof the camera to subject to a greater de-gree than before. More importantly, the

20 Journal 01 Ophthalmic Photography Vol. 2, No, 1 August 1979

A

Figure 4A—The Topcon fundus camera, TRC-F. B—The Topcon TRC-FET.

pivotal point of the camera body wastaken off the vertical center post andmoved to a point forward of the ophthal-moscopic lens, enabling a lateral swing ofthe optical head up to 30° with an unin-terrupted view. On the TRC-FET model,a tilt mechanism is now featured, per-mitting a vertical displacement of thecamera of 15° from zero, making periph-eral photography of the superior and in-ferior fundus a great deal simpler. Thetrigger release for photography is on thejoy-stick, giving great convenience in thephotographic sessions.

All viewing and composing is donethrough the eyepiece of the 35 mm camerabody that is used. The body used on theearly systems (TRC-J, TRC-F, TRC-F3)is the excellent Topcon M single-lens re-flex camera equipped with an electronicmotor. The camera is also used manuallyfor single-frame color photography.

The camera bodies provided with thenew system (TRC-FE, TRC-FET) are thetype AM and AM-FL single-lens reflexcameras. These are operated manually,with an Autowinder, or with a motor drivesystem. The Autowinder is an electronicdrive used to control such the operationsof the body as shutter release, automatic

film advance and cocking of the shutterfor the next exposure. The device is notcapable of providing continuous photog-raphy, but is used for single-frame pho-tography. The motor drive, however, is acompletely automatic device that permitscontinuous sequential photography aslong as the trigger is depressed.

The power generators available forthese new model cameras are the 300 and800 series. Both feature an automatic in-jector; the 300 series delivers 300 watt-seconds of light and has a recycling timefor 3 flashes per second, while the 800 se-ries, delivering the same light output,recycles for 8 flashes per second.

Accessories

A fairly wide range of accessories isavailable for the Topcon system, includ-ing a 1.8X magnifying extension tube anda stereo attachment that fits over thefront of the camera. There is also thesighting mirror attachment. This is aprism that is slipped over the front lensbarrel and allows the photographer tolook over the top of the fund us camera atthe prism to determine whether or not thealignment of the camera to the eye is stillcorrect. This is considerably easier and

less time consuming than leaning off tothe side of the camera.

Two Polaroid systems are available,the Polaroid attachment Type I, which issimply attached to the 35mm camerabody piggyback-style after the hingedback is removed. The new attachment,Type II, is mounted directly to the hackof the fundus camera. This adaptor usesonly 40 mm of a single sheet of film, whichmeans that two images may be madeside-by-side on a single sheet of Polaroidfilm type 107 or type 108.

The Zeiss fundus camerasystem

The Zeiss Company is the pioneerfirm in fundus photography, and since thecreation of the Zeiss-Nordenson camera,the company has been the moving force inthe field. Their instrumentation is notonly well-known in fundus photography,but in other areas of ophthalmic photog-raphy as well. Thus, in the early 1960s,recognizing the potential significance offluorescein angiography, Zeiss producedtheir first angiographic unit, which cameto the American market in 1966. Calledthe Automatic Fluorescein AngiographicFundus Camera System, it utilized a 35

Don Wong, RBP Fundus photography and fluorescein angiography 21

mm Robot automatic camera body com-bined with a very large power generator,the Siemens power pack.

Within a year's time, this system wasto undergo the first of many modifica-tions, and subsequently, the company hasmarketed four major systems, each witha host of different optical parts as well asdifferent camera bodies, eyepieceassemblies and accessories. This makesthe Zeiss system the must versatile, com-plex system on the market.

It is possible to see numerous varia-tions of the apparatus in use, dependingupon the particular component partsutilized, which means that a photographermay need to go through a brief period oforientation as he goes from one lab toanother.

For discussion purposes, the camerasystem may be divided into the followingcomponents: the fund us camera (less theeyepiece assembly); the eyepiece assem-bly, of which there are four; the 35 mmcamera body; and the power generatorsystem, from which each model derives itsname.

Shortly after the introduction of theautomatic angiographic camera system in1966, Zeiss, in conjunction with a com-mercial firm known as Ule (later, Dyon-ics), marketed a unit known as theDyonics CineFlash, capable of veryhigh-speed photography, and requiring aliquid refrigerant to cool the unit. Allsubsequent modifications in design weredone by the Zeiss Company itself. Theseunits were the Fundus Flash II (FF II),the Power Pack 260 and most currentlythe Fundus Flash III (FF III).

The fundus camera

Unlike other models, which are fixedonto a permanent base, the Zeiss funduscamera is mounted onto a base which canglide over a table surface on rollers in atransverse manner, enabling one to posi-tion the apparatus directly in front of theeye being photographed. The camera ismounted onto this base by a vertical col-umn situated at a critical point in front ofthe instrument, which enables the camerato he swung from right to left withoutlosing its alignment within the dilatedpupil. It is therefore possible for one totake a series of pictures in quick succes-sion merely by swinging the camera firstto the temporal then to the nasal side ofthe first view photograph. The cameraposition may also be altered in the verticalplane by a tilting mechanism, which en-ables the apparatus to be tilted up or

down without losing its original alignmentwithin the dilated pupil. These featuresare most important during serial angiog-raphy when small adjustments are re-quired to follow a drifting eye in order tomaintain optimum camera positionwithout interruption of photography. Theability of the instrument to be positioneddirectly in front of the eye to be photo-graphed, combined with the swing and tiltmovements of the camera, give this sys-tem maximum versatility and a great ad-vantage over other units. A built-in fixa-tion device originally intended to be usedto demonstrate eccentric fixation is lo-cated on the front of the fund us camerabody, and may be used to great advantagefor patients who cannot see the targetlight with the fellow eye. On the FF IIIfundus camera, a filter slot is situated onthe side of the instrument, which enablesone to easily insert filters for photogra-phy:

The camera tables have two elevatingand lowering controls. One located be-neath the table elevates and lowers theentire apparatus for the patient's height.The second is a flat white knob located inthe middle of the table top just forward ofthe joystick. This control raises or lowersthe camera only, and is independent ofthe headrest and chinrest assembly, en-abling one to change the height of thecamera in relation to the eye to followslight eye movements in the verticalplane. The headrest and chinrest assem-bly is manueverable by means of aknurled knob located to the photogra-pher's left, just under the table. This knobis used for gross adjustments of the pa-tient-to-camera distance.

Optically, the system is superb, witha wide range of accessory lenses to provideample coverage for critical focus on thehyperopic eye as well as on the myopiceye. Additionally, an astigmatic correctioncontrol is situated at the top of the funduscamera body.

Eyepiece assemblies

Unlike other units, the Zeiss funduscamera's eyepiece assembly is a completeindependent system (Figure 5) which maybe removed from the fundus camera bodyand which has numerous combinations offittings for 35 mm camera bodies. Fourdifferent eyepiece assemblies are in usetoday, the oldest of which was utilized onthe automatic fluorescein angiographiccamera. This system was soon replaced bya more versatile one, which appeared onthe FF II fundus camera.

22 Journal of Ophthalmic Photography Vol. 2, No. 1 August 1979

A

C D

Figure 5—The Zeiss Eyepiece Assemblies. A—Automatic Robot eyepiece. B—FF II with Databoxand motorized Pentax camera body. C—Prism eyepiece head. D—Solenoid mirror eyepiece.

Don Wong, RBP Fundus photography and fluorescein angiography 23

A digital time-recording device wasincluded on the FF II model, replacing thesweeping-second-hand clock utilized bythe Robot camera. For single-frame pho-tography, exposures are made by de-pressing a black lever arm in which twowhite plastic plugs are inserted. Themirror in the eyepiece is attached to thislever so that as the arm is depressed, themirror also is, and is dropped out of thephotographic pathway to allow the lighthack to the film. At the instant the mirrordrops, the eyepiece is blacked out. As thearm continues downward, the plasticplugs come into contact with the shutterrelease button of the 35 mm camera body,and slight further pressure downwardsthe shutter for the exposure. The secondwhite plug at the end of this lever makescontact with the shutter release button ofthe camera body when the 2X magnifyinglens is in place for photography.

After a period of constant usage, acommon occurrence that one encountersis slippage of the white plastic plugs awayfrom the optimum positions, causing avariety of photographic artifacts to ap-pear. If the plugs are too high, greater-than-normal pressure must be exertedonto the arm in order to get the plug toreach the shutter release button of thecamera body, causing the mirror to hit thedamper at the base of the eyepiece as-sembly with excessive force and to bounceback upwards into the photographicpathway. If the plugs have slipped too fardown, the shutter release button of thecamera body is activated prematurely,and the photograph is made while themirror is still on its way down. Both theseconditions result in photographs with themirror of the eyepiece assembly intrudinginto the photographic pathway, and onemust be able to recognize the malfunctionin order to take the proper correctivesteps.

One clue that is helpful is that onthose pictures in which the mirror hits thedamper and bounces upwards, the shad-ow of the mirror in the picture area at 6o'clock is often accompanied by a half-moon crescent of light at the 12 o'clockposition. The photographer may correctthis misalignment by loosening the smallretaining screws holding the plugs in placeand resetting the position of the plug. Inorder to do this correctly, he must pressthe lever down gently until he hears themirror tap against the damper. Repeatedmovements will confirm that position.Holding the lever in that position, thephotographer must adjust the plug until

it barely comes into contact with theshutter release button of the camera body.The photographer should make severaltest moves to confirm that the plug is incontact with the shutter release button asthe mirror hits the damper, then heshould tighten the retaining screw. It isadvisable thereafter to check these ad-justments periodically to prevent loss ofpictures due to the cut-off of the image bythe mirror.

Prism assembly

Recently, Zeiss marketed an eyepieceassembly that utilizes a set of prisms in-stead of moving mirrors, thus eliminatingthe lever arm and a moving part in thatassembly. In this way, the problems at-tendant with the use of the plastic plugsto activate the camera shutter are alsoeliminated. Exposures are made by de-pressing the shutter release button of thecamera body directly. The photographermust adjust to the use of this assembly,especially during angiography, becausesome of the light reflected out of the pa-tient's eye is diverted up into the eyepieceand into the photographer's eye. This willcause him to lose his dark adaptation.

Mirror assembly

The fourth eyepiece assembly in-corporates a mirror which is solenoid-activated and is powered by the powergenerator. The use of the solenoid elimi-nates the need for the lever arm mecha-nism while still retaining the movingmirror which blacks out the eyepiece atthe moment of photography. This pre-serves the photographer's dark adapta-tion.

A number of 35 mm camera bodiesare in use today with these assemblies,each requiring the appropriate adapterring. Zeiss' own Special ikon body was thework-horse of single frame color photog-raphy, and some institutions even per-formed their angiographies with thesebodies by depressing the lever for expo-sure and advancing the film and cockingthe shutter manually. The motorizedNikon F camera body was adapted at avery early stage of instrumentation forangiography by the Dyonics Company,enabling rapid-sequence photography tobe performed at the rate of 4 frames persecond. Soon afterwards, the motorizedLeica replaced the Nikon system on theFF II fundus camera, and finally, themotorized Honeywell Pentax SpotmaticII replaced the Leica on the FF III. Eachsystem proved to be quite reliable but the

Nikon and Pentax had the added versa-tility of a 250-exposure film chamber.

Power generator

The Siemens power generator (Fig-ure 6, page 114) requires 220 volts AC foroperation, and it is recommended that aseparate electrical line be installed for thisunit alone. One must be careful in thecombination of settings used with thispack to prevent overloading with thesurge of input power, which might causethe circuit breakers to shut down thesystem. If the circuit breakers do shutdown, it usually occurs during a serial run,causing the electronic flash tube to igniteand remain very brightly lit for a secondor so (accompanied by a humming sound),all of which is followed by a loud snap asthe circuit breakers switch off. Photog-raphy may be resumed after resetting thecircuit breakers, which are situated on thelower right-hand corner of the genera-tor.

The Dyonics Cineflash powersupplies (models No. 708, No. 730 and No.760) were developed by the Ule Corpora-tion (later Dyonics) of Woburn, Massa-chusetts to be used in conjunction withthe Zeiss Fundus camera. They wereespecially adapted for very high-speedphotography with a maximum of 60frames per second. These units are quitecomplex, having automatic built-in de-layed timing devices as well as an auto-matically controlled photography rate.Control outlets on the Cineflash areavailable for numerous accessories. Thesepower supplies are capable of such high-speed recycling without overheating dueto a liquid coolant system. The Dyonicsline includes eyepiece assemblies adaptedfor motorized Nikons (4 frames per sec-ond) as well as for 35 mm Arriflex motionpicture cameras and camera systems(Vidicon High Speed or Image Orthocon).The models No. 708 and No. 730 bothhave only one flash output (200 watt-seconds), whereas the No. 760 has two(100 watt-seconds and 200 watt-seconds).Neutral density filters control the expo-sure for color photography.

The Fundus Flash H (FF II) powergenerator is physically the largest of Zeiss'power sources, utilizing 115 volts AC, hasonly three levels of flash output, which aredesignated low, medium and high. Onedoes have the option of installing aBooster Unit onto the original. FFpower pack, giving a maximum of 240watt-seconds. The booster is operationalonly when the flash output selector switch

Figure 6—Zeiss Power generators. A—Siemens Power Pack. B—Dyonics Power Pack. C--FF II.D—Power Pack 260. E—FF III.

24 Journal of Ophthalmic Photography Vol. 2, No. 1 August 1979

is set on the "high" position. The circuitbreaker, situated at the back of the gen-erator is fused for 20 amps. In the eventthe surge of power during the serial angi-ography causes the circuit breaker to shutdown, one merely has to reset the breakerand resume photography at a slower rate.It is advisable to install an electrical lineto service only this apparatus.

The Power Supply 260 is physicallythe smallest of Zeiss' power sources forangiography. Its recycling capabilities arenot as fast as the larger units are, yet it isperfectly suitable for clinical angiography.This power pack has no provision formotorized rapid-sequence photographyor other accessories such as a a remote-

control foot switch or a stereo photogra-phy device. All photography and angiog-raphy must he performed manually. (Amotorized Pentax camera may be used,but an additional DC power source mustbe utilized to activate the camera.)

The Fundus Flash Ill (FF III) hasevolved from all previous systems andencompasses some of the best features ofeach. It is small in size, yet has a gooddelivery of light (maximum output 350watt-seconds); it has built-in outlets forthe stereo adapter and motorized drive forthe camera; it has a rheostat for the fixa-tion light intensity; it has foot switchcontrol for a focusing light overload; andit has the capability to connect two in-

struments into this one power generator.A selector switch marked "System 1" and"System 2" diverts the electrical powerfrom one apparatus to the other so that itis possible to utilize this one power sourceto service two instruments (either twofundus cameras, or a fundus camera andan iris angiographic unit though not at thesame time).

Accessories

A number of accessories are availablewhich serve to enhance the results ob-tained. A 2X magnifying lens may be in-serted between the 35 mm camera bodyand the back of the fundus camera to ob-tain high-magnification fundus photo-graphs; the Allen Stereo Separator, at-tached over the front barrel of the funduscamera automatically yields stereo fundusphotos; and a Polaroid film back permitsthe use of Polaroid film for instant re-sults.

Finally, the Zeiss Company, in con-junction with the Urban EngineeringCompany of Burbank, California, hasdeveloped the Zeiss-Urban Retinal ImageDisplay System, which is a video systemand which may be mounted onto thecamera in place of the regular eyepieceassembly. This permits one to record an-giography onto videotape cassettes.

Specialized systemsIn addition to the conventional sys-

tems discussed, a number of customizedunits as well as specialized units haveevolved. Generally, the customized unitshave been converted by the consumer inorder to adapt it to highly specializedprojects, and therefore have limited ap-plications. Several other cameras that arediscussed in this section are commerciallymarketed, and are systems of radical de-sign and deserve some note.Donaldson stereo fundus camera.Previously, most stereo fundus photo-graphs have been obtained by taking twoconsecutive pictures which were ulti-mately matched together for viewing.Many technical factors exist which oftencaused difficulty, rendering the two pic-tures ineffective for a good stereo effect.The ideal method of producing such pic-tures is to expose both frames of the stereopair simultaneously. Dr. David Donaldsonof the Harvard Medical School, observingthe lack of such equipment, undertook to"design and make such a fundus cam-era."

Based upon the principle of indirectophthalmoscopy as reported by Donald-

Don Wang, RBP Fundus photography and fluorescein angiography 25

son (1964), the image of the fundus is splitinto different pathways by a "field" lens,which in turn re-images it into the filmplane. Focusing is done through a binoc-ular eyepiece system. The illumination isprovided by two "end-on" electronic flashtubes designed specifically for the cameraby Dr. Harold Edgerton of MasschusettsInstitute of Technology. These tubes alsoprovide the focusing and viewing illumi-nation by flashing 60 times per second (atlow intensity) and then discharging atmaximum output for the exposure. Thecamera is placed on a standard Zeiss tablefor operation.Clinitex loo n contact lens funduscamera. Marketed by the Clinitex Com-pany of Danvers, Massachusetts, thiscamera produces a wide-angle view of thefundus by employing a contact lens as itsfront element. The photographic proce-dure therefore requires that the camera bein constant contact with patient's cornea.This 100° view is considerably greaterthan the 30° view of the conventionalsystems (Figure 7A).Pomerantzeff Equator-Plus contactlens fundus camera. This is a secondwide-angle contact lens camera that wasshown for the first time at the AmericanAcademy of Ophthalmology and Otolar-yngology (AA00) Meeting in Septemberof 1975. The camera produces a picturewith a 150° field of view. It was producedprimarily for black-and-white and colorpictures of the fundus and will have lim-ited angiographic capability. (Figure7B)Multispectral fundus camera. Of thecustomized units in use today, this isprobably the most sophisticated, not onlyin design, but in application. The camerawas converted for use at the AppliedPhysics Laboratory of Johns HopkinsUniversity to study the relative resis-tances to blood flow in the choroidal andretinal vasculatures at very high intra-ocular pressures. This camera performsinfrared absorption angiography with theuse of intravenous indocyanine green(ICG) dye (Flower, 1972). This dye, in amixture with sodium fluorescein alsopermits simultaneous infrared-absorptionstudies of the choroidal vasculature aswell as fluorescein angiographic studies ofthe retinal vasculature (Figure 7C).

Figure 7—Special fundus photography systems. A—Clinitex CA-2 100 contact lens fundus camera.B—Pomerantzeff Equator-Plus contact lens fundus camera. C—Multispectral fundus camera.