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"HOW TO ACHIEVE PERFECT RETINAL PHOTOGRAPHY & FLUORESCEIN ANGIOGRAPHY"
by Scott "Genghis" Wong
Photo by Genghis
An eye with a branch retinal vein occlusion.
I'm going to show you how to have perfect retinal photography and angiography.
That's precisely what you'll have, if you follow my techniques shown in this tutorial.
I'm Scott Wong. I have been working in retinal photography since 1971. I've been teaching the performance of fundus photography and fluorescein angiography for the Joint Commission on Allied Health Personnel in Ophthalmology ( JCAHPO ) since 1981. Between 1981 and 1986, I founded and coordinated JCAHPO's only hands-on fundus photography and fluorescein angiography workshops, where I innovated the first-ever simulated angiography teaching drills. This had never been done, previously. These were the first workshops, where students went through the motions of "shooting" fluorescein angiograms with motorized camera backs attached to fundus cameras, after "injection." These workshops gave students the opportunity to put into practical application in a working setting, the most critically important function that a retinal photographer can do: The performance of fluorescein angiography.
These have since been adopted by the Ophthalmic Photographers' Society (OPS) as what they term "mock angiography" in the OPS' annual workshops. My ground-breaking workshops were seminal in the field of the teaching of retinal photography. Two of the instructors that I recruited for my early 1980s workshops, amie Nicholl and Lawrence Merin, went on to become future presidents of the Ophthalmic Photographers' Society. Since the 1980s, I've continued to give didactic JCAHPO courses in the interpretation of fluorescein angiography and on technique. This tutorial is based on my annual JCAHPO course.
I would like to dedicate this tutorial to my late brother, Don Wong. Don co-founded the Ophthalmic Photographers' Society along with Johnny Justice Jr. and other illustrious medical photogaphers of the day, in 1969.
Don has been my inspiration for all of my life.
The fundamental techniques that we will be examining today, can be brought back to your offices and clinics and applied to either film or digital retinal photography. Let me define what this tutorial is about. It is not about film angiography. It is not about digital retinal photography and angiography. It is about the underlying techniques I've developed that I believe are unique in their specificity in the world of ophthalmic photography, that will enable you to be successful no matter what media system you are using.
You will never see the degree of detail and specificity I'm going to show you in my techniques, in any other teaching venue in retinal photography. Particularly unique in its logic and effectiveness, is my Side To Side, Up and Down, Backward and Forward technique. This technique will give you an incredible degree of camera positioning control.
After you become adept at this technique, you will be able to check your critical camera alignments in a split-second. This will guarantee you perfect angiographic studies, with every single frame of those studies, perfect. More on the side to side, up and down, backward and forward technique later, but let me preface that by saying that with practice, you will be able to do this technqiue, in under one second. The implication of this speed, is that you will be able to check your critical camera positioning, in-between frames of an angiogram, ensuring perfection in every single frame. The "side to side, up and down, backward and forward" technique is a sequential method I developed for myself in the early 1970s, because I wanted a fast and comprehensive way that I could check camera positioning, in a standardized manner. It is repeatable, reliable and ingenious in its straightforward logic and execution.
It is important to remember that although your instrument modality of choice may vary over time depending on job opportunity, that basic techniques of retinal photography and angiography never change. Your ability to obtain and to maintain critical alignments between subject retinas and film planes or digital sensors, which will be taught in this tutorial---are dependent on universal principles of technique which I have formulated and standardized so that they can be easily understood and implemented. It is the underlying techniques that will allow you to acchieve perfect images in your retinal photography and fluorescein angiography. Remember these terms, for they have weighty significance in your underlying technique:
Side to side, up and down, backward and forward.
An historical perspective is useful in beginning our journey. Before retinal photography appeared at the turn of the last century, ophthalmology depended on artwork to document fundus disease in textbooks rich with wonderful illustration. As you might imagine, this required many hours of tedious ophthalmoscopic examination by the ophthalmologist/artists of the day, to get the exquisite detail extant in those textbook illustrations.
This was useful in teaching young ophthalmologists the appearance of disease and afforded them plenty of ophthalmoscopy practice time, but accomplished nothing in terms of day to day image chronicling of their patients' fundus problems. That all changed when fundus photography made its appearance in the 1890s.
The early cameras were primitive devices that were deeply flawed. Some of these filled the better portion of an exam room, where communicating with the patient on the other side of the room proved problematic. The landscape changed when the famous Zeiss-Nordenson retinal camera was introduced in 1926. This innovative design formed the foundation for all modern fundus camera design, with basic changes in design detail since then being minute, overall. The biggest difference between the Zeiss-Nordenson and today's cameras, was that it used a carbon arc lamp for illumination, instead of the electronic flash used today. In the decades following the introduction of the Zeiss-Nordensen camera, ophthalmologists did their own retinal photography. Back then, there were no ancillary personnel for this task. If you ever have a chance to see any retinal images taken with the Zeiss-Nordenson, the excellent image quality of these pictures will impress upon you, how truly advanced this camera was.
Let's first examine some basic parameters that must be met in order to get good results. Ergonomics are not unimportant, and are largely a matter of common sense.
Dark adaptation is important. With that in mind, position the camera and your photography stool close to light switches so that it is ergonomically easy to turn the overhead lights on and off from your shooting position. Inexpensive nightlights can be attached on the camera for illuminating arms for fluorescein injections, so the room lights can be kept off. A timing device for timing the seconds and minutes after injections, and a table for wheeling fluorescein syringes to either side of the camera, are essential. The timing device is critical for your effective control of an angiographic study.
The most important step you can take to begin establishing your command and control in retinal photography to ensure perfect imaging, is to find the gross correct distance between the camera and the eye after you've brought your patient into the chinrest. This is done by looking around the camera at the patient's eye, and focusing the filament of light on the patient's cornea by moving the camera back and forth with the joy stick. This brings the camera into the approximate crtitical alignment along the optical axis. In other words, this technique will bring you into the ballpark, where a miniscule correction either back or forth, will bring you to the absolute correct position along the optical axis.
This critical alignment is represented by a back and forth movement of the joy stick. This is one of two critical alignments you must be concerned with, to attain imaging perfection. The two critical alignments are:
1. Along the optical axis.
2. Through the center of the pupil, which we will examine later.
Memorize these critical alignments and understand how attacking them with the side to side, up and down, backward and forward technique, will ensure your mastery of them. The side to side, up and down, backward and forward technique is a proactive system of ensuring consistency in your retinal photography. Previously, all other approaches were reactive, as ophthalmic photographers made corrections as a reaction to artifacts. The side to side, up and down, backward and forward technique employs artifacts, as a type of GPS system to guide you to perfecting the two critical alignments. Using a football analogy, the side to side, up and down, backward and forward technique, is like an offense attacking the opposing defense, to dictate the pace and control of the game. The "reactive" method used by others, is like an offense being subservient to the scheme of the opposing offense, rendering that offense meek and at times, ineffectual.
The psychological management of patients new to fluorescein angiography is important. Too often, photographers and technicians ignore the calming of patients as an essential element necessary for success in retinal imaging. Remember, a calm patient is a cooperative patient. The term "angiography" can elicit anxiety. Perhaps these anxious patients have undergone more arduous forms of angiography, like catheterizations for the heart, or pilograms for the kidneys. These uitlize very severe dyes compared to sodium fluorescein.
Simply stating the obvious, that fluorescein dye is largely benign, and that needles and syringes used for fluoresceins are sterile and are for single-use only, can do wonders in calming nervous patients. Nervous patients typically do not process information well because of stress. There is a well-known incidence of transient nausea following fluorescein injection, in the order of 3 to 4%.
I do not recommend mentioning the possibility of transient nausea, as I strongly believe that the incidence of transient nausea would rise due to the power of suggestion.
Let's now look at some general requirements in retinal photography. You need maximally dilated pupils for good results. Wait a minimum of 20 minutes after you've dilated pupils before photographing patients. You will see in many courses, convoluted techniques of setting the camera's ocular for your refractive error, all based on your distance correction. I have but a single recommendation, which is simpler and more effective: if you wear distance glasses, leave them on and set the camera's eyepiece to zero. If you don't wear glasses for distance, fine, still set the ocular to plano.
Leaving the setting at plano and wearing your glasses provides the optimal setup for correct focusing on the camera's reticles (crosshairs). This is all that matters.
If you are young and accomodate, there is a technique to use to train yourself out of accomodating: When you are using your dominant eye for the eyepiece, simultaneously and consciously relax both eyes, and focus your non-dominant eye on a far wall. Of course, your dominant eye must be focused on the eyepiece's crosshairs when you focus the retinal image. Using this method of focusing your non-dominant eye on a far wall, will produce a gradual diminution of your accomodation.
We have to have ways of having patients look in different directions and degrees of gaze, to photograph various parts of the fundus.
There are standardized camera devices used for directing patients' fixation. These are the fixation light and the fixation stick. If a patient has useful vision in the eye not being photographed, you can have the patient follow the fixation light with this eye. If the patient has poor vision in the eye not being photographed, you have no option. You must use the fixation stick.
If using the fixation stick, instruct the patient to, "Please look at the top of the stick."
Patients see the fixation stick the oppposite way that we do. While we see it descending from the top, patients see it rising from the bottom. I recommend the fixation stick as more reliable than the fixation light. It gives a more stable fixation, and does show the relative juxtaposition of pathology in relation to the fovea. This becomes important in cases of macular degeneration.
For patients with poor vision who cannot visualize these devices and you are doing macular studies, instruct the patients to "look at where you think the center of the camera's light is." This is quite effective. With the hearing impaired, you should touch different parts of the patient's face to show the patent what direction that you want the patient to look in. Discuss this plan beforehand with the deaf patient, so you can both expect how this system is going to work.
The topic of focusing has taken on titanic importance in courses in retinal photography, and disproportionately so. Focusing correctly is quite simple, and is the most elementary of your control techniques.
In order to obtain correctly focused images whether those images come from film planes or digital sensors, you must be focusing on the crosshairs in the eyepiece while focusing. If one ignores the reticles (crosshairs) of the camera's ocular while focusing and looks beyond the crosshairs at the fundus only, while the image of the fundus will appear sharp to that photographer at the time, the resulting image on the slide or print will be out of focus. One must consciously be focusing one's shooting eye on the crosshairs, in order for the resulting image to be in focus. It's really that simple: look at the crosshairs while focusing.
Focus comes down to a matter of confidence.
Focusing well should have been mastered in the first few months for the novice retinal photographer. I have seen over the years, many people in my courses who I have recognized as having taken courses on technique for twenty or more years, still obsessing over focusing. This stems from a basic insecurity about one's ability to focus. The reality is this: focusing well is as much a function of self-confidence, as actual tecnique. My advice is this: focus just once per eye with one smooth motion of the focusing knob, and trust that focus.
Then file it, and forget it.
It will be correct. Your initial focus done correctly, will be the best attempt. Don't fall into the trap of racking that focusing knob back and forth, trying to achieve the "perfect" focus. It will only tire you and the patient out. It is a waste of time, and will drive you crazy.
Focusing is really the simplest component of achieving imaging perfection in retinal photography and fluorescein angiography. Far more important than focusing in your quest of image perfection, are your manipulations of the joy stick and vertical control of the camera. Once you have quickly and efficiently achieved focus, then you should concentrate on using the joy stick and vertical wheel, to maintain perfect alignment of the camera. This is where you will find the answer to having perfect angiography. This is where you will perfect your "side to side, up and down, backward and forward" technique.
Misalignment of the camera in relation to the eye will influence the quality of the retinal image, far more than focusing. An extremely important principal to understand, is that once focus is achieved with a given retina, that correct focus will not change, no matter how much the camera is moved in relation to the eye. If the camera is misaligned by movement after attaining good focus, what changes is the quality of illumination, not the focus. One must separate these two entities in one's mind as separate issues to get a clearer understanding:
2. Quality of illumination.
Number two, the quality of illumnation, will be compromised by camera movement after attaining correct focus. A diminution of the quality of illumination will typically be represented by a loss of detail, a haze, a loss of color saturation and artifacts. These features have nothing to do with focus. The focus you have achieved will have remained the same.
Let's try to understand this phenomenon better, of why focus of a retinal image doesn't change with a modification of the camera-to-eye distance. . If you're a photographer on the street, and you focus on a subject three away, and then step back another three feet, then that subject will be out of focus. That's because the objective lens of the general photography system, is the camera's lens. However, in retinal photography, this is not true. In retinal photography, the objective lens of the system, is the patient's lens, and other focusing structures at the front of the eye.
I demonstrate this in my lecture, by showing an eye with focus achieved, and then the same eye with the camera moved back a few millimeters, then six inches from the eye, and then with the camera table racked back all the way, as far as it will go. What these pictures show is that critical focus does not change, but the quality of illumination does in the form of artifacts. I point out that the retinal vasculature, is in the same focus as the first frame, in every frame after moving the camera back. This demonstration convinces skeptics, and makes the point that the most important element of one's technqiue, is to monitor and control the quality of illumination. Focus is just an after thought.
When one changes the quality of illumination with camera movement, it is easy to mistake this as changed focus. The inital reaction to seeing a haze artifact, is "Gee, the focus has changed." All that's happened is that color saturation has been diminished, not critical focus.
It is not focus that's been modified, despite appearances. It is a corruption of the quality of illumination. The quality of illuimination that has been changed by camera movement, must be corrected by movements of the joy stick, not the focusing knob. Once you have achieved focus with the focusing knob, leave the focusing knob alone and use the joy stick and vertical control to regain and maintain the correct alignment of the camera.
Artifacts such as the iris reflection artifact, should be used as a road sign to guide you to finding and maintaining the correct alignments which will guarantee you image perfection. We will examine how to do this after looking at artifacts, in general. Dust and dirt artifacts can be easily cleaned if your lens gets dirty. There are two approaches you can take to cleaning the lens. Choice number one is to call the technician from your camera manufacturer to make an office call, with their fancy little turntables, exotic solutions and q-tips. They will then charge you $200.00 per hour for "labor." This being a five minute job, five minutes equals one hour. Or, you can do the job yourself, using a few things from the camera store, then you can pay yourself the two hundred dollars.
Take a lens cleaning tissue, with some lens cleaning fluid on it and clean the lens with a circular motion. This in itself leaves a residue, so lightly breathe on the lens and before the moisture evaporates, clean the lens again with a dry lens cleaning tissue, and then blow off any residual dust with a rubber bulb blower.
Some will tell you that breathing on a lens will eradicate the lens' coating. I have however, been breathing on the same Carl Zeiss lens I've had in my possession, for the past 38 years without any deleterious effects.
I recommend against using canned air, as these have a gas inside that can expel itself onto your lens in a sticky liquid form, if you hold the can at the wrong angle.
A common artifact occurs from patients' eyelashes. A majority of the time it will be the upper lashes because top lids tend to droop. The first solution is to ask the patient to open wider. If this does not work, then you must retract the eyelid, and here's how it is done. Lightly rest your hand on the patient's head for a stable base, and retract the upper lid with your thumb. This should be done with your non-dominant hand, as your dominant hand should rest on the joy stick to maintain correct alignments. The tighter the "squeezer" the patient is, the more leverage you will need to lift that upper lid. The more leverage you need, the lower on the upper lid you have to contact to retract the lid effectively---so just be careful to keep your thumb out of the way or else this in itself will cause an artifact.
Sometimes patients present with tight lower lids.
If you have to retract the lower lid only, then put your hand into a "thumbs up" configuration, as if celebrating your team's scoring a touchdown, and pull the lower lid down with your thumb.
If both lids have to be retracted, then use what I call the "speculum technique." With your hand still suppported by the patient's head, retract the upper lid with your forefinger and the lower lid with your thumb.
I find that with certain types of nervous patients, lid retraction has a positive psychological effect, as it gives reasurance to them as it relieves them of the responsibility of opening their eyes wider. They tend to relax more because of this. It is like non-verbally conveying to the anxious patient, "You just relax....I'll do all the work...you'll be just fine....you don't have to do anything but relax....."
It is extremely important to constantly scan the perimeter of the frame when viewing the fundus, as this will allow one to become aware of subtle artifacts from one or two lashes that would otherwise go unnoticed. Upon first inspection, some of these images might seem to be acceptable, but even getting one or two lashes out of the way, will make the image, that much better. Always standardize on your technique, of scanning the edges of the frame for imperfection. After some time, this will become second-nature to you.
Let's now look at common artifacts from misalignment, and these will come into play in systematically helping you to achieving image perfection. First, the iris reflection artifact, which results from the camera moving away from the center of the pupil. Misalignment from the center of the pupil results in the camera's light striking the iris. Again, standardize on your technqiue of constantly scanning the perimter of the frame, as some of these iris reflection artifacts will appear as mere slivers and they do tend to blend in with the coloration of the fundus, if they are minute enough.
Both the camera being too far from the eye, and too close to the eye from the ideal position, causes a haze, loss of detail and color saturation. Misaligment from the center of the pupil which causes the iris reflection artifact, and being too far or close to the eye---compromises the two critical alignments which I mentioned before in this order:
1. Through the center of the pupil, corrected by a side to movement of the joy stick accompanied by an up and down movement with the vertical wheel.
2. Along the optical axis, corrected by a backward and forward movement of the joy stick.
Grasp the concepts of these two critical alignments, and truly understand how artifacts manifest themselves when these alignments are off, and how your movements with the joy stick and vertical wheel interact with these artifacts, to systematically reestablish correct alignments. You can approach artifact elimination in a haphazard way (not recommended), or you can perceive and use artifacts as guides to re-finding and maintaining the critical alignments (highly recommended).
A certain amount of theoretical understanding is required, to achieve mastery of underlying technique. The whole key to having perfect underlying technque, is the thoughtful use of the joy stick and vertical wheel, and your brain.
If you have done that very important first step after putting the patient in the chinrest, of obtaining the gross correct distance between the camera to the eye, by focusing the flilament of light on the patient's cornea, then you will have gotten into the ballpark with the correct alignment along the optical axis. The ideal position will only be fractions of an inch from being either too close or too far, if you done this extremely important first step. All one has to do to find the correct position is to engage in a constant backward and forward motion with the joy stick while looking for the deepest color of the fundus. When you have the deepest color saturation, you're there.
This brings us to the crux of how to find and maintain image perfection in fundus photography and fluorescein angiography. It is called the "side to side, up and down, backward and forward drill." I devised this system for myself in the early 1970s, and it is a foolproof method of finding those two critical alignments we've been taking about, very quickly. When one becomes practiced in this method, one can literally find this correct camera positioning in a split second. One can do this so quickly, that one can check camera positioning in between frames of the early phase of angiograms. This means that one can have absolutely perfect frames in every angiogram one does, devoid of artifacts. That means perfect fluoresceins every time.
Here's how it is done:
(1) Move side to side with the joy stick, and at the same time up and down with the vertical wheel.
This allows you to see the iris reflection artifacts on the left and right side, and on the top and bottom as you do your movements. This allows you to judge where the center of the pupil is, and help you to keep the camera light pointed through the center of the pupil.
(2) Then move back and forth with the joy stick while looking for the deepest color of the patient's fundus.
This will allow you to find the correct alignment along the optical axis and to keep it there. This system allows you to find the correct camera position without hesitation. I guarantee that once you become adept at this method, that you will have imaging perfection in fundus photography and fluorescein angiography. This methodology is foolproof and reproducable on a frame to frame, day to day, and angiogram to angiogram basis. Practice this with your color pictures. As you become more proficient with the side to side, up and down, backward and forward technique, you'll be able to graduate to using this for checking your positioning during angiography, in between frames.
Dealing with poor media requires special techniques. The first media problem we'll look at, is cataracts. Successfully shooting around a cataract requires aiming the camera through the clearest part of the patient's lens (cataract). This can be easliy judged by looking at the fundus through the eyepiece, while moving the joy stick into different positions. Quite simply, what you see is what you get.
This will also give us a chance to examine the technique used for stereo fundus photography, as shooting around a cataract on the left and right sides, is identical to the technique used for shooting left and right frames of the stereo pair. Both utilize the iris reflection artifacts as guidelines.
Let's first shoot around the cataract on the left side, and this will allow us to examine how to take that left frame of a stereo pair. From a starting position at the center of the pupil, continue to look at the fundus through the camera's ocular. Slowly move to the left with the joy stick. As you do this, you will gradually see the iris reflection artifact appear on the left side of the frame.
It will sweep to your right as you go further to the left with the joy stick.
When you begin to lose detail of the fundus, stop moving to the left and bring the joy stick to a standstill. I call this point where you start to lose detail, the "point of diminishing returns." At this point after you've stopped moving with the joy stick to the left, begin to progressively move the joy stick backward. Moving back with the joy stick, makes the artifact disappear as if by magic.
As you move back with the joy stick, you will see the iris reflection artifact gradually disappearing in stages. When the artifact completely disappears, then lock the joy stick and take the picture.
What have we done? We've successfully shot around the caratact, and taken our left frame of our stereo pair. Now, simply repeat the procedure to shoot around the right side of the cataract, and take our right frame of the stereo pair. Move to the right with the joy stick until you start to lose visible detail of the fundus. At this point, stop moving to the right with the joy stick, and then pull straight back with the joy stick until the artifact disappears, then take the picture.
Here are some pointers on stereophotography. The farther you move to the left and right sides, the more stereopsis will be induced when viewing the stereo pair slides. Always standardize on taking the left frame first, before the right frame. This will avoid confusion when you view the pictures. If you make a mistake and reverse them, the stereo effect will be reversed. For example, an elevated fundus tumor will look as if it's receding, instead of coming toward you when it is viewed with the slides reversed.
There is a mythology floating out there, that changing the angle of the camera for the taking of each stereo frame, increases stereopis. This is not true. Also, changing the angle will alter the composition of the original juxtapositions of fundal landmarks. We don't want to do this. We want to maintain the integrity of the original frame composition, so that it's a constant in both of the stereo pair pictures.
This brings us to peripheral fundus photography, which I've included as a media problem. I've listed it as a media problem because of the size and shape the pupil takes, when a patient looks up and down or to the sides for peripheral views. The challenge you face are in fact, similar to what you face when shooting around a cataract, and doing stereo fundus photography. The method is also similar in approach. When you focus on a posterior pole, the disc and macula, t's easy because the pupil is nice and round. However, when the patient's gaze is directed peripherally, the pupil becomes eliptical and smaller, therefore, restricting and diminishing the amount of space that you have to fit the camera's light through. Like shooting around a cataract or doing stereophotography, you will be faced with an iris reflection artifact to deal with. You should deal with that artifact in the same manner, by pulling straight back with the joy stick. There are a number of preliminary steps to get into that position first.
Let's go through this technique step by step.
The first thing you should do, is to focus on the posterior pole of the eye while the pupil is nice and round and the focusing is relatively easy. . Remember this principle: The focus that you achieve for the posterior pole, will match any part of the same fundus. This means that once you focus on the posterior pole, you won't have to adjust focus once you reached more peripheral areas of the same eye.
Next, have the patient look in the direction and degree of gaze that's appropriate to the peripheral area you're shooting. Then look around the camera at the patient's external eye and move the camera with the joy stick to place the ring of light partially on the iris, and partially on the pupil, in the direction of the patient's gaze. If the patient is looking to your right, then place the ring of light straddling the pupil and iris, at the3:00 o'clock position for example. In another example, if the patient looks straight up, then place the ring of light partially on the iris and partially on the pupil, at the 12:00 o'clock position.
Then look though the eyepiece. You will see on one side, the iris reflection artifact, and on the other side, the fundus. Now you will do what you've done to eliminate the artifact when shooting around a cataract or when doing stereo photography. You will pull the joy stick straight back, to make the artifact disappear. When the atrifact's gone, then take the picture. Remember, the focus you achieved for the posterior pole will match the focus needed for this area, so you don't have to refine your focus at that peripheral area.
Another media problem is the vitreous hemorrhage, which you will see in diabetic retinopathy. The problem you'll encounter with vitreous bleeds, is focusing through a dense and diffuse bleed, where you won't be able to use retinal landmarks to focus on. It will look like one big, red blur. You might ask, "So if it's a big red blur, why worry about focus, anyway?"
That's because fluorescein will show the retinal vasculature more definitively, than can be seen with ophthalmoscopy or color photography. This might be critical during angiography to localize the source of the bleed.
With vitreous hemorrages, you would like to have what you know is empirically the best focus you can achieve with the eye with the bleed. Here's the workaround for this focusing problem:
Focus on the other eye of the patient, which will have clear media. This bring us to another important principle to know, as it's another principle which will streamline your workflow when doing angiography:
99% of the time, the focus you achieve for one eye of a patient, will match the focus for the other eye of the patient.
Very rarely are vitreous bleeds bilateral, so the other eye should have clear media to focus through.
There is a clear implication here, for when you perform bilateral angiography, which we will cover later: You only have to focus once, on the first eye of a patient that you will be doing bilateral fluorescein angiography on. Remember this important principle.
Here are some other media problems and their solutions. Patients will present that don't dilate well for a variety of reasons. Perhaps the patient is pseudophakic, and the IOL restricts the amount of dilation possible. Maybe it's a glaucoma patient on Pilocarpine. It might be that the patient doesn't dilate well physiologically. Whatever the reason, you must circumvent the loss of light to the fundus due to a small pupil. The answer is simpler than you might think.
The solution here is to turn up the flash intensity one step. This will get more light to the fundus, so an adequately lit image returns to the digital sensor or film plane. I get quite adequate results through 3 and 4 millimeter pupils, by turning the flash up one step.
Any type of contact tonometry will disturb the corneal epithelial cells to cause a blurred image. Defer tonometry during a patient's visit until after fundus photography is done. If a patient has a contact lens exam or laser treatment before you do photography, then the viscous methylcellulose gel used as a buffer on the lens tip to protect the cornea, will cause blurring of the image. What you should do is to irrigate the eye with saline solution and wait a half an a hour before taking pictures.
This brings us to fluorescein angiography. The importance of fluorescein angiography as to its influence on ancillary personnel's role in ophthalmology, cannot be overstated. Before fluorescein angiography came along, we had diverse personnel taking fundus photographs, without any cohesion or revelance to each other. There were nurses, medical photographers and medical assistants, all taking the occasional retinal picture in offices and clinics.
Frankly, before the advent of fluorescein angiography, retinal photography alone wasn't clinically significant enough, to support organizations like JCAHPO and the OPS. Certainly, color retinal photography could not unify the disparate types of personnel doing fundus photography
The sheer diagnostic power of fluorescein angiography changed this ancillary landscape forever. It unified all these different types of workers in a way that no other ophthalmic diagnostic test could. To put it simplistically, the diagnostic ability of fluorescein dye opened up an avenue for ancillary personnel in ophthalmology to become as one, as a more empowered group. Without angiography, eye photographers would not have separated from the Biological Photographers' Association (BPA) to form the OPS. It is within the realm of possibility, that JCAHPO would not have come into existence, without the tremendous clinical importance of fluorescein angiography.
Clinical fluorescein angiography was introduced to ophthalmology in 1961 by two medical students named Novotny & Alvis. It was an inauspicious beginning, as their seminal paper on fluorescein was rejected by all of the major opthalmology journals as believe it or not, not significant enough. Novotny and Alvis published their famous paper in an obscure general medical journal called "Circulation." The rest as the ubiquitous "they" say, is history.
Let's now examine principles and techniques of fluorescein angiography, which can be applied to either film or digital angiography, using our underlying technqiues that we've been discussing. These fundamental principles and techniques will lead to perfect imaging.
By the time you're ready to call the physician to give the dye injection, you will already have taken your color pictures. Remember, the focus you achieve for one eye of the patient will match the other eye, so you only have to focus once, on the primary eye of interest. Do not waste time focusing on the second eye.
Follow this squence. If you're doing a bilateral angiographic study, then start with (for sake of discussion) the right eye. Focus on the right eye, and take your color pictures of it. Then bring the camera in front of the left eye and take your color pictures of it, without focusing on this eye. Your camera is now positioned in front of the left eye, so take your red-free photos of it before moving back to the right eye for the red-free photos of the right eye. When you return to the right eye, you'll end up where you started, ready to start the dye study with the right eye, first.
Your camera will systematically end up in front of your primary eye logistically, if you follow this sequence leading up to the fluorescein injection.
Remember also, that once you've achieved focus, that it will not change. Your job will be to maintain the optimal camera positioning throughout the angiograpic procedure, using the "side to side, up and down, backward and forward" technique. You should monitor the fundus while waiting for the injection, scanning the perimeter of the frame for artifacts and correcting your position if needed. When the physician arrives to inject, this will be the time of the study, when you are most likely to lose control of the procedure. Doctors are trained to talk to patients to reassure them. They'll tell jokes, causing the patient to respond or pull of of the chinrest.
This is when you have to reassert yourself, as the captain of the angiographic team.
It is at this time that you should remind the patient to do exactly what he or she did before. Tell them, "Please keep your chin on the chinrest and your forehead against the bar. Please blink when you want to, but keep your eyes wide open when you're not blinking. Keep looking at the top of the stick, and please don't talk, because when you talk, your mouth opens and closes, making you head and eyes go up and down. Please try to ignore what the doctor's doing...."
After the physician finds a viable vein and is ready to inject, you must be the one to signal for the injection. If the doctor decides when to give the injection, and you're busy tying your shoes at the time, the whole timing of the test might be compromised. So, you must signal for the injection to be begun.
The successful timing of the test depends on your being ready to sequence the angiogram correctly. This can only happen if you are the one to signal for the start of the injection.
It is at this point that you should insert your excitor filter into place. Don't painic! Don't be disturbed that this filter diminshes your view. Depend on your "side to side, up and down, backward and forward" method to maintain the correct alignments, and you can't go wrong.
To repeat, go side to side with the joy stick, and simultaneously up and down with the vertical wheel. This will allow you to gauge where the center of the pupil is. Then move back and forth with the joy stick, to maintain the deepest blue. When you're practiced enough with this technique, you'll be able to, with great confidence, maintain the two critical alignments that ensure perfect imaging during angiography. The speed with which you can complete the side to side, up and down, backward and forward alignment check, will allow you to check your positioning in between frames of the angiogram.
You don't have to visualize the fundus clearly to know where the perfect position is. You need only use your side to side, up and down, backward and forward movement to maintain it, or verify it. All you need to be able to see, are the iris reflection artifacts, and the deepest blue to maintain the correct alignments.
Begin your study at 10 seconds after zero time of injection. This will capture the arterial phase in all cases, because the average arm-to-retina circulation time is 14 seconds. Begin your timing device so that you are aware of the seconds and minutes post injection during the procedure.
It is worthwhile to reiterate the ultimate importance of the "side to side, up and down, backward and forward" drill as the key to your success in obtaining perfect frames. This methodology provides you with a repeatable and reliable technique to quickly seek and obtain the correct critical alignments.
This reproducability of the two correct positions---through the center, and along the optical axis---will ensure that every frame of every study you do will be as perfect as you make it with this method.
In the old days of the 60s and 70s, very inefficient dyes and filters required specialized techniques to maximize fluorescence. We had to employ rapid injections to achieve this. This produced a highly concentrated and short bolus of dye in the patient's bloodstream.
This required using "rapid sequencing," shooting at a rate of one frame per second, to photographically capture the very short bolus of dye in the patient's circulation.
With today's extremely
efficient dyes and filters, using these same techniques would be detrimental, as the amount of fluorescence produced, is too much..
I recommend using slow injections now, to avoid overwhelming choroidal flushes which might actually obscure the detail of pathology.
I started using slow injections in the 1970s when I had a high number of patients with transient nausea following fluorescein injections. The theory was that the extremely concentrated bolus of dye hit the patient's stomach circulation, upsetting their stomachs. Slowing the injections down, was an effort to alleviate patients' nausea.
A slow injection is an injection of 13 to 15 seconds in duration.
This has worked. I've never done any studies but can tell you anecdotally, that my incidence of transient nausea is very low.
A more important byproduct of using slow injections was discovered, however. Slow injections yielded studies that were easier to interpret, due to the more progressive inflow of fluoresecin into patients' retinal and choroidal circulations.
This led to my abandonment of rapid sequencing (shooting the early phase at a rate of one frame per second), because it was no longer necessary to shoot at a frenetic pace to keep up with a short bolus of dye.
I adopted a slower rate of sequencing. I now shoot at a rate of one frame every three or four seconds, which allows me to reach beyond 60 seconds after injection by the 20th frame of my primary eye of interest. This "variable rate" of sequencing, allows a more controlled execution of the angiogram, with a better study that easier to interpret. With the more gradual inflow of dye into the fundal circulations, the detail of pathology has been enhanced, which is critical in macular degeneration.
My recommendation for late phase pictures, is 10 minutes post zero time of timjection. This is adequately late to be able to make critical diagnoses.
I have some general recommendations with regard to the information that should be recognized for the performance of fluorescein angiography. This can eliminate many avoidable errors, unforced errors which can be laid at the feet of carelessness.
One should obtain the essential information needed to execute a given study: Which eye, or both, to study with the angiogram, which eye to start with if it's a bilateral study, which part of the fundus, etc.
Always read the charts for this information.
Beyond that, it would benefit ophthalmic personnel to study the charts of the patient presenting for angiography. There is valuable information there, that would increase your knowledge of retinal disease.
This would lead to a more comprehensive understanding of what the patient's eye condition is, and of how that could influence your peformance and formatting of the study. It would lead ultimately, to a greater understanding in general of how diseases behave angiographically. The more you know, the more valuable an employee you are.
Over time, the habit of chart reading will lead to putting the technician on the same page, so to speak, as the ophthalmologist ordering fluorescein angiography. This can only enhance the whole ophthalmic team's efficiency and workflow.
Using the underlying techniques I've shown you, it is not only a possibility to obtain perfection in your retinal photography and fluorescein angiography, it is a consistent expectation.
These technqiues, particularly the "side to side, up and down, backward and forward" technique, will make your photographic results precise and reliable. If there is anything you do not understand in this tutorial, please do not hesitate to contact me. You can contact me through email at email@example.com or you can contact me on Facebook. When searching for me at Facebook , type in "Scott Genghis Wong" as there are many Scott Wongs out there besides me. You may also find my Facebook page by typing in "Scott Genghis Wong" on Google.