The most recent issue of JMTM included an editorial on clinical photography. One keen reader, Dr John Davis, a Junior Opthalmic Resident at JIPMER has compiled an interesting “how to” article summarising some practical tips.
While the debate on the ethics and legalities of taking clinical photos remains a debated topic, this guide is aimed at increasing the quality of the images, if you do decide to take them.
Guest news post below.
Application of Smartphone Devices in Ophthalmic Photography
Dr John Davis
We live in an age where technology is both advancing fast and becoming more accessible. Smartphones and Mobile Devices is one area where this rapid growth is very visible. The availability of cheaper, faster and more capable mobile computing devices has led to a lot of innovations in every field where it can be applied. Smartphones are becoming ubiquitous, with every Tom, Dick and Harry owning one.
The camera is one of the main features of a smartphone today. Compared to the early days of camera mobiles, smartphone cameras now are quite good for all practical purposes. Also, the device being always available and portable is more important than having the most advanced camera.
While the built – in camera Apps are quite adequate for most people, it would be wise to download and install a more advanced camera software for your mobile to allow better control of the lighting, focus, exposure, white balance and other settings.
I would suggest Camera FV-5, ProCapture, Shot Control for Android. Similar software are available for iPhone and Windows mobile and even Nokia(Symbian and Java) too.
Always remember to have adequate lighting (preferably daylight), plain good-contrast background, good focus on the area of interest. Make sure to frame the picture including background, capture at maximum resolution, and take multiple photographs. Use zoom sparingly, especially digital zoom. Go closer to the subject instead of using digital zoom.
When taking before-after photographs, try to take with the same background and lighting. Same clothing and hairstyle would also help, if feasible. Make sure the zoom and other parameters, including exposure and ISO, is also same.
Later, editing can be done to crop out unwanted parts, adjust the resolution and filesize, adjust the background color and delete unwanted photos. Never worry about wasting space on digital photos. It is not like film where every snap counts.
External eye photography
The first and obvious role of an ophthalmologist’s camera/mobile is to take clinical photographs of interesting cases. This might be for future reference, for getting a second opinion, to visually see the change on follow-up, to convince the patient of the pathology, for tele-ophthalmology purposes, for measurements, for legal documentation, etc among other things.
Make sure to take photos with adequate lighting and with good focus(most apps have touch-to-focus an area of interest). Change the focus to Macro mode for taking close up photographs. ISO settings and exposure settings help if you know what you are doing.
Keeping the camera steady is important, and resting your hands against a solid object would help keep it steady. Lighting should be from behind the camera in most cases. An on-screen histogram can show information about bright and dark areas(available in some apps) and make sure to take photos from different angles
Slit Lamp photography
One of the most important, extremely useful, but expensive equipment a young ophthalmologist needs is the slit lamp biomicroscope. It has innumerable uses in ophthalmology, and it is always better to get the best in terms of the optics and capacity for add-ons. If there was a way to get the digital imaging capability of higher end slit lamp microscopes without burning a hole in your bank account, it would be awesome, wouldn’t it ?
Well, many of us might have tried to take photographs through the eye-piece of the slit lamp or other microscopes and partially succeeded, getting good photos once in a while. This works quite well for taking an interesting photo at short notice. We just have to make sure to hold the mobile/camera steady and centered. Adjust the camera forward and backward till the entire field is filled with the image. Turn off the flash, reduce the exposure, touch-to-focus, wait for the white-balance and auto-ISO to adjust to the light and only then click the photo.
To make the job easier, several people have made slit-lamp adaptors for mobiles which is basically a piece of plastic to hold the mobile steady and at the correct distance. You can make your own using discarded bottle caps of the correct size to fit the slit-lamp eyepiece. Readymade ones are also available for sale. For those who know about 3D printing, note that LVPEI has designed and released some adaptor designs on Thingiverse for download and 3d-printing(which is cool, if you have access to a 3D printer).
Once the mobile is in the slit lamp adaptor, you can much more conveniently adjust the advanced camera settings like ISO, exposure and light metering. You can adjust the brightness in the slit lamp, move it forward and backward to focus, all while looking at the image on the phone screen(no need to look through the eyepiece yourself). Try out all combinations of settings and different magnifications and even take videos where necessary.
You can take photographs of lesions on diffuse illumination, slit beam illumination, maybe even specular reflection if your slit lamp and camera are good enough. Cataract grading can be photographically documented, hypopyon, hyphaema can be measured and documented. Corneal ulcers can be followed up with successive photographs. Applanation mires can be photographed. Gonioscopy can be photographed and videographed. A good collection of gonioscopy videos is available on gonioscopy.org . Add your videos to the collection. Fundus examination with 90D or 78D lens can also be photo or videographed.
The same principles can be applied to take photos or videos through all the instruments with an eyepiece, taking care not to damage the lenses. Photographs can be taken through manual keratometers, operating microscope, and some ophthalmoscopes like panoptic which have a large eyepiece.
Indirect fundus photography
Next, let us see what we will need to take a fundus photo without a slit lamp and 90D. We will need ONLY a 20D lens, steady hands, and obviously the mobile/camera.
Just like doing indirect ophthalmoscopy, you can use the mobile as the light source and eyepiece(headset) and focus using the 20D lens. For getting the co-axial illumination, one technique is to turn on the LED flash of the phone and then using the camera. In Samsung phones, just turn on “assistive light”, and then use the camera. Another technique is to use some advanced camera software which allows you to keep the LED “ON” while focusing the photo(but not the default camera app). Yet another technique is to simply take a video with the flash “ON”. The video mode keeps the flash “ON” continuously and you can capture a view of all quadrants in one shot. But the clarity in video may be less than the best, and extracting the photos would mean taking screenshots or frames using a separate software like VLC.
To make the process of indirect fundus photography easier and more reliable, Robert Chang et al developed a plastic adaptor to hold the 20D lens at the correct distance in front of the mobile. They have named it eyeGo and expect to release it as a 3D printable format just like GANANT from LVPEI did for the slit lamp adaptors.
Direct fundus photography
There are now portable fundus cameras in the cost range of Rs 4 lakhs, which work just like a direct ophthalmoscope. The Welch Allyn Panoptic ophthalmoscope has an extra add-on to fix an iPhone onto the eyepiece to take photos. We could do the same for any mobile or camera by making sure it fits snugly onto the eyepiece. It might be possible to fix a mobile/camera to a regular direct ophthalmoscope too, but the eyepiece is so small that it has to be centered well to get a usable image.
3 D photography
With the advent of cheaper 3D TVs, 3D mobiles, 3D laptops and other 3D viewing techniques, stereo-photography is another technique which is becoming feasible and practically usable. Stereo photographs are useful not only in fundus photography, but also slit lamp photographs, eye surgery videos and even clinical photographs. It is very much possible to take 3D photographs even with a regular smartphone camera. You just need the right software and technique.
For clinical photographs, you can use the Inverse Panorama(Object movie) camera mode which is there in the default camera app in Micromax and Xolo phones. Basically, it takes a video while you revolve your camera around an object/subject. And when you play it you can scroll side to side giving you a perception of depth. The files are saved as MPO files which is a standard 3D photo format playable on 3D TVs.
Another software which does essentially the same thing is “Easy 3D Camera”, but you have to make it click each individual photo after moving the mobile by few degrees at a time. This software also has the option to view the photo in various pseudo-3D modes as well as using Red-Blue Glasses if you have them. Try the wiggle mode – it is a simple yet effective pseudo-3D mode for all practical purposes. Google for wigglegrams if you want to see examples. There are several other software for taking 3D photos from regular smartphones, most of which take only 2 images (left and right eye views)
Slit lamp photography in 3D is more difficult, but basically, if the subject can stay still, using the 3D photo software, take the left image through the left eyepiece and the right image through the right. The additional depth perception will definitely help in diagnosis over a standard 2D photograph.
3D fundus photography is supported by many desktop fundus cameras. Some have simultaneous left and right image capture, but most need you to take a left image first, followed by the right image after moving the camera around 4 mm to the other end of the pupil. Doing the same in mobile photography appears to be very difficult at present.
Many of you might have heard of eye surgeries being shown in 3D in special conferences, or even in your own institute if you are lucky. 3D eye surgery videos are also available on youtube. Just go to Youtube and, after a search, select Filters > Features – 3D. There are many methods to view the 3D, of which I would suggest Red-Blue Glasses if you have them, or Mirror split mode if you have a small mirror. Parallel or cross eyed if you have that much accommodation power. If you do have a 3D TV or 3D laptop, full color proper 3D is available to you.
That is all for now. Do send me your comments and ideas at johndavis AT JIPMER (D0T) net.