Smart phones are becoming the modern Swiss army knife for veterinarians, with apps aimed at making the devices everything from mobile formularies to digital medical record-keepers. As the cameras embedded in smart phones evolve, experts say that digital photography is good for more than just gathering evidence of gruesome wounds.
Imaging the equine eye has evolved in the past few years, and veterinarians have lots of options as to how best to evaluate a problem.
“It depends quite a lot on what and where the problem is,” said Dr. Caryn Plummer, assistant professor at the Department of Small Animal Clinical Services at the University of Florida.
If clinicians suspect the issue lies behind or around the eye, rather than inside the eye, an MRI or a CT scan can be the best options to get a closer look. Both those types of imaging are also sometimes useful for looking at the inside of the eye. Plummer advises that MRI is best at analyzing the soft tissues in and around the eye, including the retrobulbar optic nerve and the extraocular muscles. CT is best at checking for fractures or tumors present around or inside the eye.
The method of choice for looking inside the horse’s eye is still ultrasound, although Plummer pointed to a couple of new imaging technologies that aren’t common in the field yet but are becoming part of the repertoire for teaching hospitals.
Optical coherence tomography (OCT) can capture highly detailed, three-dimensional images using near-infared light. The long wavelengths of the light travel into the tissues and scatter, creating the image. Confocal microscopy can also provide three-dimensional images of the eye. This technique adds resolution to a micrograph by adding point illumination and a pinhole to focus a smaller area of the image more intensely than traditional magnification.
Although it can’t take the place of advanced diagnostics, experts say that simpler forms of imaging can also prove useful in keeping up with ophthalmology cases.
“The advent of DSLR photography has increased dramatically the quality and usefulness of ophthalmic photography, as well as its ease,” said Plummer. “Any good DSLR or even a good quality point-and-shoot with a macro function can take really good images.”
Don’t have a professional camera? No problem.
“It is becoming essential to use phone cameras,” said Dr. Dennis Brooks, ophthalmology professor at the University of Florida College of Veterinary Medicine. “They allow the vet to get a good view of the eye—as good as an ophthalmoscope in many cases.”
Brooks is preparing a lecture at this year’s American Association of Equine Practitioners Convention on the use of smartphone cameras and ocular photography. He believes that the quality of today’s phone cameras is very good, but the software that accompanies it leaves something to be desired.
“Vets often encourage photos for tracking progress,” Plummer agreed. “The problem with client photos is that often the quality of the images does not permit useful evaluation.”
There are a variety of apps that can help improve ocular photos.
Some apps, like ProCamera, help by aiding in focusing and exposure, while others, like Slow Shutter Cam, allow for extra controls to slow the autofocus shutter lag to prevent blurring.
There are also a number of attachments and kits for smartphones that turn the phones into temporary ophthalmascopes, allowing the light source to remain on to get an image of the back of the eye.
The EyePhotoDoc is a relatively small clip-on slit-lamp adapter for the iPhone which can detect and automatically adjust exposure and focus.
Larger attachments like the iExaminer from Welch Allyn, have more capabilities—like video as well as still image capture, a self-timer, and even remove sync to patient records—but take some extra time to learn.
What’s Brooks’ best advice for mastering the apps and options? Test them out before taking them into the field—especially the settings that minimize light reflection.
“There is a learning curve,” Brooks said. “They must practice.”
Plummer also cautioned that even high-quality images can’t tell the whole story.
“External photographs are an excellent way of tracking progress, good or bad, of lesions and can give a really good assessment of extent of disease. They cannot, however, replace a thorough ophthalmic examination,” she said.
Plummer believes that’s an especially important point to stress to clients.
“There are so many clinical signs or lesions that can be missed with a two-dimensional photograph that would be apparent on a three-dimensional exam. Also, some lesions are very hard to photograph in a representative way,” she said.
“My stock caveat is that I cannot make a definitive diagnosis without seeing the animal. I can certainly offer some guidance, but without that three-dimensional exam, there will always be some uncertainty.”