For a long time, visualizing and diagnostically documenting the region peripheral to the equator of the retina was very difficult. Previous retinal cameras had certain limitations, and fundus photographers needed a particularly specialized skill set just to adequately montage the area up to and including the equator. When it came to visualizing the peripheral retina anterior to the equator, only those with specialized cameras were successful.

Until the turn of the century, attempts to obtain and record peripheral retinal images were largely ignored by the retina community due to practical and technological limitations. Clinicians who needed information regarding the status of the peripheral retinal vasculature, as in the case of diabetic retinopathy (DR), retinovascular occlusions (RVO), vasculitis or neoplasms, had to rely on head-mounted indirect ophthalmoscopy with some type of video capture device. To perform peripheral retinal angiography, the clinician would wear the indirect ophthalmoscope, have a technician inject the dye into the patient and attempt to document fluorescence (angioscopy). The process was laborious and caused a lot of patient discomfort with suboptimal and minimal results.

In the last decade, we have seen a dramatic shift in the available technology thanks to the launch of widefield imaging (WFI) and and ultra-widefield imaging (UWFI) camera systems, which have allowed us to image more than 80% of the retinal surface area.

THE EVOLUTION OF WIDEFIELD

WFI was introduced in 1999 with the FDA approval of the Optos Optomap Panoramic 200A, the first to allow a field of view up to 200 degrees. At the time, many clinicians considered the technology gimmicky. Some imaging systems required the use of a contact lens to reach the retinal periphery, making it somewhat cumbersome.¹ Slowly but surely, in roads were made that demonstrated its value. By assessing the retina posterior to the equator, we began to learn about the need to institute therapy earlier in some patients.

Several pioneering clinicians,^2-7 including the late Paul Tornambe, MD, began to present compelling data about the critical role of WFI in the management of both DR and RVO patients. In particular, the degree of peripheral retinal ischemia was not only found to be correlative to the severity of the macular ischemia but also with the degree of macular edema. The wide-angle viewing system showed a lot of ischemia and leakage of dye in the periphery that otherwise would have gone unnoticed with traditional imaging technology. In some instances, laser photocoagulation of peripheral ischemic retina resulted in improvement of macular edema. Subsequently, there have been several attempts at treating the peripheral retina based on WFI with laser in order to improve central retinal function and to reduce overall treatment burden. These cases showed that there was merit not only to viewing the peripheral retina, but that doing so can alter the therapeutic approach and management of these patients.

It’s important to note the difference between WFI and UWFI technologies. In 2019, the International Widefield Imaging Study Group published consensus terminology for WFI and UWFI.⁸ The panel reviewed the anatomic location, field of view and perspective provided by these images. They defined WFI as limited to images depicting retinal anatomic features beyond the posterior pole, but posterior to the vortex vein ampulla, in all four quadrants. UWFI was defined as images showing retinal anatomic features anterior to the vortex vein ampullae in all quadrants.

WHY WFI IS SO EFFECTIVE

Current WFI systems don’t rely on standard optics — they use laser diodes to generate the image. Some systems use three separate lasers that generate a false color image of the retina. Others use a broadband, full-spectrum single diode laser to produce the image.

Regardless of the manor in which the system captures the images, this gives modern WFI technology the ability to cut through cataracts (within reason) that would make it difficult for a clinician to otherwise view the peripheral retina through alternate means, such as indirect ophthalmoscopy.

TRAINING

Since the vast majority of retina specialists are very busy in the clinic, they don’t have the luxury of operating WFI systems themselves. Many have to depend on skilled technicians to obtain the images.

Thankfully, WFI systems are an order of magnitude easier to operate than the older, standard fundus camera systems that depend on creating a montage of images. Obtaining good peripheral images with available WFI systems still requires a trained technician and a cooperative patient to ensure that all of the proper fields are captured in the image, though.

Initial training of staff by instructors from the manufacturers of these devices is critical and doesn’t require an extensive amount of training time in comparison to other retinal diagnostic equipment.

SCREENING AND MAKING A PLAN

WFI has facilitated the management of patients with symptoms of posterior vitreous detachment as well as retinal tears or detachments. Many times, either a technician or resident obtains a WFI on a symptomatic patient with floaters and transmits the images to offsite vitreoretinal attendings for assessment and management.

WFI is also utilized to document the location of tears and other retinal lesions. This is a very useful adjunct in medical record compliance, and it does not negate the inclusion of hand-drawn diagrams.

It’s not unusual in a busy retina practice for the technician to obtain a retinal WFI before the clinician even sees the patient. On many occasions when I have been in the OR on a busy surgery day, I have asked a tech to image the retina of a patient referred for floaters and flashes with our widefield system and send the image to my cell phone.

If I see a retinal tear, for example, I will tell my staff to keep the patient until I can come to examine them. If I can rule out a retinal tear and the image does not reveal anything concerning, I can see the patient the next morning. From a practical perspective, this is very useful.

CONCLUSION

With the introduction and increasing adoption of WFI systems in ophthalmology, we are now better able to diagnose, manage and document a variety of peripheral retinal disorders. This is done in association with a much better patient clinic flow due to the ease of image acquisition. OM

REFERENCES

1. Staurenghi G, Viola F, Mainster MA, et al. Scanning laser ophthalmoscopy and angiography with a wide-field contact lens system. Arch Ophthalmol. 2005;123:244-252.
2. Friberg TR, Pandya A, Eller AW. Non-mydriatic panoramic fundus imaging using a non-contact scanning laser-based system. Ophthalmic Surg Lasers Imaging 2003; 34:488-497.
3. Neubauer AS, Kernt,M, Haritoglou C, et al. Nonmydriatic screening for diabetic retinopathy by ultra-widefield scanning laser ophthalmoscopy (optomap). Graefes Arch Clin Exp Ophthalmol 2008; 246:229-235.
4. Yannuzzi LA, Ober MD, Slakter JS, et al. Ophthalmic fundus imaging: today and beyond. Am J Ophthalmol. 2004;137(3):511-524.
5. Friberg TR, Forrester JV. Ultrawide angle (200°+) fluorescein angiography using a modified Optos panoramic200 imaging system. Invest Ophthalmol Vis Sci. 2004;45:E-Abstract 3001-B636.
6. Win PH, Young TA. Optos Panoramic200A fluorescein angiography for proliferative diabetic retinopathy with asteroid hyalosis. Semin Ophthalmol. 2007;22: 67-69.
7. Kaines A, Oliver S, Reddy S, Schwartz SD. Ultrawide angle angiography for the detection and management of diabetic retinopathy. Int Ophthalmol Clin. 2009;49:53-59.
8. Choudhry N, Duker JS, Freund KB, et al. Classification and guidelines for widefield imaging: Recommendations from the International Widefield Imaging Study Group. Ophthalmol Retina. 2019;3:843-849.

About the Author

Sam Mansour, MD, is a clinical professor in the Department of Ophthalmology at The George Washington University School of Medicine & Health Sciences in Washington, D.C. He is also the medical director at the Virginia Retina Center in Warrenton, Va.

Dr. Mansour reported no relevant disclosures.