The expanding role of widefield imaging in clinical practice

Widefield (WF) imaging has become a transformative technology in retinal diagnostics by providing clinicians with unprecedented insights into both central and peripheral retinal pathology. The older generations of fundus cameras could capture 30 or 50 degrees of field and could expand up to 70 degrees with montaging techniques. Whereas the newer generation of cameras, such as the Optos (Optos Inc, Dunfermline, UK), an ultra-widefield (UWF) imaging system, captures 200 degrees of retina covering approximately 82% of the retinal surface area, in a single click.1 It is quick, non-contact and provides high-resolution images even through small pupils. Apart from fundus photography, other expanded modalities of WF imaging, such as fluorescein angiography (FA), optical coherence tomography (OCT), and OCT angiography (OCTA), are reshaping clinical practice in ophthalmology by enhancing disease detection and patient management across a wide spectrum of disorders.1 Widefield and Ultra-widefield Fundus Photography Traditional retinal imaging restricted analysis to the posterior pole, often missing peripheral lesions integral to the diagnosis and management of several common diseases. WF imaging enables prompt identification of pathologies such as peripheral retinal tears, vascular lesions, or uveitic changes, which are invisible with standard imaging.1 In diabetic retinopathy and retinal vascular occlusions, the detection of peripheral nonperfusion areas has modified disease grading, risk stratification, and treatment approaches—impacting both research and daily patient care.2 In a study, the specificity and sensitivity of WF imaging were 100% with near-perfect diagnostic agreement with indirect ophthalmoscopy for most of the major diseases.2 However, some very peripheral lesions may be missed in UWF imaging. Lin et al.3 found the sensitivity of UWF imaging in detecting peripheral horseshoe tears to be only 50%. Thus, a multimodal approach combining both ophthalmoscopy with scleral depression and WF imaging is preferable. Widefield and Ultra-widefield Fluorescein Angiography The ability to document widespread retinal vasculature, especially the peripheral vasculature with WF and UWF FA, which is mostly unseen in the conventional FA, has advanced our understanding of several vascular as well as inflammatory disorders. In a study comparing the efficacy of UWF FA, it was able to detect peripheral retinal capillary nonperfusion areas and neovascularization in 10% of eyes with diabetic retinopathy that would have been missed by standard FA.4 Furthermore, detection of peripheral ischemic areas may allow targeted retinal laser, which may be less damaging than panretinal photocoagulation in proliferative retinopathy. Adjunctive targeted laser of peripheral ischemic areas, along with anti-vascular endothelial growth factor therapy, is thought to be beneficial in recalcitrant diabetic macular edema.5 Similarly, in retinopathy of prematurity and familial exudative vitreoretinopathy, the UWF FA should be performed to help guide precise laser to the peripheral ischemic retina. It is also invaluable in planning individualized treatment plans for vascular occlusions or vasculitides. Advances with Widefield OCT and OCTA Widefield and UWF OCT—with swept-source platforms—now allow high-resolution sectional imaging of the central and peripheral retinal layers well beyond the vascular arcades. This is particularly valuable in evaluating peripheral degenerations, schisis, or detachments, as well as post-surgical changes.6 Widefield OCTA represents a quantum leap by noninvasively visualizing peripheral vascular plexuses and choroidal flow patterns. It uniquely identifies peripheral nonperfusion and neovascularization, critical in diabetic retinopathy and vein occlusion management, without requiring intravenous dye. The depth-resolved, quantitative nature of this information is superior for monitoring disease progression and therapeutic response.7 The ability to reconstruct three-dimensional images from the WF and UWF OCT makes it useful in the evaluation and monitoring of pathologic myopia.6 However, with a wider field, the peripheral image suffers from lower resolution and motion artifacts, which can occasionally hamper the correct interpretation of the images from the periphery. Clinical Applications and Future Perspectives Widefield imaging has extended its role from specialized tertiary centers into community ophthalmology, diabetic retinopathy screening, pediatric retina, and telemedicine.1 It is indispensable in managing diseases where peripheral retina involvement dictates outcome, including diabetic retinopathy, vein occlusions, uveitis, retinal detachments, and even intraocular tumors.1,5 With the integration of deep learning and artificial intelligence, OCTA has acquired additional insights and predictive capabilities. This advancement has given rise to a new era in biomarker science. With rapid acquisition, increased patient comfort, and ease of integration into EMRs, these modalities can be used with ease in clinical as well as research setups. In summary, widefield imaging, spanning fundus photography, FA, OCT, and OCTA, has fundamentally altered the landscape of retinal practice. As technology further improves, integrated multimodal WF and UWF imaging will become the standard of care.About the authorProf Dhanashree Ratra, MS, DNB, FRCS(Edin), FAICO (Hon), Deputy Director, Dept of Vitreoretinal Diseases, Sankara Nethralaya, Chennai, India. Prof. Ratra is an accomplished vitreoretinal surgeon with extensive expertise in diagnosing and treating retinal disorders. A leading academician and prolific researcher, she has published widely and earned numerous awards and accolades for her contributions to the field. Beyond her clinical and research achievements, she is a sought-after teacher who continues to inspire and guide many followers.