As recommended by Christopher Mody, ophthalmic scientist and clinical director at Heidelberg Engineering
It is important to remember that diabetic retinopathy is an ocular manifestation of a systemic disease. Microvascular change implies an increased risk of other systemic conditions such as nephropathy, neuropathy, coronary artery disease, stroke and peripheral artery disease. Early detection of microvascular complications is instrumental in effective management of diabetes.
The Role of Multimodal Imaging in Early Detection and Management
In addition to gathering a detailed medical history, undertaking a detailed ocular examination and recording best correct visual acuity are essential steps. Fundus documentation is of primary importance and OCT assessment has become the standard of care in an effective multimodal imaging protocol for diabetic retinopathy. Angiographic assessment of retinal microvascular structure is also fundamental.
Fundus Photography and OCT Assessment
With the acquisition of two fundus photographs centered on the macula and optic nerve head, lesions can be identified and support the detection of sight-threatening retinopathy with a sensitivity and specificity of 96% and 98%, respectively. However, monitoring of progression and therapeutic response may require a more detailed imaging protocol.
“My main piece of advice for clinicians is to prioritize the imaging process. Virtual assessment of patients via telemedicine is now commonplace, but this is only as effective as the quality of images acquired.”– Chris Mody
Angiographic Techniques: From FA to OCTA
While wide and ultra-widefield fundus imaging provide visualization of retinal ischemia and neovascularization in the peripher, it does not bring anything new to our understanding of the disease. The use of a confocal scanning laser ophthalmoscope (cSLO) reduces unwanted light scatter and increases image contrast and resolution. Multi-spectral fundus imaging can provide additional diagnostic insight and can be combined with simultaneous OCT acquisition to pinpoint pathology.
Fluorescein angiography (FA) has long been the gold standard of care and is used to identify ischemic maculopathy, confluent capillary non-perfusion and evidence of retinal neovascularization. However, in recent years non-invasive OCT angiography (OCTA), has largely replaced the use of FA in the assessment of ischemic maculopathy. Ultra-widefield OCTA permits the assessment of peripheral microvascular change which may be beneficial in the assessment of proliferative retinopathy.
AI Analytics for Enhanced Screening Accuracy
Probably the most significant advance in diabetic retinopathy screening has been the development of AI analytics. Identifying evidence of intra-retinal fluid (IRF) is key to both initiating treatment and monitoring therapeutic response. Qualitative assessment of OCT images for the presence of IRF and increased central macula thickness can support early detection.
The implementation of AI can potentially reduce costs, improve consistency and increase availability of retinal screening. Fundus and OCT images are anonymized, encrypted and sent to the AI application provider. Analyzed results are returned and displayed in the patient record for evaluation.
Importance of Patient Communication
Effective communication plays a fundamental part in acquiring high-quality images. Explaining the benefits, giving clear instructions, engaging patients to cooperate and outlining what to expect during the exam helps to improve compliance and in turn image quality.
Impact of Corneal Changes on Retinal Imaging
Glycemic control significantly impacts corneal health and can result in increased corneal thickness, tear film instability and change in the crystalline lens. Changes in the cornea can have a detrimental impact on retinal images. Utilizing ocular lubricants and avoiding contact eye examination techniques improves image quality.
Overcoming Media Opacity in Retinal Imaging with cSLO Technology
Cataract is one of the common causes of poor retinal images. cSLO imaging can also minimize the impact of media opacity. The use of monochromatic fundus imaging such as infrared or green reflectance can also mitigate these effects. OCT imaging is less affected by media opacity and live eye tracking further reduces noise and improves image quality.
