What do people with diabetes fear most? Blindness. When they attend for screening, what do they want to know? Whether they will need treatment and whether they will lose their vision.
Currently, we know the population-level risk factors for the development and progression of diabetic retinopathy but not their relevance for individual patients. There have been a number of advances in the treatment of diabetic macular oedema (DMO) involving intravitreal injections of either steroids or anti-vascular endothelial growth factor agents. These treatments have shown a benefit over conventional laser treatment in that, for the first time, lost vision can be restored (Stewart, 2014). However, we are unable to predict which individuals will gain or lose vision.
The authors of the article under review state the importance of identifying reliable biomarkers of current and future vision. This will not only assist in counselling patients undergoing treatment but may also allow healthcare cost savings by identifying those people who will benefit from treatment. Perhaps more importantly, identification of the pathophysiological changes preceding visual loss will inform our understanding of the disease process and potential new treatments.
Whilst diabetic retinopathy has been regarded as a process largely involving damage to the various components of the retinal capillary bed secondary to hyperglycaemia, it has long been known that changes in the neuroretina may precede clinically visible features in the retina. This has led to current interest in the role of neuroprotective agents.
Optical coherence tomography (OCT) has revolutionised the management of DMO by allowing retinal thickness to be objectively quantified, rather than relying on a subjective clinical definition such as “clinically significant macular oedema”. In particular, spectral-domain OCT has allowed high-resolution visualisation of the individual layers of the retina.
In the study summarised alongside, the authors identified a novel surrogate marker that was able to predict visual acuity (VA) in people with current or resolved DMO. They termed this marker “disorganisation of the retinal inner layers” (DRIL). Eighty eyes in 58 individuals were studied. DRIL appeared to be highly correlated with VA in people with current or resolved DMO and were more robustly and consistently associated with VA than any of the other recognised OCT features, including central retinal thickness, the current parameter used for treatment.
This was a small trial and the results need to be validated in larger longitudinal studies; however, the results are encouraging and pivotal in taking the science forward towards better-informed patient education and advice and patient-specific therapies.
To read the article summaries, please download the PDF
Amid accumulating evidence of benefits with new diabetes drugs, Vinod Patel asks whether the costs can be justified.
9 Nov 2023