Novel imaging biomarkers in diabetic retinopathy and diabetic macular edema

Abstract

Diabetic retinopathy is one of the major microvascular complications of diabetes mellitus. The most common causes of vision loss in diabetic retinopathy are diabetic macular edema and proliferative diabetic retinopathy. Recent developments in ocular imaging have played a significant role in early diagnosis and management of these complications. Color fundus photography is an imaging modality, which is helpful for screening patients with diabetic eye disease and monitoring its progression as well as response to treatment. Fundus fluorescein angiography (FFA) is a dye-based invasive test to detect subtle neovascularization, look for areas of capillary non-perfusion, diagnose macular ischemia, and differentiate between focal and diffuse capillary bed leak in cases of macular edema. Recent advances in retinal imaging like the introduction of spectral-domain and swept source-based optical coherence tomography (OCT), fundus autofluorescence (FAF), OCT angiography, and ultrawide field imaging and FFA have helped clinicians in the detection of certain biomarkers that can identify disease at an early stage and predict response to treatment in diabetic macular edema. This article will summarize the role of different imaging biomarkers in characterizing diabetic retinopathy and their potential contribution in its management.

Optical Coherence Tomography (Angiography) Biomarkers in the Assessment and Monitoring of Diabetic Macular Edema

“…Currently, OCT is an invaluable and indispensable tool for the monitoring of patients with diabetes, establishes the need for treatment, and formulates prognosis [ 8 ].…”

“…Diabetic macular edema (DME) is identified by the thickening of the retina as a result of excessive fluid accumulation [ 5 ] caused by the breakdown of (BRB) [ 8 ]. The fluid may be extracellular, intracellular, or mixed.…”

“…As a consequence of these morphological changes, the recovery of visual acuity does not parallel the resolution of edema. Therefore, according to another report, CST is not a reliable biomarker to evaluate the prognostic in patients with DME and the attention must be directed to examining the pattern of edema, its extent, and location relative to the inner and outer retina [ 8 ]. Pelosini et al proved that the cross-sectional area between the retinal plexiform layers is a better predictor of visual acuity than macular thickness [ 13 ].…”

“…SND is an important OCT biomarker, but its role as an anatomic and functional prognostic factor needs further investigation [ 8 ].…”

Optical Coherence Tomography Angiography in Intermediate and Late Age-Related Macular Degeneration: Review of Current Technical Aspects and Applications

“…FA is an irreplaceable dye-based invasive diagnostic tool to detect subtle neovascularization, monitor leaks, and compare them with staining and window defects. In the era of photodynamic therapy, FA has been considered the gold standard method for detecting and classifying subtle choroidal neovascularization as classic, occult, or combination subtypes [16,17]. Nowadays, it is still a useful method for the detection of "active" neovascularization and geographic atrophy [16].…”