Evans blue staining to detect deep blood vessels in peripheral retina for observing retinal pathology in early-stage diabetic rats

AIM: To observe and compare the statistical significance of superficial and deep vascular leakage in the pathological changes of the diabetic rats retina after the Evans blue(EB) perfusion, and utilize the modified whole-retina spreading method to make the slides while protecting the periphery of the retina. METHODS: The Sprague-Dawley(SD) rats were randomly divided into 6 groups. Each group named as the normal groups for 4, 8, and 12 wk and the diabetic groups for 4, 8, and 12 wk. The EB was injected into the cardiovascular system of the rats at the different time points. The retina of each group was obtained for observation.RESULTS: The superficial vascular leakage was found in all 6 groups. The size of leakage area of superficial retinal blood vessels was(0.54±0.23)%,(0.65±0.11)%,and(0.58±0.10)% in normal group. No notable leakage was found in the deep blood vessels [(0.03±0.04)%,(0.03±0.05)%, and(0.03±0.05)%]. The deep retinal vascular leakage was found in the peripheral retina of diabetic rats. The size of leakage area of superficial retinal blood vessels in diabetic group were(0.53±0.22)%,(0.69±0.16)%, and(0.52±0.11)%. The leakage areas of deep blood vessels were(0.54±0.50)%,(1.42±0.16)%, and(1.80±0.07)% at 4, 8, and 12 wk, respectively. There was a statistically difference of the leakage area between the 8 th week and the 4 th week of diabetes group(P=0.003). The statistically significant difference between the diabetes and the control groups was noted at 4 wk and 8 wk(P<0.001).CONCLUSION: The main retinal pathological changes of early-stage diabetic rats are the vascular leakage of the periphery of deep retina. Diabetic rats modeled after 8 wk have semi-quantitative statistical difference compared with the normal rats, thus early intervention treatment research can start at this time point.

Therapeutic potential of iron chelators in retinal vascular diseases

Iron is one of the necessary metal elements in the human body.There are numerous factors that control the balance of iron metabolism,and its storage and transportation mechanisms are intricate.As one of the most energyintensive tissues in the body,the retina is susceptible to iron imbalance.The occurrence of iron overload in the retina leads to the generation of a significant quantity of reactive oxygen species.This will aggravate local oxidative stress and inflammatory reactions and even lead to ferroptosis,eventually resulting in retinal dysfunction.The blood-retinaretinal barrier is eventually harmed by oxidative stress and elevated inflammation,which are characteristics of retinal vascular disorders.The pathophysiology of retinal vascular disorders may be significantly influenced by iron.Recently,iron-chelating agents have been found to have antioxidative and anti-inflammatory actions in addition to iron chelating.Therefore,iron neutralization is considered to be a new and potentially useful therapeutic strategy.This article reviews the iron overload in retinal vascular diseases and discusses the therapeutic potential of iron-chelating agents.

The role of neuroinfammation in glaucoma

Glaucoma is a chronic neurodegener-ative disorder characterized by progressive damage and loss of retinal ganglion cells （RGCs）. It is considered one of the leading causes of irreversible blindness in the older population. There are estimates that glaucoma will affect 80 million individuals worldwide by the end of this de-cade, and yet we are still not able to identify the signals and the mechanisms that trigger this neurodegenerative disease. Various hypotheses have been generated to ad-dress the causes of the progressive RGC death that char-acterizes the disease. Age and increased intraocular pres-sure （IOP） have been established as the main risk factors for the development of glaucoma. Recent studies have identifed additional factors that play a role in the patho-genesis of this complex multifactorial disease, including infammation, oxidative stress, vascular dysregulation, disrupted axonal transport of neurotrophic factors, and the release of neurotoxic agents such as glutamate, nitric oxide and free radicals. The currently approved therapies for glaucoma that seek to reduce IOP, including medica-tions, laser treatment, and surgery, are unable to reliably stop RGC loss and functional impairment. Considering the signifcant personal, medical and socio-economic im-pacts of glaucoma as a leading cause of blindness, there is a pressing need for new innovative treatment strategies. Here we focus on the role of neuroinfammation in glau-coma and the opportunities that new fndings in this area have for the development of future therapeutics.