Nerve and Retinal Changes in Experimental Diabetes
John H. McNeill in Experimental Models of Diabetes, 2018
Human diabetic retinopathy is classified into progressive stages, namely, background (nonproliferative) retinopathy, severe or advanced background (preproliferative) retinopathy, and proliferative retinopathy. Background retinopathy consists of capillary microangiopathy, macular edema and soft exudate, and retinal hemorrhages and exudate. Capillary microangiopathy structurally shows basement membrane thickening, loss of pericytes, microvascular obstruction, permeability changes, and microaneurysms. Cotton wool spots (soft exudate), representing microinfracts of the nerve fiber layer, were once considered an important predictor of proliferative diabetic retinopathy. However, this has not been substantiated.224 Profuse retinal hemorrhages and exudate, venous dilatation and beading, widespread capillary nonperfusion, and intraretinal microvascular abnormalities (IRMA), consisting of telangiectatic vessels shunting blood around areas of nonperfusion, are the characteristic features of preproliferative retinopathy. Patients with these lesions are prone to develop proliferative retinopathy. Proliferative retinopathy is characterized by neovascularization. New blood vessels form on the optic disk, within the retina, on the retinal surface, or inside the vitreous. Neovascularization eventually leads to bleeding, fibrosis, and tractional retinal detachment. An outline of lesions in the various stages of diabetic retinopathy is presented in Figure 6.3.
Diabetes and the Microcirculation
John H. Barker, Gary L. Anderson, Michael D. Menger in Clinically Applied Microcirculation Research, 2019
A proportion of IDDM patients (especially those with hypertension or poor glycemic control) go on to develop more marked background retinopathy, with the development of numerous blot hemorrhages; venous abnormalities, such as beading, reduplication, and looping; variations in arteriolar caliber and arteriolar obstruction leading to “sheathing”; and cotton wool spots, indicating areas of retinal ischemia, which are visible as areas of nonperfusion on fluorescein angiography. At this time, proliferation of microvessels within the substance of the retina leads to intraretinal microvascular abnormalities (IRMAs). Such changes, indicating severe retinal ischemia, are termed preproliferative and herald the development of neovascularization, with proliferation of fragile new capillaries in association with fibrous tissue, growing forward from the surface of the retina (proliferative retinopathy). The presence of these neovascular membranes in association with retraction of the vitreous leads to sight-threatening vitreous hemorrhage from the fragile new vessels. Subsequently, further traction on the retina can cause retinal detachment. Neovascularization of the iris (rubeosis iridis) may lead to the development of a painful and intractable form of glaucoma. IDDM patients become susceptible to the development of proliferative retinopathy after several years of diabetes, with a rapid increase in the incidence of this problem between 10 and 15 years, and thereafter a relatively constant incidence. Around 50% of IDDM patients are affected after 25 years of diabetes,43 and again, this is a less common problem in NIDDM, affecting around 20% of patients.45
Diabetic Retinopathy
Jahangir Moini, Matthew Adams, Anthony LoGalbo in Complications of Diabetes Mellitus, 2022
Severe nonproliferative diabetic retinopathy is the most serious form of this disease. It is characterized by the 4:2:1 rule, which requires at least one of the following factors: ∎ quadrants of diffuse intraretinal hemorrhages and microaneurysms∎ quadrants of venous beading∎ quadrant of intraretinal microvascular abnormalities
Prevalence of Diabetic Eye Diseases in American Indians and Alaska Natives (AI/AN) as Identified by the Indian Health Service’s National Teleophthalmology Program Using Ultrawide Field Imaging (UWFI)
Published in Ophthalmic Epidemiology, 2022
Stephanie Jo Fonda, Sven-Erik Bursell, Drew G. Lewis, Dawn Clary, Dara Shahon, Paolo S. Silva
For the determination of DR and DME severity, previous studies have found that UWFI has perfect agreement with ETDRS photography in 84% of cases and agreement within one level of disease severity in 91% of cases (unweighted κ = 0.79).23 Detailed protocols for evaluating UWF images have been described.17 Graders, who are licensed, certified optometrists supervised by an ophthalmologist, evaluate images on standardized workstations at a centralized reading center at Phoenix Indian Medical Center. Each image is evaluated for distribution of hemorrhages and/or microaneurysms, venous beading, intraretinal microvascular abnormalities and new vessels on the retina. Any DR lesion type is considered predominantly peripheral when more than 50% of it is observed outside the ETDRS standard fields [i.e., ‘predominantly peripheral lesion’ (PPL)].17 UWFI, due to its wide view of the retina, facilitates views of peripheral lesions that is not achievable with the aforementioned NMFP technology. Graders determine whether the presence of PPL increase overall DR severity.
Optical coherence tomography angiography in primary eye care
Published in Clinical and Experimental Optometry, 2021
Alexandra M Coffey, Emily K Hutton, Louise Combe, Pooja Bhindi, Demi Gertig, Paul A Constable
Regardless of the limitations, this technology is rapidly advancing in scanning and software strategies.4 The non‐invasive and relatively inexpensive nature of OCT‐A, compared to fluorescein angiography, enables optometrists to diagnose and triage treatment of various pathologies, such as glaucoma, diabetic retinopathy, age‐related macular degeneration, optic neuropathies and vein occlusion.1‐4 The blood vessel abnormalities most commonly found among diseases are: neovascularisation; non‐perfusion and capillary dropout; and irregular blood vessel shape such as aneurysms, intraretinal microvascular abnormalities and dilated blood vessels.3 Numerous parameters such as VD are used to quantitatively and qualitatively describe the extent of vascular changes as defined in Table 1.1,4 This is a comprehensive review of the clinical application and diagnostic ability of OCT‐A to detect blood flow changes within ocular conditions and to give insight into expected parameter changes.
Relation Between Platelet Reactivity Levels and Diabetic Retinopathy Stage in Patient with Type 2 Diabetes Mellitus by Using Multiplate Whole Blood Aggregometry
Published in Seminars in Ophthalmology, 2021
Işıl Kutlutürk Karagöz, Ali Karagöz, Flora Özkalaycı, Cem Doğan, Gonenc Kocabay, Ahmet Elbay
Diabetic retinopathy (DR) is an important microvascular complication of diabetes mellitus (DM), and it is associated with significant morbidity and mortality. Moreover, it is one of the leading causes of preventable vision loss in adults.1 Poor glycaemic control plays a major role in the development of the microvascular complications,2 leading to neo-angiogenesis, fibrous lesions, microaneurysms, haemorrhages, oedema and intraretinal microvascular abnormalities, which can be determined by ophthalmic examination.3 Although it is well-known that chronic hyperglycaemia could result in DR, and worsen it, the underlying mechanisms remain unclear.4 One of the possible underlying mechanisms of platelet reactivity is due to DM and chronic hyperglycaemia.5 In a study, Boeri et al. demonstrated that the size and number of platelet-fibrin thrombi in the retinal capillaries of patients with DM were likely to be greater than those without DM. It has been indicated that retinal ischemia and the capillary obliteration may be targeted for earlier treatment of DR.6
Related Knowledge Centers
- Diabetes
- Diabetic Retinopathy
- Optic Disc
- Retina
- Blood Vessel
- Neovascularization
- Fluorescein Angiography