Systemic considerations in the management of diabetic retinopathy

Protective Effects of Bioactive Compound-Derived Nanoparticle Against Diabetic Retinopathy Through the Modulation of the NF-κB Signaling Pathway

Diabetic retinopathy is a prevalent and severe microvascular complication of diabetes, often causing visual impairment and blindness in adults. This condition significantly impacts the quality of life for many diabetes patients worldwide. Berberine (BBR), a bioactive compound known for its effects on blood glucose levels, has shown promise in managing diabetic complications. However, the exact mechanism of how BBR influences the development of diabetic retinopathy remains unclear. In this study, we focused on synthesizing a formulation derived from BBR and assessing its protective effects against diabetic retinopathy. The formulation was created using a green synthesis method and thoroughly characterized. In vitro studies demonstrated the antioxidant activity of the formulation against 2,2-diphenyl-1-picryl-hydrazyl-hydrate. We also examined the NF-κB signaling pathway at a molecular level using real-time polymerase chain reaction. To mimic diabetic retinopathy in a controlled setting, a diabetic rat model was established through streptozotocin injection. The rats were divided into normal, diabetic, and treatment groups. The treatment group received the formulated treatment via intragastric administration for several weeks, while the other groups received normal saline. Evaluation of histopathological characteristics and microstructural changes in the retina using hematoxylin and eosin staining revealed that the bioactive compound-derived nanoparticle exhibited favorable biological, chemical, and physical properties. Treatment with the formulation effectively reduced oxidative stress induced by diabetes and inhibited the NF-κB signaling pathway in the diabetic rat model. Under high glucose conditions, oxidative stress was heightened, leading to mitochondria-dependent cell apoptosis in Müller cells via the activation of the NF-κB signaling pathway. The bioactive compound-derived formulation counteracted these effects by decreasing IκB phosphorylation, preventing NF-κB nuclear translocation, and deactivating the NF-κB signaling pathway. Furthermore, treatment with the bioactive compound-derived formulation mitigated retinal micro- and ultrastructural changes associated with diabetic retinopathy. These results indicate that the formulation protects against diabetic retinopathy by suppressing oxidative stress, reducing cell apoptosis, and deactivating the NF-κB signaling pathway. This suggests that the bioactive compound-derived formulation could be a promising therapeutic option for diabetic retinopathy.

Relationship Between Disease and Treatment Factors in Diabetes With Vision Difficulty: A Cross-Sectional, Population-Based Analysis

BACKGROUND AND OBJECTIVE

Relationships between disease and treatment factors of diabetes and vision difficulty remain largely unknown. This study investigated the relationship between disease and treatment factors in diabetes and participants' self-reported vision difficulty.

PATIENTS AND METHODS

This was a cross-sectional, population-based analysis. Data from the National Health Interview Survey was used and analyzed through univariable and multivariable logistic regression.

RESULTS

From the 29,464 included participants, logistic regression showed increased odds of self-reported vision difficulty among participants with diabetes (odds ratio [OR] = 2.14, P < 0.001), prediabetes (OR = 1.95, P < 0.001), or gestational diabetes (OR = 1.54, P < 0.001) compared to participants without diabetes. Those who reported having diabetes for more than a year had higher odds of vision difficulty (OR = 1.97, P = 0.02), as did those who were taking insulin (OR = 1.62, P < 0.001), those who had taken less insulin to save money within the past year (OR = 1.87, P = 0.01), and those who reported experiencing diabetes-related stress (OR = 2.14, P < 0.001).

CONCLUSIONS

Duration of diabetes, diabetes-related stress, and taking less insulin than recommended to save money were associated with vision difficulty. [Ophthalmic Surg Lasers Imaging Retina 2024;55:142-153.].

Protamine as a barrier against the angiogenic effect of insulin: a possible role of apelin

Insulin is proved to have angiogenic ability thereby may worsen the diabetic retinopathy (DR) progression. Insulin also triggers the expression of endogenous angiogenic peptide, apelin. Since protamine was introduced as an inhibitor of the apelin receptor, we hypothesized that use of protaminated insulin instead of non-protaminated insulin can decrease the negative role of insulin in progression of DR. Firstly, the incidence of DR was compared among three diabetic patient groups: an oral medication, non-protaminated insulin, and protaminated insulin (PIns). Proliferation and migration rate of HUVECs was measured after insulin, apelin, and protamine exposure. In clinical study, the chance of developing DR was 8.5 and 4.1 times higher in insulin group and PIns groups compared with oral group respectively. Insulin group had a chance of 9.5-folds of non-proliferative DR compared to oral group. However, the difference of non-proliferative DR between PIns and oral group wasn't significant. In-vitro tests showed that concomitant use of insulin and apelin increases viability and migratory potential of HUVECs. However, protamine could reverse this effect. Protamine present in some insulins might show a promising protective role against diabetic retinopathy. Thus, protaminated insulins may be preferable in the treatment of diabetes.

New Insights on Dietary Polyphenols for the Management of Oxidative Stress and Neuroinflammation in Diabetic Retinopathy

Diabetic retinopathy (DR) is a neurodegenerative and vascular pathology that is considered one of the leading causes of blindness worldwide, resulting from complications of advanced diabetes mellitus (DM). Current therapies consist of protocols aiming to alleviate the existing clinical signs associated with microvascular alterations limited to the advanced disease stages. In response to the low resolution and limitations of the DR treatment, there is an urgent need to develop more effective alternative therapies to optimize glycemic, vascular, and neuronal parameters, including the reduction in the cellular damage promoted by inflammation and oxidative stress. Recent evidence has shown that dietary polyphenols reduce oxidative and inflammatory parameters of various diseases by modulating multiple cell signaling pathways and gene expression, contributing to the improvement of several chronic diseases, including metabolic and neurodegenerative diseases. However, despite the growing evidence for the bioactivities of phenolic compounds, there is still a lack of data, especially from human studies, on the therapeutic potential of these substances. This review aims to comprehensively describe and clarify the effects of dietary phenolic compounds on the pathophysiological mechanisms involved in DR, especially those of oxidative and inflammatory nature, through evidence from experimental studies. Finally, the review highlights the potential of dietary phenolic compounds as a prophylactic and therapeutic strategy and the need for further clinical studies approaching the efficacy of these substances in DR management.

Spontaneous Resolution of Tractional Retinal Detachment in a Type II Diabetic Patient

A 43 years old male with diabetes type II was under treatment for diabetic retinopathy with extramacular tractional retinal detachment (TRD) in the left eye OS. During the follow-up visit, the patient had a drop in vision from 20/25 to 20/60. The TRD was found to have progressed to involve the macula and was threatening the fovea; therefore, vitrectomy was thought to be inevitable. Meanwhile, the patient adopted exercise and tight glycemic control, and during the preoperative evaluation of three months duration, we observed resolution of traction and return of visual acuity to baseline (20/20). In conclusion, spontaneous resolution of TRD is extremely rare. If it occurs, the patient may be spared from undergoing a vitrectomy.

Diabetic retinopathy screenings in West Virginia: an assessment of teleophthalmology implementation

BACKGROUND

The prevalence of diabetes in the state of West Virginia (WV) is amongst the highest in the United States, making diabetic retinopathy (DR) and diabetic macular edema (DME) a major epidemiological concern within the state. Several challenges exist regarding access to eye care specialists for DR screening in this rural population. A statewide teleophthalmology program has been implemented. We analyzed real-world data acquired via these systems to explore the concordance between image findings and subsequent comprehensive eye exams and explore the impact of age on image gradeability and patient distance from the West Virginia University (WVU) Eye Institute on follow-up.

METHODS

Nonmydriatic fundus images of diabetic eyes acquired at primary care clinics throughout WV were reviewed by retina specialists at the WVU Eye Institute. Analysis included the concordance between image interpretations and dilated examination findings, hemoglobin A1c (HbA1c) levels and DR presence, image gradeability and patient age, and distance from the WVU Eye Institute and follow-up compliance.

RESULTS

From the 5,512 fundus images attempted, we found that 4,267 (77.41%) were deemed gradable.  Out of the 289 patients whose image results suggested DR, 152 patients (52.6%) followed up with comprehensive eye exams-finding 101 of these patients to truly have DR/DME and allowing us to determine a positive predictive value of 66.4%. Patients within the HbA1c range of 9.1-14.0% demonstrated significantly greater prevalence of DR/DME (p < 0.01).  We also found a statistically significant decrease in image gradeability with increased age.  When considering distance from the WVU Eye Institute, it was found that patients who resided within 25 miles demonstrated significantly greater compliance to follow-up (60% versus 43%, p < 0.01).

CONCLUSIONS

The statewide implementation of a telemedicine program intended to tackle the growing burden of DR in WV appears to successfully bring concerning patient cases to the forefront of provider attention.  Teleophthalmology addresses the unique rural challenges of WV, but there is suboptimal compliance to essential follow-up with comprehensive eye exams. Obstacles remain to be addressed if these systems are to effectively improve outcomes in DR/DME patients and diabetic patients at risk of developing these sight-threatening pathologies.

Investigation of the correlation between diabetic retinopathy and prevalent and incident migraine in a national cohort study

Migraine is a disease characterized by cerebral vasodilation. While diabetes has previously been associated with a lower risk of migraine, it is not known if diabetic retinopathy (DR), a retinal peripheral vascular occlusive disease, is a potential biomarker of protection against migraine. Therefore, we aimed to examine diabetic retinopathy as a marker of prevalent and 5-year incident migraine. In a national cohort, we compared patients with diabetes attending DR screening from The Danish National Registry of Diabetic Retinopathy (cases, n = 205,970) to an age- and gender-matched group of patients without diabetes (controls, n = 1,003,170). In the cross-sectional study, a multivariable model demonstrated a lower prevalence of migraine among cases compared with controls (OR 0.83, 95% CI 0.81–0.85), with a lower risk in cases with DR than in those without (OR 0.69, 95% CI 0.65–0.72). In the prospective study, a lower risk of incident migraine was found in a multivariable model in cases (HR 0.76, 95% CI 0.70–0.82), but this did not depend upon the presence of DR. To conclude, in a national study of more than 1.2 million people, patients screened for DR had a lower risk of present migraine, but DR was not a protective marker of incident migraine.

Diabetic macular ischaemia- a new therapeutic target?

Diabetic macular ischaemia (DMI) is traditionally defined and graded based on the angiographic evidence of an enlarged and irregular foveal avascular zone. However, these anatomical changes are not surrogate markers for visual impairment. We postulate that there are vascular phenotypes of DMI based on the relative perfusion deficits of various retinal capillary plexuses and choriocapillaris. This review highlights several mechanistic pathways, including the role of hypoxia and the complex relation between neurons, glia, and microvasculature. The current animal models are reviewed, with shortcomings noted. Therefore, utilising the advancing technology of optical coherence tomography angiography (OCTA) to identify the reversible DMI phenotypes may be the key to successful therapeutic interventions for DMI. However, there is a need to standardise the nomenclature of OCTA perfusion status. Visual acuity is not an ideal endpoint for DMI clinical trials. New trial endpoints that represent disease progression need to be developed before irreversible vision loss in patients with DMI. Natural history studies are required to determine the course of each vascular and neuronal parameter to define the DMI phenotypes. These DMI phenotypes may also partly explain the development and recurrence of diabetic macular oedema. It is also currently unclear where and how DMI fits into the diabetic retinopathy severity scales, further highlighting the need to better define the progression of diabetic retinopathy and DMI based on both multimodal imaging and visual function. Finally, we discuss a complete set of proposed therapeutic pathways for DMI, including cell-based therapies that may provide restorative potential.

Long-term prediction models for vision-threatening diabetic retinopathy using medical features from data warehouse

We sought to evaluate the performance of machine learning prediction models for identifying vision-threatening diabetic retinopathy (VTDR) in patients with type 2 diabetes mellitus using only medical data from data warehouse. This is a multicenter electronic medical records review study. Patients with type 2 diabetes screened for diabetic retinopathy and followed-up for 10 years were included from six referral hospitals sharing same electronic medical record system (n = 9,102). Patient demographics, laboratory results, visual acuities (VAs), and occurrence of VTDR were collected. Prediction models for VTDR were developed using machine learning models. F1 score, accuracy, specificity, and area under the receiver operating characteristic curve (AUC) were analyzed. Machine learning models revealed F1 score, accuracy, specificity, and AUC values of up 0.89, 0.89.0.95, and 0.96 during training. The trained models predicted the occurrence of VTDR at 10-year with F1 score, accuracy, and specificity up to 0.81, 0.70, and 0.66, respectively, on test set. Important predictors included baseline VA, duration of diabetes treatment, serum level of glycated hemoglobin and creatinine, estimated glomerular filtration rate and blood pressure. The models could predict the long-term occurrence of VTDR with fair performance. Although there might be limitation due to lack of funduscopic findings, prediction models trained using medical data can facilitate proper referral of subjects at high risk for VTDR to an ophthalmologist from primary care.

An initiative to improve follow-up of patients with diabetic retinopathy

BACKGROUND

This study describes the implementation of an electronic medical record (EMR)-based initiative aimed at identifying and reducing the number of patients with diabetic retinopathy (DR) lost to follow-up (LTF).

METHOD

Providers were enlisted to review the EMRs and re-engage patients with DR seen 1 year prior and who had not returned for care within the past 6 months. Binary logistic regression analysis was used to identify demographic, clinical and sociomedical factors associated with being LTF, as well as those predictive of re-engagement.

RESULTS

Out of 673 patients with DR, 78 (12%) were identified as LTF. Patients LTF were more likely to be younger (p = 0.001) and have poorly controlled haemoglobin A1c (HbA1c ≥ 8%, p = 0.04) and cholesterol (LDL ≥ 100 mg/dL, p < 0.001) levels. These patients were also more likely to have completed fewer ophthalmology appointments (p < 0.001), and less likely to have had retinal imaging within the last year (p < 0.001). Charts reviewed 1 month after the EMR-based initiative revealed that 22 patients (28%) had been successfully re-engaged by providers, while 56 patients (72%) remained LTF. History of prior treatment for DR was associated with re-engagement by providers (p = 0.04). One month following the provider-based intervention, the LTF rate dropped to 8.3%, and by 1 year only 3.6% of the patients remained LTF.

CONCLUSIONS

Electronic medical record-based tools can successfully identify DR patients as being LTF, offering an opportunity for providers to re-engage patients in a timely manner. Future studies are needed to determine the long-term impact of patient re-engagement on DR outcomes and efficiency of clinical practice.

Development of a diabetic retinopathy screening model for a district health system in Limpopo Province, South Africa

Background: Diabetes mellitus (DM) and diabetic retinopathy (DR) are important issues in the district health system (DHS) of South Africa (SA). Guidelines for the management of DR in SA were developed more than a decade ago but not effectively implemented.Aim: The aim of this study was to develop a suitable model for DR that could be effectively implemented by a team of healthcare practitioners (HCPs) to co-manage DM and DR in the DHS of SA.Setting: The study was conducted through Voortrekker District Hospital, Limpopo Province, SA.Methods: A saturated strategy sample study was employed, and questionnaires were distributed to 24 endocrinologists in both private and public practices in Gauteng Province and to three ophthalmologists and 10 medical officers (MOs) in ophthalmology in health institutions in Waterberg and Capricorn districts of Limpopo Province. The questionnaires distributed included questions relating to the recommended roles of primary healthcare (PHC) nurses, MOs in general practice, MOs in ophthalmology, ophthalmic nurses, optometrists, and ophthalmologists to manage patients with DM in the public sector. The Delphi technique was employed requiring experts to comment qualitatively and quantitatively to elicit the required information.Results: At PHC level, PHC nurses are to document a comprehensive patient case history and assess vitals before referring to MOs in general practice. Medical officers in general practice are to assess DM control and screen for target organ disease. All patients with DM are to be referred to optometrists for retinal photography. Optometrists and ophthalmic nurses are to detect, grade and monitor pre-proliferative stages of DR, and refer to MOs in ophthalmology or ophthalmologists at district or tertiary hospitals for surgical intervention or treatment.Conclusion: Based on the expertise of the endocrinologists and ophthalmologists concerned, a DR screening model for a DHS was proposed, reflecting the role of HCPs in the management of DM and DR in the DHS of Limpopo Province, SA.

Impact of systemic parameters before commencing anti-vascular endothelial growth factor therapy for diabetic macular edema - Pan-Indian survey of retina specialists

Purpose:

Intravitreal anti-vascular endothelial growth factor (VEGF) injection therapy has emerged as the mainstay of treatment in the management of diabetic macular edema (DME) today. Various systemic risk factors have to be considered before initiating anti-VEGF therapy. The aim of our study was to form a consensus on various systemic factors to consider before starting anti-VEGF therapy for DME.

Methods:

A questionnaire was created and sent across to various retina specialists across India. A Google™ form with various questions pertaining to what systemic parameters would one consider before giving anti-VEGF therapy for DME was sent to each of them by email/WhatsApp™/direct telephonic interview.

Results:

Of the 650 retina specialists contacted, 322 responded to the questionnaire. There was no difference in responses between private and institutional practitioners. The majority would consider RBS (85%), HbA1c (61%), blood pressure (63%), and renal function (57%) as a routine before administering the anti-VEGF injection, while the majority would not consider hemoglobin (63%) or lipid profile (55%) of the patient as a routine practice prior to administering the injection.

Conclusion:

In our study, most VR specialists prefer to consider RBS, HbA1c, BP, and renal profile (creatinine) routinely prior to anti-VEGF injection. We suggest that it is important to consider blood pressure control, glycemic control, HbA1c, Hb, lipid profile, and renal profile (UACR, eGFR, and creatinine) prior to anti-VEGF therapy in all diabetic patients and to discuss the need for statins in patients with dyslipidemias with the physician.

Diabetic macular edema treatment guidelines in India: All India Ophthalmological Society Diabetic Retinopathy Task Force and Vitreoretinal Society of India consensus statement

Diabetic macular edema (DME) is a common cause of moderate visual impairment among people with diabetes. Due to the rising number of people with diabetes in India, the absolute numbers of people with DME are significant. There are several treatment options for DME, and the choice of treatment is based on the availability of retinal specialists and infrastructure for the delivery of treatment. A major challenge is the out-of-pocket expenditure incurred by patients as most treatment options are costly. Treatment also varies based on the associated ocular and systemic conditions. The All India Ophthalmology Society (AIOS) and the Vitreo-Retinal Society of India (VRSI) have developed this consensus statement of the AIOS DR task force and VRSI on practice points of DME management in India. The objective is to describe the preferred practice patterns for the management of DME considering the different presentations of DME in different clinical scenarios.

Modulation of SOD3 Levels Is Detrimental to Retinal Homeostasis

Retinal oxidative stress is a common secondary feature of many retinal diseases. Though it may not be the initial insult, it is a major contributor to the pathogenesis of highly prevalent retinal dystrophic diseases like macular degeneration, diabetic retinopathy, and retinitis pigmentosa. We explored the role of superoxide dismutase 3 (SOD3) in retinal homeostasis since SOD3 protects the extracellular matrix (ECM) from oxidative injury. We show that SOD3 is mainly extracellularly localized and is upregulated as a result of environmental and pathogenic stress. Ablation of SOD3 resulted in reduced functional electroretinographic responses and number of photoreceptors, which is exacerbated with age. By contrast, overexpression showed increased electroretinographic responses and increased number of photoreceptors at young ages, but appears deleterious as the animal ages, as determined from the associated functional decline. Our exploration shows that SOD3 is vital to retinal homeostasis but its levels are tightly regulated. This suggests that SOD3 augmentation to combat oxidative stress during retinal degenerative changes may only be effective in the short-term.

Increasing metabolic variability increases the risk for vitrectomy in proliferative diabetic retinopathy

PURPOSE

Proliferative diabetic retinopathy (PDR) can be treated by retinal photocoagulation, but in some cases, the treatment is initiated too late or is insufficient so that the disease advances to a stage requiring vitrectomy. There is a need to identify risk factors that can predict if patients with PDR will develop complications in need for vitrectomy.

METHODS

Survival analysis with death as competing risk was used to study systemic risk factors for PDR progression to a complication in need for vitrectomy in right eyes of all 1288 diabetic patients from the Aarhus area, Denmark, who had developed proliferative retinopathy in the right eye during the 25 years period from 1 July 1994 until 1 July 2019.

RESULTS

The overall cumulative incidence of reaching a vitrectomy end point in the right eye was 24.1% (n = 311). In 9.3% (n = 120) of the patients where vitrectomy had been performed together with the first photocoagulation, the age of onset of diabetes was significantly higher (p < 0.0001), the diabetes duration longer (p < 0.035) and BMI higher (p < 0.01) than in the patients who had been vitrectomized later than the first photocoagulation. The risk for vitrectomy was significantly increased by high variability of HbA1c before the development of PDR (p < 0.0001), but not by other parameters known to increase the risk for developing PDR.

CONCLUSION

Increasing variability of HbA1c before the development of PDR increases the risk for progression to a complication in need of vitrectomy. The need for vitrectomy is unaffected by other risk factors known to increase the risk for developing PDR.

Utilization of Remote Diabetic Retinal Screening in a Suburban Healthcare System

Purpose

We conducted a cross-sectional study to assess the utilization of a tele-ophthalmology screening program in a low-risk, suburban population of patients with diabetes.

Methods

A total of 214 diabetic patients without previously documented diabetic retinopathy (DR) underwent point-of-care non-mydriatic fundus photography through their primary care providers at five Beth Israel Lahey Health locations. The characteristics of the patients who received remote screening were compared with those patients who were eligible for screening but did not take part in the program. Time-driven activity-based costing (TDABC) was implemented to examine the cost of screening by tele-ophthalmology compared with in-person examinations.

Results

Tele-ophthalmology screening was more likely to be provided for patients who were younger (OR 0.985; 95% CI 0.973–0.997, p=0.016), who were obese (OR 2.04; 95% CI: 1.47–2.84, p=0.008), who had an HbA1c above 8.0% (OR 1.60; 95% CI: 1.13–2.26, p=0.031), or who had an eye examination in the past year (OR 5.55; 95% CI: 3.89–7.92, p<0.001). Those patients newly diagnosed with DR because of the program were more likely to have diabetic nephropathy (OR 7.79; 95% CI: 1.73–35.05, p=0.007). TDABC identified a health system cost-savings of between $8 and $29 per patient screened by tele-ophthalmology compared with the cost of in-person eye examinations.

Conclusion

Tele-ophthalmology presents an opportunity to reduce the costs of screening patients without prior evidence of DR, especially those who have completed a comprehensive eye examination within the prior year.

Management of Complications and Vision Loss from Proliferative Diabetic Retinopathy

PURPOSE OF REVIEW

Diabetes can be associated with profound visual loss due to several mechanisms. As the duration of diabetes and blood glucose levels increase, these changes become more severe. The proliferation of new blood vessels, vitreous hemorrhage, and tractional retinal detachments may ultimately result and can be devastating to visual function. New advances, including anti-vascular endothelial growth factor (VEGF) medications and innovative microsurgical instruments, have provided additional methods for the management of diabetic retinopathy in the clinic and in the operating room, leading to improved outcomes.

RECENT FINDINGS

Advances in earlier treatment of proliferative diabetic retinopathy, especially with anti-VEGF injections, allow for a reduction in severity, improved vision, and more controlled and successful surgery. Modern surgical techniques and instrumentation have also allowed for improved patient outcomes. Future research into sustained delivery and release of anti-VEGF, reducing the need for frequent in-office injections, may prove to be additionally beneficial. Over the last decade, anti-VEGF has become an increasingly common treatment modality for the management of proliferative diabetic retinopathy, vitreous hemorrhages, and tractional retinal detachments. Further research is needed to determine the ideal method of delivery and timing of the treatment.

SHORT-WAVELENGTH AUTOMATED PERIMETRY IN DIABETIC PATIENTS WITHOUT RETINOPATHY

AIM

To compare the results of short-wavelength automated perimetry (SWAP) in diabetic patients without retinopathy and healthy subjects and show if it is possible to detect an abnormal function of the retina in diabetic patients before vascular changes on the retina develop. Further, the effect of diabetes duration and long-term glycaemic control on the visual field was examined.

METHODS

The study group included 22 patients with diabetes type 1 or 2, without any signs of retinopathy. The control group consisted of 21 healthy subjects. Short-wavelength automated perimetry was performed on the Humphrey Field Analyzer (HFA 860, Carl Zeiss Meditec), SITA SWAP, 24-2 test. In diabetic patients, the duration of diabetes and the level of glycohemoglobin (HbA1c) was registered. The visual field indices MD (mean deviation) and PSD (pattern standard deviation) were compared between both groups by the Mann-Whitney test. The correlation between the visual field indices, HbA1c and duration of diabetes was assessed by the Spearman correlation coefficient.

RESULTS

The mean value of MD in the study and control group was -3.64±3.66 dB and -1.48±2.12 dB respectively, the values in the study group were significantly lower (p &lt; 0.05). Mean PSD in the study group was 2.92±1.04 dB and 2.23±0.33 dB in the control group, again the difference was statistically significant (p &lt; 0.05). Patients in the study group suffered from diabetes for 17±9.4 years in average. The mean value of HbA1c in the study group was 60.64±16.63 mmol/mol. A significant correlation was found only for PSD and HbA1c (p &gt; 0.05). The duration of diabetes had no effect on either of the visual field indices.

CONCLUSION

Short-wavelength sensitivity of retina seems to be affected in diabetic patients without clinically significant retinopathy suggesting a neuroretinal impairment at early stages of the retinopathy. We found no association between the visual field and the control or duration of diabetes.

Mode of Delivery in the Setting of Repeated Vitreous Hemorrhages in Proliferative Diabetic Retinopathy: A Case Report and Review of the Literature

The state of pregnancy affects all organ systems including the eyes. Progression of diabetic retinopathy (DR) is a known association. In proliferative DR, there is an increased risk of vitreous hemorrhage (VH) during spontaneous vaginal delivery (SVD) due to the Valsalva maneuver. A 30-year-old female with poorly controlled type I diabetes and hypothyroidism on treatment was following up with the antenatal services at our hospital. This was her second pregnancy having had a previous miscarriage. Three months into her pregnancy, our Ophthalmology service was consulted to assess her and give our advice regarding the safest mode of delivery for her. Questioning revealed that she was following regularly elsewhere for proliferate DR with previous interventions and history of multiple and repeated VHs. When she was seen in our Ophthalmology clinic, she was anxious about the mode of delivery that was best suited for her with regard to her ocular condition. On examination, her visual acuity (VA) without correction was 20/40 in both eyes, improving to 20/20 in the right eye and 20/30 in the left eye after refraction. Her intra-ocular pressure was normal. A dilated fundus examination (DFE) showed changes of high-risk proliferative DR in both eyes and a VH in the right eye. Subsequent follow-up did not reveal any new complaints or concerns. She required one session of pan-retinal photocoagulation (PRP) in her first-trimester visit. DFE showed improvement in VH when compared to her initial examination. After discussing her condition with her obstetrician, it was decided to offer the patient a cesarean section (C/S) delivery, as her risk of developing VH during SVD was greater than normal. At 38 weeks of gestation, she delivered a healthy boy following an uneventful elective C/S. There were no visual complaints throughout her admission for the procedure or thereafter. During the reproductive age, DR is a leading cause of decreased vision. Pregnancy is an independent risk factor for progression of DR, with the stage of DR prior to conception being another. If not managed well, proliferative DR can result in VH, with the risk also existing in relation to SVD due to recurrent Valsalva maneuvers during labor. Our patient who initially presented with proliferative DR in both eyes and a VH in the right eye received one session of PRP to both eyes in the first trimester and was closely followed up throughout her pregnancy thereafter. When her due date neared, it was decided that the safest and most suitable mode of delivery was an elective C/S due to her increased risk of VH related to Valsalva maneuvers during SVD, especially since this was to be her first delivery.

Diet and risk of visual impairment: a review of dietary factors and risk of common causes of visual impairment

Age-related macular degeneration, diabetic retinopathy, cataract, and glaucoma remain the leading causes of visual impairment in developed nations, resulting in a substantial treatment burden on sufferers and health care systems. Despite significant advances in diagnostic testing and therapeutics, population-based strategies to reduce the burden of these diseases remain limited. However, there is some evidence that these diseases may share overlapping risk factors, particularly in regard to dietary intake and antioxidant status, and it is thus possible that dietary modification may reduce both the prevalence and severity of these conditions. In particular, dietary intake of green leafy vegetables, hyperglycemia/glycemia index, and omega-3 fatty acid intake, as well as overall dietary patterns, may affect risk of one or more of these conditions. In this review, we analyse the evidence for dietary intake and the association with these conditions, and provide insights into possible modifications that may thus simultaneously reduce the risk of visual impairment from multiple causes, including improving dietary intake of green leafy vegetables and reducing dietary glycemic index, both of which have been associated with a decreased risk of multiple causes of visual impairment.

Importance of the Use of Oxidative Stress Biomarkers and Inflammatory Profile in Aqueous and Vitreous Humor in Diabetic Retinopathy

Diabetic retinopathy is one of the leading causes of visual impairment and morbidity worldwide, being the number one cause of blindness in people between 27 and 75 years old. It is estimated that ~191 million people will be diagnosed with this microvascular complication by 2030. Its pathogenesis is due to alterations in the retinal microvasculature as a result of a high concentration of glucose in the blood for a long time which generates numerous molecular changes like oxidative stress. Therefore, this narrative review aims to approach various biomarkers associated with the development of diabetic retinopathy. Focusing on the molecules showing promise as detection tools, among them we consider markers of oxidative stress (TAC, LPO, MDA, 4-HNE, SOD, GPx, and catalase), inflammation (IL-6, IL-1ß, IL-8, IL-10, IL-17A, TNF-α, and MMPs), apoptosis (NF-kB, cyt-c, and caspases), and recently those that have to do with epigenetic modifications, their measurement in different biological matrices obtained from the eye, including importance, obtaining process, handling, and storage of these matrices in order to have the ability to detect the disease in its early stages.

Vitreous hemorrhage in diabetes patients with proliferative diabetic retinopathy undergoing hemodialysis

AIMS/INTRODUCTION

For diabetes patients undergoing hemodialysis, vitreous hemorrhage seems to be a hemodialysis-induced hemorrhagic complication because of the effect of systemic anticoagulation. However, it is unclear whether hemodialysis is associated with vitreous hemorrhage in diabetes patients. We therefore carried out this cohort study to clarify the relationship between hemodialysis and vitreous hemorrhage in diabetes patients with proliferative diabetic retinopathy.

MATERIALS AND METHODS

This was a single-center, retrospective, cohort study. We compared the incidence of vitreous hemorrhage in non-vitrectomized proliferative diabetic retinopathy eyes between the hemodialysis group (145 eyes) and peritoneal dialysis group (36 eyes), which does not require the use of systemic anticoagulation (parallel-group study), and in hemodialysis patients in the 12-month period before and after the start of hemodialysis (before-after study). We also determined the risk factors for vitreous hemorrhage after the start of hemodialysis based on the patients' systemic and ophthalmic characteristics.

RESULTS

There was no significant difference in the first-year incidence of vitreous hemorrhage between the hemodialysis (23.4%) and peritoneal dialysis groups (22.2%, P = 1.000). The incidence of vitreous hemorrhage in the dialysis period (23.4%) was significantly lower than that in the predialysis period (35.2%, P = 0.008). Only application of panretinal photocoagulation within the 6 months immediately before hemodialysis was significantly associated with the incidence of vitreous hemorrhage after the start of hemodialysis (P < 0.001).

CONCLUSIONS

Hemodialysis therapy does not seem to be associated with a higher risk of vitreous hemorrhage in diabetes patients with proliferative diabetic retinopathy.

Current management of diabetic tractional retinal detachments

Twenty-five percent of diabetes-related vision loss stems from complications of proliferative diabetic retinopathy (PDR). Panretinal photocoagulation has been the preferred treatment of high-risk PDR for decades and more recently intravitreal injections of drugs that inhibit the actions of vascular endothelial growth factor have become popular. But despite these treatments PDR may progress uncontrollably to advanced pathologies such as traction retinal detachments (TRDs), combined traction/rhegmatogenous retinal detachments (TRD/RRDs), vitreous hemorrhages, rubeosis iridis, and traction maculopathies, which produce mild-to-severe loss of vision. TDR have long been the most common indication for PDR-related vitreoretinal surgery. Vitrectomy surgery is indicated for recent (<6 months duration) TRD involving the macula, progressive TRD that threatens the macula, and recent data suggest that chronic macula-involving TRDs (>6 months duration) may also benefit. Combined TRD/RRD represents a particularly challenging surgical condition but advances in surgical instrumentation, dissection techniques, and post-operative tamponade have produced excellent success rates. The recent development of small-gauge vitrectomy systems has persuaded most surgeons to switch platforms since these appear to produce shorter surgical times and quicker post-operative recoveries. Pre-operative injections of bevacizumab are frequently administered for persistent neovascularization to facilitate surgical dissection of pre-retinal fibrosis and reduce the incidence of post-operative hemorrhages. Recent trends toward earlier surgical intervention and expanded indications are likely to continue as surgical instrumentation and techniques are further developed.

Diagnostic and prognostic role of serum miR-20b, miR-17-3p, HOTAIR, and MALAT1 in diabetic retinopathy

Noncoding RNAs are emerging biomarkers for many diseases including diabetic retinopathy (DR). This study aimed to measure the expression levels of serum miR-20b, miR-17-3p, HOTAIR, and MALAT1 in DR patients. A total of 80 patients diagnosed as type 2 diabetes (T2D) and 81 healthy subjects were recruited in this study. T2D patients were divided into three groups: nondiabetic retinopathy (NDR) group (30 patients), nonproliferative diabetic retinopathy (NPDR) group (30 patients), and proliferative diabetic retinopathy (PDR) group (20 patients). Quantitative real-time polymerase chain reaction (PCR) was used to assess the expression of serum miR-20b, miR-17-3p, HOTAIR, and MALAT1. We found a significant decrease in serum miR-20b and a significant increase in serum HOTAIR and MALAT1 in NDR patients compared to healthy subjects. Also, we revealed a significant decrease in serum miR-20b and miR-17-3p and a significant increase in serum HOTAIR and MALAT1 in each of NPDR and PDR groups when compared with healthy subjects. Furthermore, we reported a significant decrease in miR-20b and miR-17-3p and a significant increase in HOTAIR and MALAT1in DR as well as in PDR patients when compared with NDR patients. However, on comparing NPDR with NDR patients, no significant difference was observed regarding the expression levels of miR-20b and miR-17-3p, in contrast, significant elevation of serum HOTAIR and MALAT1 was found in NPDR. Moreover, we observed a significant decrease in serum miR-20b and miR-17-3p and a significant increase in serum HOTAIR and MALAT1 in PDR group relative to NPDR group. Receiver operating characteristic (ROC) curve was used for evaluating the diagnostic value of the examined serum noncoding RNAs as novel biochemical indicators detecting severity of DR. Our analyses suggested that the examined serum noncoding RNAs may discriminate DR (PDR and NPDR) from NDR. Furthermore, these noncoding RNAs (less importantly miR-17) can be used as promising novel biomarkers for prediction DR severity, distinguishing PDR from NPDR patients. We can conclude that serum miR-20b, miR-17-3p, HOTAIR, and MALAT1 may be used as noninvasive biomarkers for screening of DR and early diagnosis of PDR. © 2018 IUBMB Life, 71(3):310-320, 2019.

Review of the literature examining the association between physical activity and retinopathy

The main aim of this review was to evaluate the association between physical activity and retinopathy. Secondary aims included evaluating the association between sedentary behavior and retinopathy, and evaluating the association between physical activity/sedentary behavior on health outcomes among patients with existing retinopathy. Twenty-one articles met our criteria for inclusion in this review. Among the 19 studies evaluating the main aim (physical activity and retinopathy), 53% (n = 10/19) demonstrated evidence of a favorable (inverse) association between physical activity and retinopathy, 42% (n = 8/19) reported a null association physical activity and retinopathy, and 5% (n = 1/19) presented evidence for a detrimental association between physical activity and retinopathy. Regarding the secondary aims, one study demonstrated a detrimental association between sedentary behavior and retinopathy. Similarly, one study demonstrated that physical activity was protective against early mortality among those with mild retinopathy. This review identifies an 'indeterminate' association between physical activity and retinopathy. Too few studies evaluated the association between sedentary behavior and retinopathy or the effects of physical activity on health outcomes among those with existing retinopathy.

Acute and Chronic Hyperglycemia Elicit JIP1/JNK-Mediated Endothelial Vasodilator Dysfunction of Retinal Arterioles

Purpose

Hyperglycemia, a hallmark of diabetes mellitus, is associated with retinal inflammation and impairment of endothelium-dependent nitric oxide (NO)–mediated dilation of retinal arterioles. However, molecular mechanisms involved in this diminished endothelial vasodilator function remain unclear. We examined whether inflammatory stress-activated kinases, c-Jun N-terminal kinase (JNK) and p38, contribute to retinal arteriolar dysfunction during exposure to acute and chronic hyperglycemia.

Methods

Retinal arterioles were isolated from streptozocin-induced diabetic pigs (2 weeks; chronic hyperglycemia, 471 ± 23 mg/dL) or age-matched control pigs (euglycemia, 79 ± 5 mg/dL), and then cannulated and pressurized for vasoreactivity study. For acute hyperglycemia study, vessels from nondiabetic pigs were exposed intraluminally to high glucose (25 mM ≈ 450 mg/dL) for 2 hours, and normal glucose (5 mM ≈ 90 mg/dL) served as the control.

Results

Endothelium-dependent vasodilation to bradykinin was reduced in a similar manner after exposure to acute or chronic hyperglycemia. Administration of NO synthase inhibitor N^G-nitro-L-arginine methyl ester (L-NAME) nearly abolished vasodilations either in control (euglycemia and normal glucose) or hyperglycemic (acute and chronic) vessels. Treatment of either acute or chronic hyperglycemic vessels with JNK inhibitor SP600125 or JNK-interacting protein-1 (JIP1) inhibitor BI-78D3, but not p38 inhibitor SB203580, preserved bradykinin-induced dilation in an L-NAME–sensitive manner. By contrast, endothelium-independent vasodilation to sodium nitroprusside was unaffected by acute or chronic hyperglycemia.

Conclusions

Activation of JIP1/JNK signaling in retinal arterioles during exposure to acute or chronic hyperglycemia leads to selective impairment of endothelium-dependent NO-mediated dilation. Therapeutic targeting of the vascular JNK pathway may improve retinal endothelial vasodilator function during early diabetes.

Clinical Characteristics of Patients with Newly Diagnosed Diabetic Macular Edema in Turkey: A Real-Life Registry Study-TURK-DEM

Purpose. To evaluate the clinical and diagnostic characteristics of patients with newly diagnosed diabetic macular edema (DME) in Turkey in a real-life setting. Methods. A total of 945 consecutive patients (mean (SD) age: 61.3 (9.9) years, 55.2% male) with newly diagnosed DME were included. Data on patient demographics, comorbidities, ocular history, ophthalmic examination findings including type of DME, central macular thickness (CMT) via time domain (TD) and spectral domain (SD) optical coherence tomography (OCT), and planned treatments were recorded. Results. OCT (98.8%) and fundoscopy (92.9%) were the two most common diagnostic methods. Diffuse and focal DMEs were detected in 39.2% and 36.9% of cases, respectively. Laser photocoagulation (32.1%) and antivascular endothelial growth factors (anti-VEGF; 31.8%) were the most commonly planned treatments. The median CMT in the right eye was significantly greater in untreated than in treated patients [376.5 μm (range: 160–840) versus 342 μm (range: 146–999) (p = 0.002)] and in the left eye [370 μm (range: 201–780) versus 329 μm (range: 148–999) (p < 0.001)]. Conclusions. This study is the first large-scale real-life registry of DME patients in Turkey. SD-OCT and fundoscopy were the most common diagnostic methods. Laser photocoagulation and anti-VEGF therapy were the most common treatments.

Hospital Prevalence of Retinopathy in Patients with Newly-Diagnosed Type 2 Diabetes

Aims:

To determine the period prevalence of diabetic retinopathy (DR) and the associated factors in patients with newly-diagnosed Type 2 diabetes mellitus (T2DM).

Subjects and Methods:

In this prospective study, all newly-diagnosed T2DM patients who attended the ophthalmology clinic at King Fahad Hospital of the University between January 2012 and January 2015, were examined for DR. After pupillary dilation, the ophthalmic fundus was examined by a retina consultant using slit-lamp indirect ophthalmoscopy. Risk factors such as gender, age, hypertension, nephropathy, the level of glycated hemoglobin (Hb), microalbuminuria, and hyperlipidemia were evaluated for possible association with DR at the time of diagnosis.

Results:

The study included 112 newly-diagnosed T2DM patients. DR was present in seven patients (6.25%) with a mean age of 53.4 ± 6.4 years, four of whom were females (57%). Nonproliferative DR was present in all patients with DR, two patients (28.6%) presented with bilateral clinically significant macular edema requiring laser photocoagulation treatment and intravitreal anti-vascular endothelial growth factor therapy. In the study cohort, elevated hemoglobin A1C levels (HbA1C) were detected in 55 patients (49.1%), microalbuminuria in 28 (25.0%), hypertension in 31 (27.6%), hyperlipidemia in 65 (58.0%) and obesity in 43 (38.1%). At the time of T2DM diagnosis, uncontrolled HbA1C levels were significantly associated with the presence of retinopathy (P = 0.045); however, no statistical significance was observed for the remaining risk factors.

Conclusion:

The frequency of retinopathy in newly-diagnosed T2DM patients was similar to previous reports. Vision-threatening maculopathy was present in two of seven patients, requiring further intervention. Therefore, early screening is strongly recommended for all newly-diagnosed T2DM patients. Prospective studies with a large sample size are needed to verify the risk factors for these patients.

Does tight control of systemic factors help in the management of diabetic retinopathy?

Diabetic retinopathy (DR), one of the leading causes of preventable blindness, is associated with many systemic factors that contribute to the development and progression of this microvascular complication of diabetes. While the duration of diabetes is the major risk factor for the development of DR, the main modifiable systemic risk factors for development and progression of DR are hyperglycemia, hypertension, and dyslipidemia. This review article looks at the evidence that control of these systemic factors has significant benefits in delaying the onset and progression of DR.

Molecular Markers of Diabetic Retinopathy: Potential Screening Tool of the Future?

Diabetic retinopathy (DR) is among the leading causes of new onset blindness in adults. Effective treatment may delay the onset and progression of this disease provided it is diagnosed early. At present retinopathy can only be diagnosed via formal examination of the eye by a trained specialist, which limits the population that can be effectively screened. An easily accessible, reliable screening biomarker of diabetic retinopathy would be of tremendous benefit in detecting the population in need of further assessment and treatment. This review highlights specific biomarkers that show promise as screening markers to detect early diabetic retinopathy or even to detect patients at increased risk of DR at the time of diagnosis of diabetes. The pathobiology of DR is complex and multifactorial giving rise to a wide array of potential biomarkers. This review provides an overview of these pathways and looks at older markers such as advanced glycation end products (AGEs), inflammatory markers, vascular endothelial growth factor (VEGF) as well as other newer proteins with a role in the pathogenesis of DR including neuroprotective factors such as brain derived neurotrophic factor (BDNF) and Pigment Epithelium Derived Factor (PEDF); SA100A12, pentraxin 3, brain natriuretic peptide, apelin 3, and chemerin as well as various metabolites such as lipoprotein A, folate, and homocysteine. We also consider the possible role of proteins identified through proteomics work whose levels are altered in the sera of patients with DR as screening markers though their role in pathophysiology remains to be characterized. The role of microRNA as a promising new screening marker is also discussed.

The management of diabetic retinopathy in the public sector of eThekwini district of KwaZulu-Natal

Background: Estimates from the year 1990–2010 showed an increase in blindness and vision impairment (moderate or severe) because of diabetic retinopathy (DR) in Sub-Saharan Africa’s sub-regions (central, eastern, southern and western Africa).1 The rate of DR in South Africa is expected to increase because of the lack of screening protocols and policies for the management of diabetic eye disease in the district health system of South Africa. Aim: The purpose of this study was to determine the current role of healthcare practitioners (HCPs) towards managing DR in the eThekwini district of KwaZulu-Natal.Method: A cross-sectional study was conducted, and questionnaires were distributed to a total of 104 HCPs in public health institutions situated in the northern eThekwini district of KwaZulu-Natal. Clinics and community health centres (CHCs) were selected based on the assumption that primary healthcare nurses, medical officers (MOs) and ophthalmic nurses and/or optometrists practice at these institutions. The hospitals selected were the referral institutions for the selected clinics and CHCs. The questionnaires distributed included questions relating to diabetic patient registers, referrals to and from other HCPs, management of ocular complications, ocular screening methods, fundus examinations and involvement in screening programmes.Results: Over a third of the ophthalmologists (35.3%) indicated that DR was present at the initial examination in more than 50% of patients, though overall ophthalmologists reported loss of vision in at least one eye in fewer than 5% of patients on presentation. Less than half of the public sector general practitioners or MOs (40.6%) conducted fundus examinations but 90.6% did not dilate pupils, although 71.9% had knowledge on the use of a direct ophthalmoscope. Only 40.6% of the MOs discussed the ocular complications of uncontrolled diabetes mellitus (DM) with patients and 62.5% encouraged regular eye examinations. Less than 50% of the MOs (43.8%) referred patients complaining of visual difficulties to optometrists and 9.4% referred to the ophthalmic nurses. Only 6.25% referred patients with DM needing further evaluation to ophthalmologists. Data from the optometrists were inconclusive because of the poor response rate of 5 (20%). None of the ophthalmic nurses reported doing fundus photography or refractions. Two-thirds of the ophthalmic nurses were interested in training to properly grade DR.Conclusion: The study established that there are key challenges in referral, training and practice in the management of DR. These need to be addressed in order to develop a comprehensive approach for the prevention and management of visual impairment and blindness because of DM.

Diabetic retinopathy

Diabetic retinopathy (DR) is a common complication of diabetes mellitus and is a major cause of vision loss in middle-aged and elderly people. One-third of people with diabetes have DR. Severe stages of DR include proliferative DR, caused by the abnormal growth of new retinal blood vessels, and diabetic macular oedema, in which there is exudation and oedema in the central part of the retina. DR is strongly associated with a prolonged duration of diabetes, hyperglycaemia and hypertension. It is traditionally regarded as a microvascular disease, but retinal neurodegeneration is also involved. Complex interrelated pathophysiological mechanisms triggered by hyperglycaemia underlie the development of DR. These mechanisms include genetic and epigenetic factors, increased production of free radicals, advanced glycosylation end products, inflammatory factors and vascular endothelial growth factor (VEGF). Optimal control of blood glucose and blood pressure in individuals with diabetes remains the cornerstone for preventing the development and arresting the progression of DR. Anti-VEGF therapy is currently indicated for diabetic macular oedema associated with vision loss, whereas laser photocoagulation prevents severe vision loss in eyes with proliferative DR. These measures, together with increasing public awareness and access to regular screening for DR with retinal photography, and the development of new treatments to address early disease stages, will lead to better outcomes and prevent blindness for patients with DR.

Awareness, Practices and Treatment Seeking Behavior of Type 2 Diabetes Mellitus Patients in Delhi

Background:

Type 2 diabetes mellitus is a multisystem disorder that is associated with number of complications. Patient's awareness and practices are crucial components in reducing the burden of diseases and its complications.

Aim:

To assess patient's knowledge about their disease and its complications, practices, treatment seeking behavior and average expenditure incurred by its management.

Subjects and Methods:

A community based cross-sectional study was conducted in rural and urban slum areas of Delhi selecting a total of 98 diabetic patients diagnosed during the two community surveys and interviewed using pretested and predesigned questionnaire. Data were analyzed using SPSS software, version 17 (Chicago II, USA). Chi-square, fisher or Mann–Whitney tests were used for test of significance and considered statistically significant at P < 0.05.

Results:

Of 98 participants, 31.6% (31/98) were from urban slum area, and 68.4% (67/98) were from the rural area. In both urban and rural areas, majority were Hindu, married, literate and unemployed. Significantly less subjects (61.3%, 19/31) of urban slum area than of rural area (85.1%, 57/67) could name at least one complication of DM (P < 0.01, odds ratio [OR] =3.6, 95% confidence interval [CI] =1.3–9.6). Majority of participants in both urban slum and rural area have knowledge about at least one component of management but significantly lesser in urban (83.9%, 26/31) than rural area (97.0%, 65/67) were reported (P = 0.02, OR = 6.2, 95% CI = 1.1–34.2). Significantly more subjects (29.0%, 9/31) in urban slum area than rural areas (7.5%, 5/67) reported that they were not taking any treatment for DM (P < 0.01, OR = 0.2, 95% CI = 0.1–0.6). In urban area, 32.2% (10/31) patients told that it is a burden on their family while in rural area 44.7% (30/67) of the patients told that they have to squeeze money from the family expenditure to afford drugs.

Conclusion:

Patients need to be made aware of the asymptomatic phase of DM and its long term complications. At the same time, efforts should be made to sensitize them about the importance of taking regular treatment and management.

Hyperglycemia and Diabetes Downregulate the Functional Expression of TRPV4 Channels in Retinal Microvascular Endothelium

Retinal endothelial cell dysfunction is believed to play a key role in the etiology and pathogenesis of diabetic retinopathy. Numerous studies have shown that TRPV4 channels are critically involved in maintaining normal endothelial cell function. In the current paper, we demonstrate that TRPV4 is functionally expressed in the endothelium of the retinal microcirculation and that both channel expression and activity is downregulated by hyperglycaemia. Quantitative PCR and immunostaining demonstrated molecular expression of TRPV4 in cultured bovine retinal microvascular endothelial cells (RMECs). Functional TRPV4 activity was assessed in cultured RMECs from endothelial Ca2+-responses recorded using fura-2 microfluorimetry and electrophysiological recordings of membrane currents. The TRPV4 agonist 4α-phorbol 12,13-didecanoate (4-αPDD) increased [Ca2+]i in RMECs and this response was largely abolished using siRNA targeted against TRPV4. These Ca2+-signals were completely inhibited by removal of extracellular Ca2+, confirming their dependence on influx of extracellular Ca2+. The 4-αPDD Ca2+-response recorded in the presence of cyclopiazonic acid (CPA), which depletes the intracellular stores preventing any signal amplification through store release, was used as a measure of Ca2+-influx across the cell membrane. This response was blocked by HC067047, a TRPV4 antagonist. Under voltage clamp conditions, the TRPV4 agonist GSK1016790A stimulated a membrane current, which was again inhibited by HC067047. Following incubation with 25 mM D-glucose TRPV4 expression was reduced in comparison with RMECs cultured under control conditions, as were 4αPDD-induced Ca2+-responses in the presence of CPA and ion currents evoked by GSK1016790A. Molecular expression of TRPV4 in the retinal vascular endothelium of 3 months' streptozotocin-induced diabetic rats was also reduced in comparison with that in age-matched controls. We conclude that hyperglycaemia and diabetes reduce the molecular and functional expression of TRPV4 channels in retinal microvascular endothelial cells. These changes may contribute to diabetes induced endothelial dysfunction and retinopathy.

Early risk stratification in pediatric type 1 diabetes

In the late 1980s all Danish children with type 1 diabetes were invited for a nationwide evaluation of glycemic control. Approximately 75% (n = 720) participated and have later been referred to as The Danish Cohort of Pediatric Diabetes 1987 (DCPD1987). The results were surprisingly poor glycemic control among these young patients which lead to a great emphasis on glycemic control in the Danish Pediatric Departments. In 1995 the participants were invited for yet another evaluation but this time with main focus on early signs of microvascular complications - 339 participated. The mean HbA1c had remained at high levels (9.6%) and 60% of the participants had some level of Diabetic Retinopathy (DR). However, as the patients with DR mostly had the very milder forms it was believed that stricter glycemic control would reverse or at least stop progression of the disease in accordance with results from the large intervention study DCCT. This was investigated further at follow-up in 2011. The first study in the present thesis aimed to describe the 16-year incidence, progression and regression of DR in 185 participants from the DCPD1987 cohort. The 16-year incidence of proliferative retinopathy (PDR), 2-step progression and regression of DR was 31.0, 64.4, and 0.0%, respectively. As expected, the participants with PDR at follow-up had significantly higher HbA1c-values at both baseline and follow-up than those without PDR. However; a significantly larger decrease in HbA1c was also observed in the group with PDR over the study period, which in accordance with DCCT should have prevented the development of PDR to some extent. A surprisingly high incidence of proliferative retinopathy amongst young patients with type 1 diabetes in Denmark was found despite improvements in HbA1c over time. The improvement in HbA1c was either too small or happened too late. This study highlights that sight-threatening diabetic retinopathy remain a major concern in type 1 diabetes and the importance of early glycemic control. Identifying high-risk patients at a very early stage is not only desired for prevention of diabetic retinopathy - neuropathy and nephropathy similarly remain frequent in type 1 diabetes. Early risk stratification will allow for timely implementation of effective interventions and for individualized screening and diabetes care. The second and third studies of this thesis provide the longest prospective studies to date on both retinal vessel calibers and retinal fractal dimensions and their predictive value on diabetic microvascular complications. Semi-automated computer software has been developed to measure smaller changes in the retinal vessels on retinal photographs. Two of the first parameters to be reliably estimated by these programs were retinal vessel calibers and retinal vascular fractal dimensions (a quantitative measure on vascular complexity). There is very limited knowledge on their predictive value on diabetic complications thus far. In the second and third study, a consistent relation between narrower retinal arteriolar calibers, wider retinal venular calibers, lower fractal dimensions and the 16-year incidences of diabetic neuropathy, nephropathy and proliferative retinopathy was found. This has never been shown before. The results on vessel analyzes provides indications of a common pathogenic pathway for diabetic microvascular complications and therefore a possibility of universal risk estimation for development of neuropathy, nephropathy and retinopathy in type 1 diabetes.

Updates in the management of diabetic macular edema

Diabetes mellitus is a chronic disease which has multiple effects on different end-organs, including the retina. In this paper, we discuss updates on diabetic macular edema (DME) and the management options. The underlying pathology of DME is the leakage of exudates from retinal microaneurysms, which trigger subsequent inflammatory reactions. Both clinical and imaging techniques are useful in diagnosing, classifying, and gauging the severity of DME. We performed a comprehensive literature search using the keywords "diabetes," "macula edema," "epidemiology," "pathogenesis," "optical coherence tomography," "intravitreal injections," "systemic treatment," "hypertension," "hyperlipidemia," "anemia," and "renal disease" and collated a total of 47 relevant articles published in English language. The main modalities of treatment currently in use comprise laser photocoagulation, intravitreal pharmacological and selected systemic pharmacological options. In addition, we mention some novel therapies that show promise in treating DME. We also review systemic factors associated with exacerbation or improvement in DME.

Development and progression of diabetic retinopathy and associated risk factors in Korean patients with type 2 diabetes: the experience of a tertiary center

The aim of this study was to evaluate the incidence of and risk factors for the development of diabetic retinopathy (DR) and progression to proliferative DR (PDR) in Korean patients. Patients diagnosed with type 2 diabetes and followed for more than 5 years at a university-based clinic since 2000 were consecutively enrolled in this retrospective cohort study. Based on the DR classification at the initial and final visits, the incidence and progression of DR was determined and patient characteristics were compared according to DR progression. Hazard ratios of each putative risk factor for DR progression were calculated with a multivariate Cox proportional hazard model. Rate of DR development and progression to PDR were 32.1/1,000 and 26.2/1,000 person-years, respectively. A longer duration of diabetes and higher mean HbA1c level were significant risk factors for the development of DR. Regarding progression to PDR, higher mean HbA1c level, higher standard deviation of HbA1c, and higher urine albumin-to-creatinine ratio were significant risk factors. The rates of development of DR and progression to PDR in Koreans with type 2 diabetes are lower than those reported over the last decade. An inadequate blood glycemic control is the common risk factor for development and progression of DR.

Retinal vessel calibers predict long-term microvascular complications in type 1 diabetes: the Danish Cohort of Pediatric Diabetes 1987 (DCPD1987)

Diabetic neuropathy, nephropathy, and retinopathy cause significant morbidity in patients with type 1 diabetes, even though improvements in treatment modalities delay the appearance and reduce the severity of these complications. To prevent or further delay the onset, it is necessary to better understand common underlying pathogenesis and to discover preclinical biomarkers of these complications. Retinal vessel calibers have been associated with the presence of microvascular complications, but their long-term predictive value has only been sparsely investigated. We examined retinal vessel calibers as 16-year predictors of diabetic nephropathy, neuropathy, and proliferative retinopathy in a young population-based Danish cohort with type 1 diabetes. We used semiautomated computer software to analyze vessel diameters on baseline retinal photos. Calibers of all vessels coursing through a zone 0.5-1 disc diameter from the disc margin were measured and summarized as the central artery and vein equivalents. In multiple regression analyses, we found wider venular diameters and smaller arteriolar diameters were both predictive of the 16-year development of nephropathy, neuropathy, and proliferative retinopathy. Early retinal vessel caliber changes are seemingly early markers of microvascular processes, precede the development of microvascular complications, and are a potential noninvasive predictive test on future risk of diabetic retinopathy, neuropathy, and nephropathy.

Genetics of diabetic retinopathy

Diabetic retinopathy (DR) is a polygenic disorder. Twin studies and familial aggregation studies have documented clear familial clustering. Heritability has been estimated to be as high as 27 % for any DR and 52 % for proliferative diabetic retinopathy (PDR), an advanced form of the disease. Linkage analyses, candidate gene association studies and genome-wide association studies (GWAS) performed to date have not identified any widely reproducible risk loci for DR. Combined analysis of the data from multiple GWAS is emerging as an important next step to explain the unaccounted heritability. Key factors to future discovery of the genetic underpinnings of DR are precise DR ascertainment, a focus on the more heritable disease forms such as PDR, stringent selection of control participants with regards to duration of diabetes, and methods that allow combination of existing datasets from different ethnicities to achieve sufficient sample sizes to detect variants with modest effect sizes.

Current trends in the monitoring and treatment of diabetic retinopathy in young adults

The diagnosis and treatment of diabetic retinopathy (DR) in young adults have significantly improved in recent years. Research methods have widened significantly, for example, by introducing spectral optical tomography of the eye. Invasive diagnostics, for example, fluorescein angiography, are done less frequently. The early introduction of an insulin pump to improve the administration of insulin is likely to delay the development of diabetic retinopathy, which is particularly important for young patients with type 1 diabetes mellitus (T1DM). The first years of diabetes occurring during childhood and youth are the most appropriate to introduce proper therapeutic intervention before any irreversible changes in the eyes appear. The treatment of DR includes increased metabolic control, laserotherapy, pharmacological treatment (antiangiogenic and anti-inflammatory treatment, enzymatic vitreolysis, and intravitreal injections), and surgery. This paper summarizes the up-to-date developments in the diagnostics and treatment of DR. In the literature search, authors used online databases, PubMed, and clinitrials.gov and browsed through individual ophthalmology journals, books, and leading pharmaceutical company websites.

Evidence-based risk assessment and recommendations for physical activity clearance: Consensus Document 2011

The Physical Activity Readiness Questionnaire (PAR-Q) and the Physical Activity Readiness Medical Evaluation (PARmed-X) are internationally known preparticipation screening tools developed on the basis of expert opinion. The primary purposes of this consensus document were to seek evidence-based support for the PAR-Q and PARmed-X forms, to identify whether further revisions of these instruments are warranted, to determine how people responding positively to questions on the PAR-Q can be safely cleared without medical referral, and to develop exercise clearance procedures appropriate for various clinical conditions across the human lifespan. Seven systematic reviews were conducted, examining physical-activity-related risks and effective risk-stratification procedures for various prevalent chronic conditions. An additional systematic review assessed the risks associated with exercise testing and training of the general population. Two gap areas were identified and evaluated systematically: the role of the qualified exercise professional and the requisite core competencies required by those working with various chronic conditions; and the risks associated with physical activity during pregnancy. The risks associated with being physically inactive are markedly higher than transient risks during and following an acute bout of exercise in both asymptomatic and symptomatic populations across the lifespan. Further refinements of the PAR-Q and the PARmed-X (including online versions of the forms) are required to address the unique limitations imposed by various chronic health conditions, and to allow the inclusion of individuals across their entire lifespan. A probing decision-tree process is proposed to assist in risk stratification and to reduce barriers to physical activity. Qualified exercise professionals will play an essential role in this revised physical activity clearance process.

Diabetic retinopathy risk prediction for fundus examination using sparse learning: a cross-sectional study

BACKGROUND

Blindness due to diabetic retinopathy (DR) is the major disability in diabetic patients. Although early management has shown to prevent vision loss, diabetic patients have a low rate of routine ophthalmologic examination. Hence, we developed and validated sparse learning models with the aim of identifying the risk of DR in diabetic patients.

METHODS

Health records from the Korea National Health and Nutrition Examination Surveys (KNHANES) V-1 were used. The prediction models for DR were constructed using data from 327 diabetic patients, and were validated internally on 163 patients in the KNHANES V-1. External validation was performed using 562 diabetic patients in the KNHANES V-2. The learning models, including ridge, elastic net, and LASSO, were compared to the traditional indicators of DR.

RESULTS

Considering the Bayesian information criterion, LASSO predicted DR most efficiently. In the internal and external validation, LASSO was significantly superior to the traditional indicators by calculating the area under the curve (AUC) of the receiver operating characteristic. LASSO showed an AUC of 0.81 and an accuracy of 73.6% in the internal validation, and an AUC of 0.82 and an accuracy of 75.2% in the external validation.

CONCLUSION

The sparse learning model using LASSO was effective in analyzing the epidemiological underlying patterns of DR. This is the first study to develop a machine learning model to predict DR risk using health records. LASSO can be an excellent choice when both discriminative power and variable selection are important in the analysis of high-dimensional electronic health records.

Racial disparities in screening for diabetic retinopathy in youth with type 1 diabetes

Of 1112 children with type 1 diabetes, dilated eye exams were performed in 717 (64%). Children were less likely to be screened for diabetic retinopathy (DR) if they were black (OR=1.6; p=0.005) or had poorer diabetes control (p=0.002). Those at greatest risk for DR were least likely to be screened.