Active clinical trials for "Diabetic Retinopathy"

The objective of this research is to improve the care of ocular disease and disorders, in particular the changes in the eye associated with diabetes, by providing clinicians with dramatically improved ultrasonic images of the entire eye. The research combines advanced high-frequency, high-resolution ultrasonic annular arrays transducers with new processing techniques designed to overcome several limits that have been reached with conventional high frequency ultrasound systems. The investigators propose that diagnosis of eye diseases using annular arrays can be more effective than the conventional ultrasound images by at least 50%; i.e., that for every 2 posterior vitreous detachments detected conventionally, 3 will be detected with the annular arrays.

Vitrectomy is one of the major treatment methods for complications of diabetic retinopathy. As surgical techniques and instruments improve, high anatomical success may be achieved; however, functional results are less favorable. Despite attached retina, postoperative visual function may be affected by various macular and disc abnormalities. Major changes include optic atrophy, atrophic retina, poor macular perfusion, and structural alternations of the macula. Funduscopy, fluorescein angiography, and, more recently, optical coherence tomography (OCT) can be used to detect and document these alterations. Although fluorescein angiography is valuable in the assessment of various macular lesions as well as retinal vascular abnormalities, its usefulness in evaluating macular changes is limited in eyes that have undergone diabetic vitrectomy. The quality of the images may be compromised by mild diffuse hyperfluorescence in the posterior pole in middle and late phase angiography, which obscures capillary detail and subtle macular changes. Furthermore, quantification of changes may not be possible. Recently, optical coherence tomography has become very useful for the detection of vitreomacular abnormalities. The examination is noninvasive, can qualify the changes and detect subtle abnormalities not evident with other imaging studies. In this study, OCT was applied to investigate how common macular structure abnormalities are present after surgery for complications of diabetic retinopathy, and how they may affect visual prognosis.

The purpose of this study is to identify eyes that show worsening and disease progression (progressor phenotypes).

A variety of studies demonstrate that ocular blood flow is altered in diabetes and retinal perfusion abnormalities have been proposed to contribute to the pathogenesis of diabetic retinopathy. Various animal and human studies have demonstrated that retinal and optic nerve blood flow increase in response to diffuse luminance flicker. Based on studies with ERG, this effect has been attributed to augmented activity in the retinal ganglion cells and associated axons indicating a coupling mechanism between neuronal activity and retinal blood flow. Whereas a variety of studies describe the effects of flickering light on retinal and optic nerve head blood flow, the knowledge about this coupling in the diabetic retina is sparse. In view of the fact that neural activity and blood flow are strongly coupled in the human retina, one could hypothesize that neurodegenerative changes in the retina could contribute to the vascular dysregulation and in turn lead to changes of ocular perfusion. The investigators set out to investigate whether the coupling of neural activity and blood flow is impaired in patients with early stage diabetic retinopathy compared to those in healthy volunteers.

The study objective is to determine the course of changes in OCT measured macular thickness and visual acuity following a single session of focal photocoagulation for center-involved DME. The response will be evaluated separately in eyes with and without prior focal photocoagulation for DME. The purpose is to determine the proportion of eyes that continue to improve at least 5 letters in visual acuity or at least 10% in central retinal thickness after a session of focal photocoagulation. In addition, the study will explore whether any baseline factors can be identified that are predictive of the response. All subjects will have follow-up visits 8 weeks and 16 weeks post treatment. At the 16-week visit, study eyes are evaluated for change in retinal thickness and visual acuity from baseline. Treatment is to be deferred and follow up continued if visual acuity letter score has improved by >5 or OCT central subfield thickness has decreased by >10% compared with baseline. If visual acuity letter score has not improved by at least 5 and OCT central subfield thickness has not decreased by at least 10%, then the eye is classified as 'not improved' and the investigator may provide additional treatment. Follow up ends for eyes that receive additional treatment at this visit. However, if the investigator and participant elect to defer additional treatment (even if deferral criteria are not met), then follow up will continue until the study eye receives additional treatment for DME. Eyes continuing in follow up have visits every 8 weeks (+1week) as long as there has been continued improvement in visual acuity (letter score improved >5 ) or retinal thickness (central subfield thickness decreased by >10%) compared with the visit 16 weeks earlier. The longest follow-up time will be 48 weeks. By providing information on the length of time during which clinically meaningful improvement occurs following focal photocoagulation, clinicians will be better able to determine when further photocoagulation or other treatments should be considered for persistent DME. Depending on the results of this study, a future randomized clinical trial will be considered comparing the more aggressive retreatment photocoagulation regimen currently serving as the standard DRCR Network approach to focal photocoagulation for macular edema with the less aggressive regimen evaluated in this protocol.

The prevalence of diabetes mellitus (DM) is increasing worldwide. Diabetic retinopathy is the most prevalent complication of DM and a leading cause of visual impairment. Some factors are known to temporarily aggravate or improve diabetic retinopathy, but underlying pathophysiologic factors are still unknown. High-resolution imaging techniques of the retina and its supplying vascular networks now allow novel insight to subtle changes that cannot be appreciated in standard fundus examination. In detail, the investigators image study patients with optical coherence tomography (OCT) - technology, that provides morphological information of retinal structure and the supplying vessels in a non-invasive way. Retinal layer thickness as well as capillary density will be quantified and followed in patients that are in a critical period of disease transition to better understand the process of diabetic retinopathy.

The prevalence of diabetes is increasing and the management of the disease is nowadays considered a major challenge. Affected patients have increased mortality and morbidity as well as a significant drop in the quality of life. The complications of diabetes can be classified as microvascular (e.g. nephropathy, neuropathy or retinopathy) or macrovascular (e.g. cardiovascular or cerebrovascular). Several large-scale epidemiologic studies indicating that wider retinal venous caliber is strongly associated with the fasting glucose level as well as with diabetes. Another retinal vascular abnormality that is associated with diabetes is an abnormal retinal vascular response to flicker stimulation. Retinal vessel dilatation in response to stimulation with diffuse flicker light occurs due to a phenomenon called neurovascular coupling. This means that increased activity of neurons is associated with an increased retinal metabolism. This leads to a release of endogenous vasodilator substances and increased blood flow. However, previous studies were limited by the fact that retinal vessel diameters and blood flow were not measured simultaneously. The present study aims to investigate whether the response of retinal vessel diameters and blood flow velocities to flicker stimulation is altered in patients with diabetes. Both parameters will be measured in real time using Fourier Domain Doppler OCT.

The purpose of this study is to determine whether systemic administration of darbepoetin alpha results in the progression or regression of diabetic macular edema.

There is much evidence that localized low grade inflammatory processes may contribute to the microvascular complications of type 1 and type 2 diabetes mellitus including sight-threatening diabetic retinopathy. Some biomarkers for inflammation have been found to be elevated in diabetes patients and correlations between those biomarkers and the severity of diabetic complications have been found in the last years. The relation between this low grade inflammation and the microvascular changes observed in diabetic retinopathy is, however, not well characterized. In the present study patients with different stages of non-proliferative diabetic retinopathy will be included. Several markers of inflammation will be measured from blood samples. These markers will be related to vascular factors including flicker-induced vasodilatation as a marker of endothelial dysfunction and perifoveal leukocyte velocity and density as measured with the blue field entoptic phenomenon. In addition, the ophthalmologic status of the patients will be assessed according to the Modified Airlie House classification. A multiple regression model will be employed to study the association between the different methods.

The need for low vision services (LVS) will increase exponentially over the coming years due to the anticipated and exponential growth in the ageing population in Singapore and a rise in chronic non-communicable eye diseases. Finding the best evidenced-based management for chronic eye diseases contributing to low vision (LV) is therefore crucial. Improving patient responsibility is the key to managing LV effectively.1 This means achieving optimum self management (SM).2 However, there are currently no LV SM programs in Singapore and none has been evaluated using a randomized controlled trial (RCT) design, the gold standard methods to evaluate health interventions. The aims of this study are to assess the effectiveness of the 'Living Successfully with Low Vision (LSLV)' program in improving quality of life (QoL) in 160 elderly people with LV attending the Singapore National Eye Centre (SNEC) LV clinic. Of these, 80 will be randomly allocated to receive the LSLV 4-week SM program while the remaining 80 will receive the usual care. Comparisons will be made to determine the efficacy of the LSLV program. QoL, self-efficacy, emotional well being, and vision-specific distress will be assessed 2 weeks after training, and at six months and 12 months post intervention. This study will be the first evidenced-based RCT investigating the effectiveness of a novel vision-specific self-management strategy to improve QoL. It will also adopt a longitudinal design where the effectiveness of these interventions will be evaluated at 12 months-the first follow-up assessment of that duration at both national and international levels. Furthermore this will be the first study to characterize and profile the patients where the effect of the program did not demonstrate an improvement in both primary and secondary outcomes six months after its completion. The future clinical implications of this study include the potential to implement a successful model of LV rehabilitation in other tertiary centres around the country.