Excessive permeability in diabetic maculopathy

Novel imaging biomarkers in diabetic retinopathy and diabetic macular edema

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

Diabetic macular edema: classification, medical and laser therapy

PURPOSE

to propose and describe a new classification of diabetic macular edema (DME) based on its etiopathogenetic features and to present efficacy and safety data on medical and laser treatments currently used and under investigation.

METHODS

available literature on DME has been reviewed and information provided by contact lens biomicroscopy, fluorescein angiography and optical coherence tomomography has been combined; published data from trials and reports investigating effectiveness of medical and laser treatments were also analyzed.

RESULTS

DME was classified according to its main etiopathogenetic components: prevalently retinovascular, tractional and with taut attached posterior hyaloid, each of them having peculiar aspects on fundus, angiographic and tomographic examination. Focal laser treatment remains the only effective intervention, as shown by a large randomized controlled trial, but new less-invasive photocoagulation strategies (i.e., light laser photocoagulation and subthreshold micropulse diode laser) as well as pharmacological approaches (i.e., antioxidants, PKC inhibitors, aldose-reductase and AGE inhibitors, VEGF inhibitors, intravitreal triamcinolone) are emerging.

CONCLUSIONS

based on our review a classification of DME was developed that may prove useful in making the appropriate treatment decision; the new laser and pharmacological treatments currently investigated are promising and need to be confirmed by large, controlled clinical trials.

Diabetic macular edema: pathogenesis and treatment

Diabetic macular edema is a major cause of visual impairment. The pathogenesis of macular edema appears to be multifactorial. Laser photocoagulation is the standard of care for macular edema. However, there are cases that are not responsive to laser therapy. Several therapeutic options have been proposed for the treatment of this condition. In this review we discuss several factors and mechanisms implicated in the etiology of macular edema (vasoactive factors, biochemical pathways, anatomical abnormalities). It seems that combined pharmacologic and surgical therapy may be the best approach for the management of macular edema in diabetic patients.

Spontaneous regression of neovascularization at the disc in diabetic retinopathy

Neovascularization at the disc (NVD) is the most serious complication in diabetic retinopathy, and leads to vitreous hemorrhage and tractional retinal detachment. We report two cases of spontaneous regression of NVD in proliferative diabetic retinopathy. Two men (31 and 46 years old) with diabetes had NVD in both eyes. They were treated with panretinal photocoagulation on the left eye first, but their right eyes went untreated, because they did not revisit our clinic for several months. Fortunately, on revisit, their neovascularization had disappeared a few months later in both eyes, including their untreated right eyes. We could not find any specific causes for the spontaneous regression of the new vessels.

The National Diabetic Retinopathy Laser Treatment Audit. I. Maculopathy

The National Diabetic Retinopathy Laser Treatment Audit is a prospective survey of laser treatment for diabetic retinopathy throughout the United Kingdom. This paper describes the methodology of the study and presents data on 546 patients who were undergoing their first photocoagulation treatment for diabetic maculopathy (without proliferative retinopathy) during a 2 month period in 1995. Validation of the level of participation, patient demographic features, sources of referral, the level of systematic screening and waiting times are described. Maculopathy was detected as a result of systematic screening in 65.2%, whilst 12.3% of cases presented symptomatically. The percentage of cases treated within 8 weeks of listing was 83.1%, whilst 7% waited for more than 12 weeks for their laser treatment. The retinopathy features and the type of treatment given are also described. The maculopathy was said to be predominantly exudative in nature in 69.8% of cases, and 96.2% of these eyes were treated with focal macular laser. The maculopathy was said to be diffusely oedematous in nature in 8.6% of cases, and 78.7% of these eyes were treated with grid macular laser.

Surgical management of macular edema

Macular edema, often a component of diabetic retinopathy, can be complicated by many other diseases. It is considered to be multifactorial and difficult to treat. The relation of the vitreous and macular edema is discussed. We examined many eyes of patients with diabetic macular edema that improved after spontaneous posterior vitreous detachment or vitrectomy for proliferative diabetic retinopathy. Recent advances in vitreous surgery have enabled us to treat surgically eyes with good visual acuity. We began surgical treatment for macular edema without the fibrous membrane in 1990. Here we discuss our experience in surgical treatment of macular edema as contrasted to photocoagulation therapy. This review is based on the published and unpublished results of our cases of more than 100 eyes that underwent vitrectomy for diabetic macular edema.

Spontaneous regression of neovascularization at the disk and elsewhere in diabetic retinopathy

PURPOSE

To report three cases of spontaneous regression of new vessels of the disk and elsewhere in proliferative diabetic retinopathy.

METHODS

We retrospectively examined the clinical records of three young women (27, 26, and 19 years old) with insulin-dependent diabetes mellitus (for 16, eight, and 17 years, respectively) associated with other systemic diseases and referred to us for treatment of retinopathy. Complete general and ophthalmologic findings, visual field, and angiographic and electroretinographic examinations were available for each patient.

RESULTS

All the patients showed marked, spontaneous improvement of their proliferative retinopathy, with regression of new vessels. Assessment of metabolic control did not bring to light any noteworthy change during the period when the new vessels disappeared. Regression of new vessels was associated with a marked improvement in blood-retinal barrier breakdown as detected on fluorescein angiograms.

CONCLUSIONS

Although very unusual, spontaneous regression of neovascularizations in proliferative diabetic retinopathy can happen. We can offer no explanation for the regression of the new vessels and retinovascular hyperpermeability.

Diabetic macular edema. A review

Diabetic macular edema can be classified into a focal variety, characterized by focal leakage from microaneurysms, often with accumulation of extravascular lipoprotein in a circinate pattern around the focal leakage, and a diffuse variety, with diffuse leakage from retinal vessels often accompanied by cystoid macular changes. Laser photocoagulation is directed at microaneurysms for focal leakage and is applied in a grid pattern for diffuse leakage. Several prospective randomized clinical trials have shown that laser-treated eyes fare better than untreated eyes: there is a higher rate of modest visual improvement and a lower rate of visual deterioration in eyes treated with laser photocoagulation. In patients with diabetic macular edema, especially the diffuse variety, systemic factors also may play a pathogenic role. Fluid retention and hypertension due to cardiovascular and renal disease exacerbate retinal capillary leakage. Correction of systemic abnormalities (reduced blood pressure, diuresis) may reduce macular edema and should be included as part of the total management of patients with diabetic macular edema.

Prevention of blindness in diabetic retinopathy

Diabetic retinopathy, hitherto the most common cause of blindness in those between 30-64 years of age has become treatable. Both diabetic maculopathy and proliferative retinopathy can be treated effectively by photocoagulation. The treatment is most successful if given early, before visual loss becomes irreversible. Recently, vitrectomy with additional microsurgical techniques has been developed and shown to be effective in restoring vision to many patients blind from the complications of proliferative retinopathy.