Quantification of Diabetic Macular Edema

Rjh, Smith; Cm, Lee; Hc, Charles; Farber, Marilyn D.; Cunha-Vaz, Josè

doi:10.1001/archopht.1987.01060020072032

Cited by 46 publications

(22 citation statements)

References 13 publications

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“…Increasing osmotic pressure gradient Leaking capillaries and venules in the retina are closely associated with retinal and macular edema (104)(105)(106)(107)(108)(109). Fluorescein leakage has been used for diagnostic purposes in macular edema.…”

Section: How Do We Treat Edema?supporting

confidence: 38%

“…Retinal edema, such as in diabetic retinopathy and branch retinal vein occlusion, is highly associated with retinal capillary leakage (47,83,84,103). Fluorescein angiography and fluorophotometry have shown a close association between retinal and macular edema formation and fluorescein leakage, and this has indeed been one of the most frequently used clinical tools to evaluate retinal edema (104)(105)(106)(107)(108)(109). It is the leakage of plasma proteins that matters, due to the effect they have on osmotic pressure.…”

Section: Decreased Osmotic Pressure Gradientsupporting

confidence: 38%

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Physiology of vitreous surgery

Stefánsson

2008

Graefes Arch Clin Exp Ophthalmol

256

198

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Vitreous surgery has various physiological and clinical consequences, both beneficial and harmful. Vitrectomy reduces the risk of retinal neovascularization, while increasing the risk of iris neovascularization, reduces macular edema and stimulates cataract formation. These clinical consequences may be understood with the help of classical laws of physics and physiology. The laws of Fick, Stokes-Einstein and Hagen-Poiseuille state that molecular transport by diffusion or convection is inversely related to the viscosity of the medium. When the vitreous gel is replaced with less viscous saline, the transport of all molecules, including oxygen and cytokines, is facilitated. Oxygen transport to ischemic retinal areas is improved, as is clearance of VEGF and other cytokines from these areas, thus reducing edema and neovascularization. At the same time, oxygen is transported faster down a concentration gradient from the anterior to the posterior segment, while VEGF moves in the opposite direction, making the anterior segment less oxygenated and with more VEGF, stimulating iris neovascularization. Silicone oil is the exception that proves the rule: it is more viscous than vitreous humour, re-establishes the transport barrier to oxygen and VEGF, and reduces the risk for iris neovascularization in the vitrectomized-lentectomized eye. Modern vitreous surgery involves a variety of treatment options in addition to vitrectomy itself, such as photocoagulation, anti-VEGF drugs, intravitreal steroids and release of vitreoretinal traction. A full understanding of these treatment modalities allows sensible combination of treatment options. Retinal photocoagulation has repeatedly been shown to improve retinal oxygenation, as does vitrectomy. Oxygen naturally reduces VEGF production and improves retinal hemodynamics. The VEGF-lowering effect of photocoagulation and vitrectomy can be augmented with anti-VEGF drugs and the permeability effect of VEGF reduced with corticosteroids. Starling's law explains vasogenic edema, which is controlled by osmotic and hydrostatic gradients between vessel and tissue. It explains the effect of VEGF-induced vascular permeability changes on plasma protein leakage and the osmotic gradient between vessel and tissue. At the same time, it takes into account hemodynamic changes that affect the hydrostatic gradient. This includes the influence of arterial blood pressure, and the effect oxygen (laser treatment) has in constricting retinal arterioles, increasing their resistance, and thus reducing the hydrostatic pressure in the microcirculation. Reduced capillary hydrostatic pressure and increased osmotic gradient reduce water fluxes from vessel to tissue and reduce edema. Finally, Newton's third law explains that vitreoretinal traction decreases hydrostatic tissue pressure in the retina, increases the pressure gradient between vessel and tissue, and stimulates water fluxes from vessel into tissue, leading to edema.

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Section: How Do We Treat Edema?supporting

confidence: 38%

Section: Decreased Osmotic Pressure Gradientsupporting

confidence: 38%

Physiology of vitreous surgery

Stefánsson

2008

Graefes Arch Clin Exp Ophthalmol

256

198

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“…An increase in vitreous fluorometry values is directly associated with visual loss in well-defined cases of diabetic retinal edema. In a study using fundus photography, fluorescein angiography and vitreous fluorometry, the latter was the best predictor of visual loss in diabetic macular edema (6).…”

Section: Clinical Evaluation Of Retina Edemamentioning

confidence: 43%

Diabetic Macular Edema

Cunha‐Vaz

1998

European Journal of Ophthalmology

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Retinal edema is defined as any increase of water in retinal tissue resulting in an increase in its volume. This increase may be initially intracellular or extracellular. In the first case, there is cytotoxic edema. In the second, vasogenic edema, directly associated with an alteration of the blood-retinal barrier (BRB). Retinal thickness can now be measured, using the retinal thickness analyser (RTA). Similarly, local breakdown of the BRB can now be mapped using the retinal leakage analyser (RLA). The application of these methods to diabetic macular edema has shown that both types of retinal retinopathy edema occur in the initial stages of diabetic retinal disease. These observations suggest a role for neuroprotective and vasoprotective agents in the management of diabetic retinal disease. (Eur J Ophthalmol 1998; 8: 127-30)

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“…Two parameters were evaluated on fluorescein angiography, microaneurysms and capillary closure, according to the semiquantitative grading system [15] refered to table 1 and this only on worse eye. The evaluation was performed by a senior member who did not know to whom the angiograms belonged.…”

Section: Retinopathy Gradingmentioning

confidence: 43%

Effect of calcium dobesilate on the blood-retinal barrier in early diabetic retinopathy

et al. 1990

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The effect of calcium dobesilate on the alteration of the blood-retinal barrier was studied in 41 adult-onset, non-insulin dependent diabetic patients with minimal or no retinopathy, randomly assigned to receive either oral calcium dobesilate (1000 mg twice daily) or a placebo for 12 months. The posterior vitreous value and the penetration ratio, determined by vitreous fluorophotometry, reflected stabilisation of blood-retinal barrier permeability in the calcium dobesilate patients and deterioration of blood retinal barrier in those given placebo. During the relatively short period of the study, one year, no significant change in microaneurysm and capillary closure gradings was observed. No side effects were associated with calcium dobesilate.

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Quantification of Diabetic Macular Edema

Cited by 46 publications

References 13 publications

Physiology of vitreous surgery

Physiology of vitreous surgery

Diabetic Macular Edema

Effect of calcium dobesilate on the blood-retinal barrier in early diabetic retinopathy

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