the relationship between intraocular pressure and macular edema in patients with diabetic macular edema

Conditions: Complications of Diabetes Mellitus

Summary: the investigators propose to examine the effect of lowering the intraocular pressure on macular edema in participants diagnosed with diabetic macular edema. our theory is based on the assumption that lower intraocular pressure means higher ocular perfusion pressure, which may cause an improvement in retinal perfusion and thus an improvement in retinal oxygenation and reduced edema

ocular perfusion pressure (ocular perfusion pressure - opp), considered the driving force of ocular blood flow. perfusion pressure is defined as the difference between the artery and vein blood pressure. because ocular venous pressure is the same or slightly higher than the iop (intra ocular pressure - iop), it is common to estimate the opp as the difference between the arterial blood pressure of iop. the opp is critical for diffusion of oxygen, nutrients and metabolic waste from retinal imaging, and decrease it may reduce blood flow to the eye and lead to ischemia or hypoxia. the opp is controlled by a complex system of autoregulation. much has been written about the relationship between the opp and glaucoma, and agreed that opp is a low risk factor for this disease. diabetic macular edema (dme) is the most common cause of vision loss in developed countries the working-age. many studies were carried out in recent years in an attempt to better understand the pathophysiology of diabetic macular edema, and there is consensus in the scientific literature that hypertension have a significant effect on diabetic macular edema. this relationship is much more complex than it seems at first glance. paques and his team have shown an inverse association between blood pressure to drop night and diabetic macular edema. larsen and his team have shown a similar trend. hayreh published an article from 2007, where he described the mechanism of improvement of the diabetic macular edema with discontinuation of hypertensive treatment and thereby raising blood pressure. in this article, hayreh describes hypoxia as a significant factor in diabetic macular edema, and demonstrated that treatment of hypoxia by increasing the opp brought good results in terms of macular thickness if so, it seems that there is not only a link between levels of oxygenation of the retina to diabetic macular edema, but that improved oxygenation of the retina could lower the levels of macular edema in these patients. if a way were found to improve retinal perfusion, this may lead to an improved oxygenation and reduced edema. the investigators propose to examine the relationship between macular edema iop in participants with diabetic macular edema, thinking that high iop means lower opp, which means increased risk for developing macular edema in this participants group.

Eligibility criteria:
inclusion criteria: * participants with a diagnosis of diabetic macular edema over the age of 18 which are eligible to sign an agreement to participate in the study * presence of dme (based on clinical examination of retinal specialist + oct) in both eyes with an edema thickness ranged from 350 to 800 microns * media lucid enough to allow sufficient quality photographs by oct exclusion criteria: * patients which do not have a valid diagnosis of dme (diabetic macular edema) * patients with problems that can cause macular edema in any other: * age-related macular degeneration * central retinal vein occlusion (crvo)/branch retinal vein occlusion (brvo) /central retinal artery occlusion (crao) / branch retinal artery occlusion (brao) * epiretinal membrane (erm) or vitreo-macular traction (vmt) * patients who are pseudophakic in one eye or pseudophakic in both eyes for less than a year * patients treated in order to reduce the dme by intra-vitreal injection or by laser in the past six months * patients which are currently treat with intra ocular pressure lowering drops in at least one eye, or have been treated in the past with laser of any kind or with surgery * patients who underwent pars plana vitrectomy one or both eyes * patients who cannot undergo an oct examination * patients who want prefer to be treated by the current practices based on clinical judgment * patients with a condition that requires an intervention or laser surgery during the 3 months of study, such as active proliferative diabetic retinopathy, vitreous hemorrhage or other similar conditions

Keywords: diabetes mellitus diabetic macular edema intra ocular pressure ocular perfusion pressure retinal perfusion