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DIABETIC RETINOPATHY

Results 1-3 of 3
   
Non-Proliferative Diabetic Retinopathy  
 

Diabetes is a worldwide epidemic disease. In recent decades it has progressed from a disease affecting people primarily in developed...

Diabetes is a worldwide epidemic disease. In recent decades it has progressed from a disease affecting people primarily in developed countries, to a global phenomenon. Today diabetic retinopathy is a major cause of blindness in adult patients.

The eye is one of the target organs of this multisystemic disease. Diabetic retinopathy is nothing more than a compromise of the retinal microcirculation. The chronic exposure to hyperglycemia determines a number of biochemical and consequently histological changes

Initially, selective loss of pericytes, basement membrane thickening, as well as a diverse number of hematologic abnormalities, generate capillary occlusion, microaneurysm formation, dilation and beading of retinal veins, as well as retinal ischemia.

A compromise of the endothelial barrier function allows vascular leakage, originating retinal edema and deposition of hard exsudates. Areas of retinal ischemia generate vasoproliferative factors (mainly vascular endothelium growth factor - VEGF) that later stimulate the growth of neovessels.

According to fundoscopic findings, diabetic retinopathy may be divided in non-proliferative and proliferative diabetic retinopathy, based on the presence of neovascularization. The most commonly used classification scale is the International Clinical Diabetic Retinopathy Disease Severity Scale:

No apparent retinopathy: no abnormalities

   Mild Non-proliferative Diabetic Retinopathy (NPDR): microaneurysms only

   Moderate NPDR: more than just microaneurysms but less than severe NPDR

   Severe NPDR:

                Any of the following:

                               •More than 20 intraretinal hemorrhages in each of 4 quadrants

                               •Definite venous beading in 2 or more quadrants

                               •Prominent intraretinal microvascular abnormalities (IRMA) in at least one

                               quadrant

                               And no signs of proliferative retinopathy

   Proliferative Diabetic retinopathy (PDR):

                One or more of the following:

                               • Neovascularization

                               •Vitreous/Preretinal hemorrhage

Panretinal photocoagulation (PRP) is the gold standard treatment for patients with severe NPDR and PDR. Laser photocoagulation aims to destroy the ischemic areas of the retina and to reduce the production of vasoproliferative factors. It is however associated with significant side effects such as: visual field loss, dischromatopsia and decreased night vision. It may also exacerbate a macular edema. Therefore, PRP should be judiciously used and macular edema addressed prior to PRP (see below).

Diabetic macular edema is a serious complication of the increased vascular permeability. It can be characterized clinically as focal, multifocal and diffuse. The concept of clinically significant macular edema (CSME) was first introduced in the Early Treatment Diabetic Retinopathy Study (ETDRS). CSME was defined as retinal edema located at or within 500 µm of the center of the macula, hard exsudates at or within 500 µm of the center of the macula if associated with thickening of the adjacent retina or a zone of thickening larger than 1 disc area if located within 1 disc diameter of the center of the macula. ETDRS trial found a better visual outcome for patients with CSME submitted to focal laser (50% of risk reduction in doubling the visual angle). Anti-VEGF agents have also been progressively used to treat CSME. CMSE can be exacerbated by PRP or cataract surgery and therefore, its treatment should take precedence.

Ischemic maculopathy is characterized by an increase in diameter of the foveal avascular zone as well as an irregularity of its limits. Fluorescein angiography allows the definitive diagnosis. There is no proven treatment for ischemic maculopathy.

Proliferative Diabetic Retinopathy in Type 1 Diabetes  
 

Diabetes is a worldwide epidemic disease. In recent decades it has progressed from a disease affecting people primarily in developed...

Diabetes is a worldwide epidemic disease. In recent decades it has progressed from a disease affecting people primarily in developed countries, to a global phenomenon. Today diabetic retinopathy is a major cause of blindness in adult patients.

The eye is one of the target organs of this multisystemic disease. Diabetic retinopathy is nothing more than a compromise of the retinal microcirculation. The chronic exposure to hyperglycemia determines a number of biochemical and consequently histological changes

Initially, selective loss of pericytes, basement membrane thickening, as well as a diverse number of hematologic abnormalities, generate capillary occlusion, microaneurysm formation, dilation and beading of retinal veins as well as retinal ischemia.

A compromise of the endothelial barrier function allows vascular leakage, originating retinal edema and deposition of hard exsudates. Areas of retinal ischemia generate vasoproliferative factors (mainly vascular endothelium growth factor - VEGF) that later stimulate the growth of neovessels.

According to fundoscopic findings, diabetic retinopathy may be divided in non-proliferative and proliferative diabetic retinopathy, based on the presence of neovascularization. The most commonly used classification scale is the International Clinical Diabetic Retinopathy Disease Severity Scale:

No apparent retinopathy: no abnormalities

   Mild Non-proliferative Diabetic Retinopathy (NPDR): microaneurysms only

   Moderate NPDR: more than just microaneurysms but less than severe NPDR

   Severe NPDR:

                Any of the following:

                               •More than 20 intraretinal hemorrhages in each of 4 quadrants

                               •Definite venous beading in 2 or more quadrants

                               •Prominent intraretinal microvascular abnormalities (IRMA) in at least one quadrant

                And no signs of proliferative retinopathy

   Proliferative Diabetic retinopathy (PDR):

                One or more of the following:

                               •Neovascularization

                               •Vitreous/Preretinal hemorrhage

Neovessels in PDR are first intra-retinal with minimal fibrosis. After this initial phase they cross the internal limiting membrane (ILM), and migrate to the vitreous body, using it as a substrate for further growth. These vessels are accompanied by fibrotic changes, forming pre-retinal membranes, usually along the vascular arcades. The final stage is characterized by an involution of the vascular component and contraction of the fibrotic membranes. During this cycle, several complications may arise.

PDR can be stratified according to the Diabetic Retinopathy Study. High risk PDR was defined as any one of the following:

                •Mild neovessels in the optic disc (NVD) when associated with vitreous hemorrhage

                •Moderate to severe NVD (1/4 to 1/3 of the optic disc area), with or without vitreous hemorrhage

                •Moderate neovessels elsewhere (NVE) (1/2 the optic disc area), with vitreous hemorrhage. Treatment should be prompt in this group of patients given the high risk of severe visual loss.

Medical management plays a primordial role in PDR. Optimal glycemic (glycosylated hemoglobin - HbA1c < 7%) and blood pressure control are paramount to a good outcome.

Panretinal photocoagulation (PRP) is the gold standard for patients with severe NPDR and PDR. Laser photocoagulation aims to destroy the ischemic areas of the retina and reduce the production of vasoproliferative factors. Scatter laser should be avoided in areas of vitreo-retinal traction and prominent fibrovascular membranes since it can determine their contraction and subsequent retinal detachment.

Vitreous hemorrhage is a common occurrence in diabetic patients and frequently heralds the diagnosis of PDR. Blood in the vitreous cavity and its degradation products such as hemosiderin are toxic to retinal structures. A balance should be struck between a conservative attitude, observing the patient regularly and surgical intervention with pars plana vitrectomy (PPV). The Diabetic Retinopathy Vitrectomy Study (DRVS), published in 1985, demonstrated a superiority of early (1-6 months) surgery when compared to late surgery ( > 1 year) in patients with diabetes type 1. This benefit was not conclusively found for type 2 diabetics. Given the advances in vitreoretinal surgery in the last decades we feel inclined to recommend an earlier intervention. This should be more urgent in patients with type 1 diabetes, patients never submitted to laser photocoagulation, patients with serious diabetic retinopathy in the fellow eye, and patients not likely to comply with a regular follow-up. Intraoperatively, after vitrectomy, a thorough PRP with endolaser up to the ora serrata should be performed.

One particular entity that demands prompt surgical intervention is pre-macular, retro-hyaloid hemorrhage. A PPV, with induction of posterior vitreous detachment (PVD) and clearance of the pre-retinal blood avoids fibrosis and a subsequent dismal visual prognosis.

Current indications for PPV in diabetic patients include:

                •Dense, nonclearing vitreous hemorrhage

                •Tractional retinal detachment involving or threatening the macula

                •Combined traction and rhegmatogenous retinal detachment

                •Diffuse macular edema associated with a taut posterior hyaloid

                •Significant recurrent vitreous hemorrhage despite maximal PRP

Proliferative Diabetic Retinopathy inType 2 Diabetes  
 

Diabetes is a worldwide epidemic. In recent decades it has progressed from a disease affecting people primarily in developed countries,...

Diabetes is a worldwide epidemic. In recent decades it has progressed from a disease affecting people primarily in developed countries, to a global phenomenon. Today diabetic retinopathy is a major cause of blindness in adult patients.

The eye is one of the target organs of this multisystemic disease. Diabetic retinopathy is nothing more than a compromise of the retinal microcirculation. The chronic exposure to hyperglycemia determines a number of biochemical and consequently histological changes

Initially, selective loss of pericytes, basement membrane thickening, as well as a diverse number of hematologic abnormalities, generate capillary occlusion, microaneurysm formation, dilation and beading of retinal veins as well as retinal ischemia.

A compromise of the endothelial barrier function allows vascular leakage, originating retinal edema and deposition of hard exsudates. Areas of retinal ischemia generate vasoproliferative factors (mainly vascular endothelium growth factor – VEGF) that later stimulate the growth of neovessels.

According to fundoscopic findings, diabetic retinopathy may be divided in non-proliferative and proliferative diabetic retinopathy, based on the presence of neovascularization. The most commonly used classification scale is the International Clinical Diabetic Retinopathy Disease Severity Scale:

No apparent retinopathy: no abnormalities

   Mild Non-proliferative Diabetic Retinopathy (NPDR): microaneurysms only

   Moderate NPDR: more than just microaneurysms but less than severe NPDR

   Severe NPDR:

                Any of the following:

                               •More than 20 intraretinal hemorrhages in each of 4 quadrants

                               •Definite venous beading in 2 or more quadrants

                               •Prominent intraretinal microvascular abnormalities (IRMA) in at least one quadrant

                And no signs of proliferative retinopathy

Proliferative Diabetic retinopathy (PDR):

                One or more of the following:

                               •Neovascularization

                               •Vitreous/Preretinal hemorrhage

Neovessels in PDR are first intra-retinal with minimal fibrosis. After this initial phase they cross the internal limiting membrane (ILM), and migrate to the vitreous body, using it as substrate for further growth. These vessels are accompanied by fibrotic changes, forming pre-retinal membranes, usually along the vascular arcades. The final stage is characterized by an involution of the vascular component and contraction of the fibrotic membranes. During this cycle, several complications may arise.

PDR can be stratified according to the Diabetic Retinopathy Study. High risk PDR was defined as any one of the following:

                •Mild neovessels in the optic disc (NVD) when associated with vitreous hemorrhage

                •Moderate to severe NVD (1/4 to 1/3 of the optic disc area), with or without vitreous hemorrhage

                •Moderate neovessels elsewhere (NVE) (1/2 the optic disc area), with vitreous hemorrhage. Treatment should be prompt in this group of patients given the high risk of severe visual loss.

Medical management plays a primordial role in PDR. Optimal glycemic (glycosylated hemoglobin – HbA1c < 7%) and blood pressure control are paramount to a good outcome.

Panretinal photocoagulation (PRP) is the gold standard for patients with severe NPDR and PDR. Laser photocoagulation aims to destroy the ischemic areas of the retina and reduce the production of vasoproliferative factors. Scatter laser should be avoided in areas of vitreo-retinal traction and prominent fibrovascular membranes since it can determine their contraction and subsequent retinal detachment.

Vitreous hemorrhage is a common occurrence in diabetic patients and frequently heralds the diagnosis of PDR. Blood in the vitreous cavity and its degradation products such as hemosiderin are toxic to retinal structures. A balance should be struck between a conservative attitude, observing the patient regularly and surgical intervention with pars plana vitrectomy (PPV). The Diabetic Retinopathy Vitrectomy Study (DRVS) published in 1985 demonstrated a superiority of early (1-6 months) surgery, when compared to late surgery ( > 1 year) in patients with diabetes type 1. This benefit was not conclusively found for type 2 diabetics. Given the advances in vitreoretinal surgery in the last decades we feel inclined to recommend an earlier intervention that should be made more urgent in patients with type 1 diabetes, patients never submitted to laser photocoagulation, patients with serious diabetic retinopathy in the fellow eye and patients not likely to comply with a regular follow-up regimen. Intraoperatively, after vitrectomy a thorough PRP with endolaser up to the ora serrata should be performed.

One particular entity that demands prompt surgical intervention is pre-macular, retro-hyaloid hemorrhage. A PPV, with induction of posterior vitreous detachment (PVD) and clearance of the pre-retinal blood avoids fibrosis and a subsequent dismal visual prognosis.

Current indications for PPV in diabetic patients include:

  • Dense, nonclearing vitreous hemorrhage
  • Tractional retinal detachment involving or threatening the macula
  • Combined tractional and rhegmatogenous retinal detachment
  • Diffuse macular edema associated with taut posterior hyaloids
  • Significant recurrent vitreous hemorrhage despite maximal PRP