diabetic retinopathy and maculopathy management

Anti-vascular endothelial growth factor (anti-VEGF): Substances that inhibit the action of vascular endothelial growth factor protein.

Clinically significant macular edema (CSME): Retinal thickening at or within 500 µm of the center of the macula; and/or hard exudates at or within 500 µm of the center of the macula, if associated with thickening of the adjacent retina; and/or a zone or zones of retinal thickening 1 disc area in size, any part of which is within 1 disc diameter of the center of the macula.

Diabetes mellitus: According to the American Diabetes Association Expert Committee on the Diagnosis and Classification of Diabetes Mellitus, the criteria for the diagnosis of diabetes mellitus are as follows.

·        Fasting plasma glucose equal to or exceeding 126 mg/dL (7.0 mmol/L). Fasting is defined as no caloric intake for at least 8 hours.

or

·        Symptoms of hyperglycemia and a casual plasma glucose concentration equal to or exceeding 200 mg/dL (11.1 mmol/L). “Casual” is defined as any time of day without regard to time since last meal. The classic symptoms of hyperglycemia include polyuria, polydipsia, and unexplained weight loss. or

·        A plasma glucose measurement at 2 hours postload equal to or exceeding 200 mg/dL (11.1 mmol/L) during an oral glucose tolerance test. The test should be performed as described by the World Health Organization, using a glucose load containing the equivalent of 75 g anhydrous glucose dissolved in water. However, the expert committee has recommended against oral glucose tolerance testing for routine clinical use. (Source: Report of the Expert Committee on the Diagnosis and Classification of Diabetes Mellitus. Diabetes Care 2008;31 (suppl):55-60.)

Diabetic macular edema: The accumulation of fluid in the macula due to leaky blood vessels.

Early proliferative diabetic retinopathy (i.e., proliferative retinopathy without DRS high-risk characteristics): New vessels that do not meet the criteria of high-risk proliferative retinopathy.

Focal photocoagulation: A laser technique directed to abnormal blood vessels with specific areas of focal leakage (i.e., microaneurysms) to reduce chronic fluid leakage in patients with macular edema.

Grid photocoagulation: A laser technique in which a grid pattern of scatter burns is applied in areas of diffuse macular edema and nonperfusion. Typically, fluorescein angiograms of these areas show a diffuse pattern rather than focal leakage.

High-risk proliferative diabetic retinopathy: New vessels on or within 1 disc diameter of the optic disc about one-quarter to one-third disc area, with or without vitreous or preretinal hemorrhage; or vitreous and/or preretinal hemorrhage accompanied by new vessels either on the optic disc less than ¼ disc area, or new vessels elsewhere equaling or exceeding one-quarter disc area.  

Intraretinal microvascular abnormalities: Tortuous intraretinal vascular segments, varying in caliber from barely visible to 31 µm in diameter (one-quarter the width of a major vein at the disc margin); they occasionally can be larger. Intraretinal microvascular abnormalities may be difficult to distinguish from neovascularization.

Macular edema: Thickening of the retina within 1 or 2 disc diameters of the center of the macula. (See Clinically significant macular edema.) Any other thickening of the macula not within this area is non-CSME.

Mild nonproliferative diabetic retinopathy: At least 1 microaneurysm and less than moderate nonproliferative diabetic retinopathy.

Moderate nonproliferative diabetic retinopathy: Hemorrhages and/or microaneurysms greater than standard photograph 2A, and/or soft exudates, venous beading, or IRMA present but less than severe nonproliferative retinopathy.

Moderate visual loss: The loss of 15 or more letters on the ETDRS visual acuity chart, or doubling of the visual angle (e.g., 6/6 to 6/12 etc.).

New vessels at the optic disc: New vessels at the optic disc; neovascularization on or within 1 disc diameter of the optic disc.

New vessels elsewhere in the retina: New vessels elsewhere in the retina; neovascularization elsewhere in the retina and greater than 1 disc diameter from the optic disc margin.

New vessels on the iris: New vessels on the iris; neovascularization of the iris.

Nonproliferative diabetic retinopathy: The phases of diabetic retinopathy with no evidence of retinal neovascularization.

Optical coherence tomography: A diagnostic test using low energy lasers that takes a cross-section image of the retina, Used mostly to determine if there are membranes on the surface of the macula or fluid within or beneath it. 

Panretinal photocoagulation: A type of laser surgery used for patients with PDR. The surgery is delivered in a scatter pattern throughout the peripheral fundus and is intended to lead to a regression of neovascularization.

Proliferative diabetic retinopathy: Advanced disease characterized by NVD and/or new vessels elsewhere in the retina.

Retinal hard exudate: Protein and lipid accumulation within the retina.

Refractory DME: in which the patient received 3 monthly doses of antiVEGF with poor anatomical and functional response.

Scatter photocoagulation: See Panretinal photocoagulation.

Severe nonproliferative diabetic retinopathy: Using the 4-2-1 rule, the presence of at least one of the following features: (1) severe intraretinal hemorrhages and microaneurysms, in 4 quadrants; (2) venous beading in 2 or more quadrants; or (3) moderate IRMA in 1 or more quadrants.

Severe visual loss: Occurrence of visual acuity worse than 5/200 at any two consecutive visits scheduled at 4-month intervals.