diabetic%20retinopathy
DIABETIC RETINOPATHY
Treatment Guideline Chart
Diabetic retinopathy is an abnormality of the microvasculature of the retina that occurs to almost all patients with chronic diabetes mellitus.
It is one of the leading cause of blindness worldwide and principal cause of impaired vision in patients aged 25-75 years of age.
The abnormality causes microaneurysms, retinal hemorrhages, lipid exudates, macular edema & neovascular vessel growth that may lead to blindness.

Diabetic%20retinopathy Diagnosis

Classification

Types of Diabetic Retinopathy (DR)

  • Nonproliferative DR (NPDR)
    • Earliest clinically apparent stage of DR
    • Characterized by abnormalities primarily in the posterior retina and macula consisting of:
      • Microvascular abnormalities (eg microaneurysms, occluded vessels and dilated/tortuous vessels)
      • Intraretinal hemorrhages
      • Nerve-fiber layer infarcts (cotton-wool spots)
      • Hard exudates
    • Visual loss is primarily caused by macular edema
    • As the disease progresses, gradual closure of the retinal vessels occur that eventually results to impaired perfusion and retinal ischemia manifested as:
      • Venous abnormalities (eg beading, dilation, loops)
      • Increasing retinal hemorrhages
      • IRMA
      • Increasing exudation
  • Proliferative DR (PDR)
    • Most advanced stage of DR
    • Onset of neovascularization of the inner surface of the retina that is induced by retinal ischemia
    • Neovascularization (NVD and NVE) causes preretinal and vitreous hemorrhage, subsequent fibrosis and traction retinal detachment
    • May develop from existing severe NPDR or without substantial NPDR

Diabetic Retinopathy Disease Severity Level based on Findings upon Dilated Ophthalmoscopy1

  • No apparent retinopathy
    • No abnormalities observed
  • Mild NPDR
    • Have microaneurysms only
  • Moderate NPDR
    • Presence of microaneurysms and other signs (eg hard exudates, cotton wool spots, dot and blot hemorrhages) but less than severe NPDR
  • Severe NPDR have any of the following but with no signs of proliferative retinopathy:
    • ≥20 intraretinal hemorrhages in each of 4 quadrants
    • Definite venous beading in ≥2 quadrants
    • Prominent IRMA in ≥1 quadrant
  • Non-high-risk PDR
    • Presents with  neovascularization and/or vitreous/preretinal hemorrhage but does not meet the criteria for high-risk PDR
  • High-risk PDR
    • Have neovascularization within 1 disc diameter of the optic nerve head that are ≥¼-⅓ disc area with or without vitreous or preretinal hemorrhage or
    • Vitreous and/or preretinal hemorrhage associated with less extensive NVD or with NVE ≥½ disc area in size

Diabetic Macular Edema (DME)

  • Thickening located within 2 disc diameters of the center of the macula
  • Occurs at any stage of DR and can run an independent course
  • Recommended to be evaluated through dilated examination using slit-lamp biomicroscopy, OCT, and/or stereoscopic fundus photography
  • Classified into noncenter-involved or center-involved macular edema
  • Severity of DME can help determine the appropriate treatment modality to give the patient and follow-up recommendations

DME Severity Scale based on Observation upon Dilated Ophthalmoscopy1

  • No macular edema if there is no retinal thickening or hard exudates in the posterior pole
  • Mild DME if the retinal thickening or hard exudates in the posterior pole is distant from the center of the macula
  • Moderate or noncentral-involved DME if the retinal thickening or hard exudates approaches the center of the macula but does not involve the center that is 1 mm in diameter
  • Severe or central-involved DME if the retinal thickening or hard exudates involves the center of the macula that is 1 mm in diameter

Clinically Significant Macular Edema (CSME)

  • May occur at any stage of DR and defined to include any 1 of the following features:
    • Retinal thickening at or within 500 microns of the center of the macula (approximately ½ optic disc diameter)
    • Hard exudates at or within 500 microns of the center of the macula, if associated with thickening of the adjacent retina
    • Retinal thickening zone or zones of ≥1 disc area in size, any part of which is within 1 disc diameter of the center of the macula
  • Helps in differentiating different types of DR

1 Modified from: Wilkinson CP, Ferris FL III, Klen RE, et al. Proposed international clinical diabetic retinopathy and diabetic macular edema disease severity scales. Ophthalmology. 2003;110:1679-1680.
International Council of Ophthalmology. Updated 2017 ICO guidelines for diabetic eye care. http://www.icoph.org/. Jan 2017.

History

  • Chronic DM especially when it is uncontrolled
  • Non-compliance to antidiabetic medications
  • Poor glycemic control (HbA1c level)
  • Medical history (eg obesity, renal disease, hypertension)
  • Ocular history (eg ocular injections, trauma, surgery)

Ocular Exams

  • Visual acuity determines the extent of effect in the central vision
  • Slit-lamp biomicroscopy examines the posterior pole and midperipheral posterior pole, and assesses the presence and severity of DR
  • Intraocular pressure determines the presence of glaucoma
  • Gonioscopy detects anterior chamber neovascularization if there is iris neovascularization or elevated IOP
  • Dilated fundoscopy including stereoscopic examination of the posterior pole
    • 0.5-1% Tropicamide and/or 2.5% Phenylephrine use in pupil dilation is safe and markedly increases the sensitivity of DR screening

Ancillary Ophthalmological Exams

  • Fluorescein angiography
    • Evaluates the cause of unexplained decrease of visual acuity (eg macular capillary non-perfusion, capillary leakage that leads to macular edema) and guides in treating clinically significant macular edema (CSME)
      • May be used to help evaluate retinal non-perfusion area, presence of retinal neovascularization and microaneurysms or macular capillary non-perfusion in diabetic macular edema (DME)
    • May be used to differentiate intraretinal microvascular abnormalities from new blood vessels observed in proliferative DR
    • May occasionally be used to assess patients with questionable or difficult examinations for DME 
    • Improves detection of peripheral ischemia and peripheral lesions that are not clinically apparent
  • Color fundus photography
    • Preferred tool for retinopathy assessment
      • Creates a permanent record of retinal assessment
    • Considered as the most effective screening tool for DR 
    • Documents the status of the retina if surgery is not performed, progression of the disease and response to treatment
  • Optical coherence tomography (OCT)
    • Most sensitive tool to identify and assess DME
    • Produces high-resolution image of the vitreoretinal interface, neurosensory retina and subretinal space
    • Used to quantify macular thickness and determine severity of DME, monitor resolution of macular edema and identify vitreo-macular traction in patients with DME
    • May be used to assess unexplained loss of visual acuity, evaluate patients with questionable or difficult examinations for DME, investigate other causes of macular edema or screen patients with minimal or without DR
    • May be used to evaluate the necessity for repeat anti-VEGF treatment, change in therapeutic agent, start of laser treatment or perform vitrectomy
  • OCT angiography (OCTA)
    • Provides quantitative assessment of macular ischemia
      • Able to quantify regions of macular nonperfusion, identify retinal neovascular tissue and detect preclinical microvascular alterations
    • Major advantages include non-invasiveness of the procedure and the ability to visualize depth-resolved, capillary-level abnormalities in the 3 retinal plexuses
  • Ultrasonography
    • May be used to evaluate the amount of vitreous hemorrhage, define the extent and severity of vitreoretinal traction and detect retinal detachments in the setting of media opacity
    • Detects retinal detachment in diabetic eyes with cataract or vitreous hemorrhage

Laboratory Tests

Ancillary Laboratory Exam

  • Fasting blood sugar (FBS) and/or oral glucose tolerance test (OGTT) assess the severity of DM
  • Glycosylated hemoglobin (HbA1c) assesses past glycemic control

Screening

  • Regular eye exam for diabetic retinopathy should be done in all patients with diabetes mellitus with the following recommended schedule:
    • Adult with type 1 DM should have the first eye exam at 3-5 years after onset of disease then yearly thereafter
    • Adult with type 2 DM should have the first eye exam at the time of diagnosis of DM then with yearly follow-up
    • Pregnant patients prior to conception or early in the 1st trimester should have eye screening for DR with follow-up every 3-12 months for those with no retinopathy or mild to moderate NPDR and every 1-3 months follow-up for those with severe NPDR or worse
    • Children with type 1 DM with 5-yr history first eye exam at 9 years old and those with 2 years history have it at 12 years old then yearly follow-up
    • Children with type 2 DM first eye exam at the time of diagnosis then yearly follow-up
  • Abnormal findings may require frequent follow-up exams

Level of urgency of referral criteria:

  • Within 4 weeks referral is advised if there are:
    • Unexplained drop in visual acuity
    • Hard exudates within 1 disc diameter of the fovea
    • Diabetic macular edema (DME)
    • Pre-proliferative or moderate NPDR
  • Within 1 week referral is advised if the following are present:
    • New vessels
    • Preretinal hemorrhages
    • Vitreous hemorrhage
    • Rubeosis iridis
  • Emergency referral within the day should be done when the following are found:
    • Sudden, severe visual loss or symptoms or
    • Signs suggesting retinal detachment
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