eMedicine Specialties > Ophthalmology > Retina

Macular Edema, Diabetic

Author: Emmanouil Mavrikakis, MD, PhD, Consultant Vitreoretinal Surgeon, Ophthalmology Department, Athens Medical Centre, Greece
Coauthor(s): Wai-Ching Lam, MD, FRCS(C), Associate Professor, Department of Ophthalmology and Vision Sciences, University of Toronto; Baseer U Khan, MD, Staff Physician, Department of Ophthalmology, University of Toronto, Canada
Contributor Information and Disclosures

Updated: Sep 29, 2009

Introduction

Background

The Early Treatment Diabetic Retinopathy Study (EDTRS) set the guidelines for the treatment of diabetic macular edema (DME). Since that time, the standard of treatment for diabetic macular edema has been glycemic control as demonstrated by the Diabetes Control and Complications Trail (DCCT), optimal blood pressure control as demonstrated by the United Kingdom Prospective Diabetes Study (UKPDS), and macular focal/grid laser photocoagulation. In EDTRS, laser photocoagulation reduced the risk of moderate visual loss from diabetic macular edema by 50% (from 24% to 12%, 3 years after initiation of treatment).1 Despite this, some patients suffer permanent visual loss even after intensive treatment. New advances in pharmacotherapy and surgical techniques have shown promise in the treatment of diabetic macular edema.

Pathophysiology

Diabetic macular edema is the result of retinal microvascular changes that occur in patients with diabetes. Thickening of the basement membrane and reduction in the number of pericytes is believed to lead to increased permeability and incompetence of retinal vasculature. This compromise of blood-retinal barrier leads to the leakage of plasma constituents in the surrounding retina, resulting in retinal edema.2 The hypoxic state achieved through this mechanism can also stimulate the production of vascular endothelial growth factor (VEGF). There is evidence that VEGF is up-regulated in diabetic macular edema and proliferative diabetic retinopathy.3

Frequency

United States

The World Health Organization (WHO) estimates that 15 million people have diabetes in the United States; half of whom are undiagnosed. In addition, about 50% of the 8 million patients diagnosed with diabetes do not receive appropriate eye care. Untreated, there is a 25-30% risk of developing clinically significant macular edema (CSME) with moderate visual loss.

International

The WHO estimates that more than 150 million people worldwide have diabetes.

Mortality/Morbidity

Diabetes is the leading cause of new blindness in the United States, to which CSME (see Physical for definition) has a significant contribution.

  • Untreated, 25-30% of patients with CSME exhibit a doubling of the visual angle within 3 years.
  • Treated, the risk drops by 50%.

Race

  • Diabetes is more common in Latinos, African Americans, and Native Americans.
  • No data describe the predilection of one racial group developing diabetic macular edema over another group.

Sex

No data describe the predilection of one sex developing diabetic macular edema over the other sex.

Age

Diabetic retinopathy, not specifically diabetic macular edema, generally occurs in persons older than 40 years. It rarely occurs before puberty.

Clinical

History

  • Ocular history
  • Diabetic history - Specific inquiry should be made into risk factors for the development of diabetic retinopathy.
    • Type of diabetes - After 20 years of disease, nearly all patients with type I and 60% of patients with type II have some degree of retinopathy.
    • Duration of the diabetes - Increased risk of diabetic retinopathy
    • Age of patient - Diabetic retinopathy is more likely to present in patients older than 40 years.
    • Diabetic control - The Diabetes Control and Complication Trial (DCCT) clearly demonstrated that tighter control of blood sugar is associated with reduced incidence of diabetic retinopathy. (Glycosylated hemoglobin [HbA1c] should be less than 7%.)
    • Renal disease - Proteinuria is a good marker for the development of diabetic retinopathy; thus, patients with diabetic nephropathy should be observed more closely.
    • Systemic hypertension - Increased risk of retinopathy (diabetic retinopathy with superimposed hypertensive retinopathy)
    • Triglycerides and lipids - Normalization of lipid levels reduces retinal leakage and exudates deposition.
    • Pregnancy - Diabetic retinopathy can progress rapidly in pregnant women, especially those with preexisting diabetic retinopathy.

Physical

Funduscopy under stereopsis and high magnification should be performed on every patient with diabetes to assess for diabetic macular edema and diabetic retinopathy. An indirect ophthalmoscope does not provide adequate magnification for the ophthalmologist to diagnose diabetic macular edema.

  • Diabetic macular edema is defined as retinal thickening within 2 disc diameters of the center of the macula.
    • Focal edema is associated with hard exudate rings resulting from leakage from microaneurysms.
    • Diffuse edema results from breakdown of blood-retinal barrier with leakage from microaneurysms, retinal capillaries, and arterioles.
  • CSME, as defined by the ETDRS, exists with any of the following findings:
    • Retinal thickening within 500 µm of the center of the fovea
    • Hard, yellow exudates within 500 µm of the center of the fovea with adjacent retinal thickening
    • At least 1 disc area of retinal thickening, any part of which is within 1 disc diameter of the center of the fovea
  • Other physical findings that should be noted include the following:
    • Visual acuity is an important parameter in following the progression of CSME, although it does not aid in the diagnosis of CSME because patients may have a visual acuity of 20/20.
    • The status of the posterior hyaloid; detached, taut, thickened

Causes

Causes include the following:

  • After 20 years of the disease, nearly all patients with type I diabetes mellitus and 60% of patients with type II diabetes mellitus will have some degree of retinopathy.
  • Poor control of blood sugar increases the risk of diabetic retinopathy.
  • Renal disease can be a marker for the development of diabetic retinopathy.
  • Systemic hypertension increases the risk of diabetic retinopathy.
  • Elevated lipid levels increase the risk of leakage and exudate deposits.

More on Macular Edema, Diabetic

Overview: Macular Edema, Diabetic
Differential Diagnoses & Workup: Macular Edema, Diabetic
Treatment & Medication: Macular Edema, Diabetic
Follow-up: Macular Edema, Diabetic
References
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References

  1. Early Treatment Diabetic Retinopathy Study Research Group. Treatment techniques and clinical guidelines for photocoagulation of diabetic macular edema. Early Treatment Diabetic Retinopathy Study Report Number 2. Early Treatment Diabetic Retinopathy Study Research Group. Ophthalmology. Jul 1987;94(7):761-74. [Medline].

  2. Albert DM, Jakobiec FA. Principles and Practice of Ophthalmology. 2nd ed. Philadelphia: WB Saunders Co; 2000.

  3. Aiello LP, Avery RL, Arrigg PG, et al. Vascular endothelial growth factor in ocular fluid of patients with diabetic retinopathy and other retinal disorders. N Engl J Med. Dec 1 1994;331(22):1480-7. [Medline].

  4. Otani T, Kishi S, Maruyama Y. Patterns of diabetic macular edema with optical coherence tomography. Am J Ophthalmol. Jun 1999;127(6):688-93. [Medline].

  5. Chew EY, Klein ML, Ferris FL 3rd, et al. Association of elevated serum lipid levels with retinal hard exudate in diabetic retinopathy. Early Treatment Diabetic Retinopathy Study (ETDRS) Report 22. Arch Ophthalmol. Sep 1996;114(9):1079-84. [Medline].

  6. Bonini-Filho MA, Jorge R, Barbosa JC, Calucci D, Cardillo JA, Costa RA. Intravitreal injection versus sub-Tenon's infusion of triamcinolone acetonide for refractory diabetic macular edema: a randomized clinical trial. Invest Ophthalmol Vis Sci. Oct 2005;46(10):3845-9. [Medline].

  7. Jonas JB, Martus P, Degenring RF, Kreissig I, Akkoyun I. Predictive factors for visual acuity after intravitreal triamcinolone treatment for diabetic macular edema. Arch Ophthalmol. Oct 2005;123(10):1338-43. [Medline].

  8. Patelli F, Fasolino G, Radice P, et al. Time course of changes in retinal thickness and visual acuity after intravitreal triamcinolone acetonide for diffuse diabetic macular edema with and without previous macular laser treatment. Retina. Oct-Nov 2005;25(7):840-5. [Medline].

  9. Avitabile T, Longo A, Reibaldi A. Intravitreal triamcinolone compared with macular laser grid photocoagulation for the treatment of cystoid macular edema. Am J Ophthalmol. Oct 2005;140(4):695-702. [Medline].

  10. Cunningham ET Jr, Adamis AP, Altaweel M, et al. A phase II randomized double-masked trial of pegaptanib, an anti-vascular endothelial growth factor aptamer, for diabetic macular edema. Ophthalmology. Oct 2005;112(10):1747-57. [Medline].

  11. Scott IU, Edwards AR, Beck RW, et al. A phase II randomized clinical trial of intravitreal bevacizumab for diabetic macular edema. Ophthalmology. Oct 2007;114(10):1860-7. [Medline].

  12. Hsu J. Drug delivery methods for posterior segment disease. Curr Opin Ophthalmol. May 2007;18(3):235-9. [Medline].

  13. Diabetic Retinopathy Clinical Research Network. A randomized trial comparing intravitreal triamcinolone acetonide and focal/grid photocoagulation for diabetic macular edema. Ophthalmology. Sep 2008;115(9):1447-9, 1449.e1-10. [Medline].

  14. Lewis H, Abrams GW, Blumenkranz MS, Campo RV. Vitrectomy for diabetic macular traction and edema associated with posterior hyaloidal traction. Ophthalmology. May 1992;99(5):753-9. [Medline].

  15. Tachi N, Ogino N. Vitrectomy for diffuse macular edema in cases of diabetic retinopathy. Am J Ophthalmol. Aug 1996;122(2):258-60. [Medline].

  16. Fong DS, Segal PP, Myers F, Ferris FL, Hubbard LD, Davis MD. Subretinal fibrosis in diabetic macular edema. ETDRS report 23. Early Treatment Diabetic Retinopathy Study Research Group. Arch Ophthalmol. Jul 1997;115(7):873-7. [Medline].

  17. Takagi H, Otani A, Kiryu J, Ogura Y. New surgical approach for removing massive foveal hard exudates in diabetic macular edema. Ophthalmology. Feb 1999;106(2):249-56; discussion 256-7. [Medline].

  18. Kertes. Clinical Trials in Ophthalmology: Summary and Practice Guide. Lippincott Williams & Wilkins; 1998:15-35.

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Further Reading

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Keywords

diabetic macular edema, DME, diabetes, diabetic eye disease, diabetic eye complications, diabetic retinopathy, DR, retinal edema, macula

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Contributor Information and Disclosures

Author

Emmanouil Mavrikakis, MD, PhD, Consultant Vitreoretinal Surgeon, Ophthalmology Department, Athens Medical Centre, Greece
Emmanouil Mavrikakis, MD, PhD is a member of the following medical societies: American Academy of Ophthalmology and American Society of Retina Specialists
Disclosure: Nothing to disclose.

Coauthor(s)

Wai-Ching Lam, MD, FRCS(C), Associate Professor, Department of Ophthalmology and Vision Sciences, University of Toronto
Wai-Ching Lam, MD, FRCS(C) is a member of the following medical societies: American Academy of Ophthalmology, Canadian Ophthalmological Society, and Royal College of Physicians and Surgeons of Canada
Disclosure: Pfizer Grant/research funds Primary investigator; Novartis Honoraria Speaking and teaching; Novartis Honoraria Review panel membership

Baseer U Khan, MD, Staff Physician, Department of Ophthalmology, University of Toronto, Canada
Baseer U Khan, MD is a member of the following medical societies: Canadian Ophthalmological Society
Disclosure: Nothing to disclose.

Medical Editor

V Al Pakalnis, MD, PhD, Professor of Ophthalmology, University of South Carolina School of Medicine; Chief of Ophthalmology, Dorn Veterans Affairs Medical Center
V Al Pakalnis, MD, PhD is a member of the following medical societies: American Academy of Ophthalmology, American College of Surgeons, and South Carolina Medical Association
Disclosure: Nothing to disclose.

Pharmacy Editor

Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: eMedicine Salary Employment

Managing Editor

Steve Charles, MD, Director of Charles Retina Institute; Clinical Professor, Department of Ophthalmology, University of Tennessee College of Medicine; Adjunct Professor of Ophthalmology, Columbia College of Physicians & Surgeons; Clinical Professor Ophthalmology, Chinese University of Hong Kong
Steve Charles, MD is a member of the following medical societies: American Academy of Ophthalmology, American Society of Retina Specialists, Club Jules Gonin, Macula Society, and Retina Society
Disclosure: Alcon Laboratories Consulting fee Consulting; OptiMedica Ownership interest Consulting

CME Editor

Lance L Brown, OD, MD, Ophthalmologist, Affiliated With Freeman Hospital and St John's Hospital, Regional Eye Center, Joplin, Missouri
Disclosure: Nothing to disclose.

Chief Editor

Hampton Roy Sr, MD, Associate Clinical Professor, Department of Ophthalmology, University of Arkansas for Medical Sciences
Hampton Roy Sr, MD is a member of the following medical societies: American Academy of Ophthalmology, American College of Surgeons, and Pan-American Association of Ophthalmology
Disclosure: Nothing to disclose.

 
 
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