title: Diabetic macular edema: what is focal and what is diffuse?
abstract: OBJECTIVE
  To review the available information on classification of diabetic macular edema (DME) as focal or diffuse.
  
  
  METHODS
  Interpretive essay.
  
  
  METHODS
  Literature review and interpretation.
  
  
  RESULTS
  The terms focal diabetic macular edema and diffuse diabetic macular edema frequently are used without clear definitions. Published definitions often use different examination methods and often are inconsistent. Evaluating published information on the prevalence of focal and diffuse DME, the responses of focal and diffuse DME to treatments, and the importance of focal and diffuse DME in assessing prognosis is hindered because the terms are used inconsistently. A newer vocabulary may be more constructive, one that describes discrete components of the concepts such as extent and location of macular thickening, involvement of the center of the macula, quantity and pattern of lipid exudates, source of fluorescein leakage, and regional variation in macular thickening and that distinguishes these terms from the use of the term focal when describing one type of photocoagulation technique. Developing methods for assessing component variables that can be used in clinical practice and establishing reproducibility of the methods are important tasks.
  
  
  CONCLUSIONS
  Little evidence exists that characteristics of DME described by the terms focal and diffuse help to explain variation in visual acuity or response to treatment. It is unresolved whether a concept of focal and diffuse DME will prove clinically useful despite frequent use of the terms when describing management of DME. Further studies to address the issues are needed.
authors.affiliation: Jaeb Center for Health Research, Tampa, FL 33647, USA. DRCR.netX4@jaeb.org
authors.forename: David J
authors.initials: DJ
authors.lastname: Browning
authors.forename: Michael M
authors.initials: MM
authors.lastname: Altaweel
authors.forename: Neil M
authors.initials: NM
authors.lastname: Bressler
authors.forename: Susan B
authors.initials: SB
authors.lastname: Bressler
authors.forename: Ingrid U
authors.initials: IU
authors.lastname: Scott
mesh_terms: D003930:Diabetic Retinopathy / Q000145:classification* / Q000175:diagnosis / Q000503:physiopathology; D005451:Fluorescein Angiography; D005654:Fundus Oculi; D006801:Humans; D008269:Macular Edema / Q000145:classification* / Q000175:diagnosis / Q000503:physiopathology; D009626:Terminology as Topic; D041623:Tomography, Optical Coherence
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