According to the ETDRS (Early Treatment Diabetic Retinopathy Study), the threshold for treating clinically significant macular edema (CSME) with laser photocoagulation is defined by which criterion?
- A Any macular edema visible on biomicroscopy regardless of location
- B Retinal thickening only when visual acuity is reduced to 6/12 or less
- C Retinal thickening within 500 μm of the center of the fovea, OR hard exudates within 500 μm of center with adjacent thickening, OR retinal thickening ≥1 disc area within 1 disc diameter of the foveal center ✓
- D Presence of hard exudates anywhere within the posterior pole
Correct answer: C. Retinal thickening within 500 μm of the center of the fovea, OR hard exudates within 500 μm of center with adjacent thickening, OR retinal thickening ≥1 disc area within 1 disc diameter of the foveal center
Explanation
CSME as defined by ETDRS includes any one of three criteria: retinal thickening within 500 μm of the foveal center; hard exudates within 500 μm of the foveal center with adjacent retinal thickening; or a zone of retinal thickening ≥1 disc area located within 1 disc diameter of the foveal center. Treatment is indicated regardless of visual acuity. Currently, anti-VEGF therapy has largely superseded focal laser for center-involving CSME, but the ETDRS definition remains standard in examinations.
Reference: Khurana Comprehensive Ophthalmology, 7th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.