In proliferative diabetic retinopathy, the Early Treatment Diabetic Retinopathy Study (ETDRS) defined clinically significant macular edema (CSME) based on which criterion?
- A Any hard exudate within the macula
- B Visual acuity worse than 6/18 with macular involvement
- C Retinal thickening at or within 500 microns of center of fovea, or hard exudates within 500 microns of center with adjacent thickening ✓
- D Retinal thickening involving one disc area within one disc diameter of fovea center
Correct answer: C. Retinal thickening at or within 500 microns of center of fovea, or hard exudates within 500 microns of center with adjacent thickening
Explanation
ETDRS defined CSME by any of three criteria: (1) retinal thickening at or within 500 microns of center of fovea; (2) hard exudates at or within 500 microns of center with adjacent retinal thickening; (3) a zone or zones of retinal thickening one disc area or larger in size within one disc diameter of center. CSME warrants focal/grid laser photocoagulation per ETDRS, though anti-VEGF (ranibizumab, aflibercept) is now preferred first-line per current guidelines. This distinction from non-CSME macular edema is critical for treatment decisions.
Reference: Khurana Comprehensive Ophthalmology, 7th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.