The Drop That Dried the Macula but Missed on Vision: DIAMOND-1/2 and OCS-01

Can a drop replace the needle in diabetic macular edema? Dr. Veeral Sheth returns to Retina Synthesis to walk through DIAMOND-1 and DIAMOND-2, Oculis's twin Phase 3 trials of OCS-01, a high-concentration (15 mg/mL) topical dexamethasone formulated to reach the posterior segment. Across 800+ patients with mild-to-moderate DME, the drop did what it was supposed to do anatomically — central thickness fell quickly and stayed down for 52 weeks — yet both trials missed the week-52 visual acuity endpoint, with the vehicle arm gaining an unexpected +5 letters (+1.0 and +4.6 letters on OCS-01 vs. +5.0 on vehicle). Dr. Sheth, who served on the DIAMOND program committee, discusses why the vehicle group did so well (trial participation, glycemic control, dry-eye effects), why the steroid arm may have underperformed (a largely phakic population, steroid cataract and IOP signals, unmeasured adherence to a six-times-daily regimen), and why Oculis will not file for approval in DME. He also makes the case that topical steroids still have a role — as a pre-injection bridge for needle-averse patients, around cataract surgery, and as an adjunct — and shares his current DME algorithm: declare anti-VEGF response within three months, then pivot early to dexamethasone implants or sub-Tenon's triamcinolone.