Macular edema resolution assessment with implantable dexamethasone in diabetic retinopathy (MERIT): a pilot study

This study aimed to evaluate the effect of dexamethasone implantation on the hard exudates (HEX) in patients with diabetic macular edema (DME).

This was a nonrandomized open-label single-center prospective trial.

This study included 15 eyes of 11 subjects with DME. Key inclusion criteria were naïve eyes with DME with HEX within 3 mm of fovea with center-involving DME; central macular thickness (CMT) >250 μm at baseline; best-corrected visual acuity (BCVA) between 20/400 and 20/40. Key exclusion criteria were previous intraocular surgery and history of panretinal photocoagulation (PRP) in past 4 months. The primary outcome measure was change in total HEX area at the macula (in mm²) measured by semiautomated algorithm. Secondary outcome measures were change in visual acuity, low-contrast visual acuity (LCVA), retinal sensitivity (RS) on macular microperimetry, and CMT.

The total HEX area reduced from 1.5 mm² (±1.46 mm²) at baseline to 0.89 mm² (±1.062 mm²) at the final visit (p=0.185). The CMT improved significantly (p=0.03) from 488.67 μm (±240.66 μm) to 326.93 μm (±135.84 μm) at the final visit. Mean BCVA remained stable (p=0.95) (50.93±16.65 at baseline and 50.6±18.95 at final visit). The mean LCVA and RS showed insignificant improvement (p=0.31 and p=0.28, respectively).

Our pilot study demonstrated an improving trend in reduction of total HEX area and other anatomical outcomes, with limited functional outcomes. Larger randomized studies with a larger sample size with a control group are warranted to establish management protocols for DME with significant subfoveal HEX.