Objective: To describe a standardized method for reporting quantitative changes in macular thickening using optical coherence tomography (OCT).
Methods: The proposed method consists of calculating the actual change in central foveal thickening (the initial pretreatment thickness minus the posttreatment thickness) using OCT and dividing that value by the potential change (the initial pretreatment thickness minus the normal thickness based on normative data) to provide the total improvement in macular edema as a percentage. We refer to this method as the standardized change in macular thickening (SCMT). To illustrate the effectiveness of this method, we performed a retrospective review of 2 studies that evaluated different strategies for treating refractory macular edema.
Results: Patients treated with intravitreal triamcinolone acetonide for refractory diabetic macular edema had an overall SCMT of approximately 75%, 78%, and 55% at the 1-, 3-, and 6-month follow-up visits, respectively. More than half of the patients in the study cohort (9 of 16 patients) experienced greater than 80% SCMT at the last follow-up visit. Patients who underwent vitrectomy for a taut, thickened posterior hyaloid on OCT responded with an SCMT of approximately 78% at the 3-month follow-up visit and 87% at the final follow-up visit (mean, 19 months). Patients who underwent vitrectomy for diabetic macular edema unresponsive to laser photocoagulation but with no evidence of vitreomacular traction experienced an SCMT of 37% at the 3-month follow-up visit and 20% at the final follow-up visit (mean, 17 months).
Conclusion: The proposed method offers an objective and intuitive basis for evaluating and comparing the efficacy of different therapeutic modalities.