Retrospective analyses of optical coherence tomography in recurrent macular edema following intravitreal therapy in patients with retinal vein occlusion

BACKGROUND Optical coherence tomography has focused mainly on central subfield thickness to quantify macular edema in central and branch retinal vein occlusion. We examined macular fields other than the central subfield to determine if they are possibly independent indicators of recurrent macular edema. METHODS Single center, retrospective, consecutive case study of patients with recurrent macular edema secondary to either central or branch retinal vein occlusion. Thickness estimates of serial domain optical coherence tomography macular fields were obtained at the time of recurrent macular edema and analyzed retrospectively. Changes were expressed as a percentage of previous baseline levels. Change in thickness at each retreatment episode as well as average changes in thickness were calculated for each macular field for each eye. Data were analyzed via analysis of variance and Fisher's post hoc analyses. The macular field which most frequently had the largest percent increase at the time of recurrence was also assessed using averages for each subject as well as for each retreatment episode. Individual episodes of recurrent macular edema were also examined to ascertain the frequency in which there was minimal foveal edema (<15 μm increase), but non-foveal edema was considered severe enough to warrant retreatment. RESULTS 429 episodes of recurrent macular edema in 80 eyes were examined. In addition to the central subfield, the average mean change in thickness of the most affected quadrant (central vein occlusion) or hemisphere (branch vein occlusion) of the extrafoveal 3 mm band had the largest mean changes and also most frequently had the largest increases at the time of recurrent macular edema. In approximately 20 % of both central and branch occlusions, recurrent macular edema was detected in non-central macular fields in the absence of significant edema in the central subfield. CONCLUSIONS Analyses of non-central macular fields as well as the central subfield may be useful in the early detection and treatment of recurrent macular edema in retinal vein occlusion.