We thank Caimi and associates for their interest in our article regarding serous macular detachment in Waldenström macroglobulinemia. They describe 1 patient in whom cystoid macular edema and serous macular detachment was present without outer retinal disruption on spectral-domain optical coherence tomography. In our case series, 4 patients had bilateral cystoid macular edema overlying a serous retinal detachment. All 4 eyes of the 2 patients who underwent spectral-domain optical coherence tomography imaging demonstrated outer retinal defects overlying a serous macular detachment. We hypothesized that these defects could provide a pathway for immunoglobulin M molecules and intraretinal fluid to enter the subretinal space, thereby creating a serous macular detachment in the setting of a so-called silent fluorescein angiogram.

Although the patient of Caimi and associates may suggest that outer retinal defects are not responsible for serous retinal detachment in Waldenström macroglobulinemia, an alternative explanation is that the stability of the outer retina may fluctuate during the disease course. Because the breakdown of the external limiting membrane theoretically is caused by cystoid macular edema-related traction on Müller cells and photoreceptors, it is possible that improvement in cystoid macular edema leads to re-establishment of outer retinal integrity. The restoration of the external limiting membrane and photoreceptor outer segments over time has been well documented in other conditions such as repaired macular holes. If small outer retinal defects can close over time, it is possible that the patient reported by Caimi and associates was examined at a later stage in the disease process. Conversely, when outer retinal defects become too large or chronic, they remain open and lead to persistent subretinal fluid. This plasticity may be the reason that some patients with Waldenström macroglobulinemia have progressive serous retinal detachments, whereas others show stabilization or improvement over time.

We agree that the pathogenesis of serous macular detachment in Waldenström macroglobulinemia is not understood completely. Intraretinal fluid tracking through outer retinal defects is one hypothesis, but other mechanisms also may be involved. We look forward to further investigations from their group and others.