We applaud Lima de Carvalho and colleagues for their well-powered study entitled “Multimodal Imaging in Best Vitelliform Macular Dystrophy” (1).
In this paper, the authors performed a comprehensive multimodal imaging description of patients with Best vitelliform macular dystrophy. In detail, they employed quantitative fundus autofluorescence (qAF), near-infrared fundus autofluorescence (NIR-AF), and structural optical coherence tomography (OCT) to characterize affected eyes at different stages. This paper nicely demonstrated that a multimodal imaging approach may be useful to further characterize these patients and that each stage is featured by peculiar imaging characteristics.
Although we really enjoyed reading this paper, we have some concerns regarding the imaging descriptions proposed by the authors. In detail, 1 out of 28 eyes in their series was affected by the pre-vitelliform stage and, in this case, the authors asserted that OCT was not able to show any abnormalities. Since 2008, using structural OCT, Querques et al. (2-4) demonstrated that the pre-vitelliform stage is characterized by a thicker and more reflective appearance of the layer between a normal-appearing retinal pigment epithelium (RPE) and ellipsoid zone (EZ) interface. In the latter study, the authors speculated that this attribute may represent, at least in part, unphagocytized photoreceptor outer segments that accumulate above the RPE. In our opinion, this OCT feature is also evident in the pre-vitelliform eye enrolled in the study by Lima de Carvalho et al. (1), as it may be observed in Figure 1. In addition, the authors nicely identified a foveal hypofluorescence on the NIR-AF image from the pre-vitelliform stage eye. Assuming that NIR-AF is considered as a surrogate of melanin autofluorescence from the RPE and choroid, we speculate that this foveal hypofluorescence might be actually secondary to a “blocking effect” due to the presence of unphagocytized photoreceptor outer segments at the foveal level. We would claim that the authors did not appropriately identify this as a possible explanation to the early foveal hypofluorescence on NIR-AF. In addition, this “blocking effect” could also, at least in part, account for the foveal hypofluorescence identified in the other stages of the disease.
Furthermore, the authors concluded that the vitelliform lesion is composed of outer segment debris which accumulate because of separation of photoreceptor cells from the RPE, rather than an intrinsic defect of the RPE to phagocytose this material. This separation may be ascribable to the accumulation of fluid secondary to an impaired fluid transport (5). Although we agree that the exact mechanisms leading to the accumulation of vitelliform material in Best vitelliform macular dystrophy are still matter of debate, we would argue that the pre-vitelliform stage is characterized by an accumulation of material over the RPE, rather than a collection of subretinal fluid. The latter aspect highlights the point that we still need imaging evidence of this theory.
In conclusion, we certainly recognize the high value of the data reported in this paper. However, we believe that the authors failed to appropriately comment on an important OCT feature characterizing the pre-vitelliform stage, as well as they did not highlight that—at least with an imaging approach—there is no evidence that the accumulation of subretinal fluid might be the first pathogenic step in eyes affected by Best vitelliform macular dystrophy. We believe that these aspects of this study deserve a further explanation and therefore the authors’ feedback in this regard would be greatly appreciated.
