We read with interest the article “Unilateral BEST1-Associated Retinopathy” by Arora and associates. The authors described a series of 5 genetically proven Best vitelliform macular dystrophy (VMD) cases with unilateral clinical manifestations. The article is indeed interesting, and the images are straightforward; however, there are certain clinical details we wish to highlight.
Best VMD is an early-onset autosomal-dominant dystrophy characterized by accumulation of subretinal yellowish deposits of lipofuscin at the posterior pole. On the basis of opthalmologic examination, 5 different stages have been described: previtelliform (normal macula or subtle alteration of the retinal pigment epithelium [RPE]), vitelliform (well-circumscribed lesion resembling egg yolk), pseudohypopyon (yellow material accumulating inferiorly), vitelliruptive (the material undergoing partial resorbtion), and atrophic or fibrotic stage. The retinal changes are relatively symmetrical, even if some patients may feature asymmetrical manifestations.
Spectral-domain optical coherence tomography (SDOCT) allows in vivo visualization of intraretinal structures, especially the RPE and the inner segment (IS)/outer segment (OS) interface of the photoreceptors, also known also known as inner segment ellipsoid portion–ellipsoid zone (EZ) ; pathologic involvement of these structures has been described even in the early stages of Best VMD. In fact, the previtelliform stage is characterized by a hyperreflective thickening between a normal-appearing RPE and the IS/OS interface, preceding the classic deposition of vitelliform material.
After a careful analysis of the figures presented in the article by Arora and associates, we realized that all cases, except Case 1, feature this peculiar thickening at the IS/OS interface on SDOCT scan. Therefore, fellow eyes of Cases 2-5 might be classified as previtelliform phenotypes, rather than normal. The evidences of a high visual acuity and reduced electrooculogram light rise in these eyes are consistent with the early stage of the disease.
We would suggest these patients should be clinically reconsidered as bilaterally affected by Best VMD, and thus closely followed up to look for possible occurrence of more advanced manifestations of the disease. In addition, we would like to underline how SDOCT contributes to the diagnosis of Best VMD, especially at previtelliform stage, when the ophthalmoscopic pathognomonic signs of the disease are missing.