Comment on: "Multimodal imaging in dominant cystoid macular dystrophy".

Sir,

The author read with interest the article on multimodal imaging of dominant cystoid macular dystrophy (DCMD).[1] There are few challenges that need discussion.

Bilateral hyporeflective spaces in macular optical coherence tomography in a young male may also be noted in juvenile retinoschisis or X-linked retinoschisis (XLRS),[2] and peripheral retinoschisis may be absent in 50% of such cases. The fovea in magnified pictures of Fig. 1[1] does appear to have a spoke-wheel appearance which is typical of XLRS

In the present case, both the foveae showed such hypoechoic spaces separated by vertically oriented retinal tissue bridges, which may be noted in foveoschisis of XLRS. A close differential diagnosis of such finding is cystoid macular edema (CME). However, CME shows typical petaloid leak (contrary to foveoschisis[3]) in the late phase of fundus fluorescein angiography. The first description of DCMD noted “typical CME due to leaking perimacular capillaries. Other striking features were retinal capillary leakage all over the posterior pole of the eye, whitish punctate deposits in the vitreous body, a normal electroretinogram, a subnormal electro-oculogram, and moderate-to-high hyperopia.”[4] The petaloid leak is not clearly demonstrated in Fig. 6 of the publication[1]

In such a diagnostic dilemma, it would be interesting to know the fundus findings of the family members if they were examined. Reported patients of DCMD include Dutch family, American family with Greek ancestors, and patients from America and Spain.[5] All the 97 patients with DCMD in a large study had a single common Dutch ancestor. A pedigree chart with a search for an ancestor may be of help. The refractive error and axial length of the patient should be reported though both XLRS and DCMD can show hyperopia which may be more severe in DCMD. Electroretinogram shows a typical negative waveform with absent b wave in XLRS which unfortunately could not be performed as the patient refused such tests[1] as noted in the publication. Genetic analysis could also have helped in the exact diagnosis of the presented patient, which is difficult in Indian scenario due to the financial constraints

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