A macular dystrophy?

A 39-year-old male with known diabetes mellitus (DM) for 3 years and progressive diminution of vision in both eyes was referred to inherited retinal disease clinic with diagnosis of bull's eye maculopathy in both eyes. The best corrected visual acuity was 6/24 and 6/12 in the right eye and left eye, respectively. Anterior segments were normal in both eyes. Dilated fundus examination revealed ring-shaped perifoveal lesions in both eyes and pigmentary changes at the fovea [Fig. 1a and b]. Optical coherence tomography (OCT) showed subtle ellipsoid zone (EZ) attenuation, widening of foveal pit, and foveal thinning in both eyes [Fig. 2a and b].Figure 1: Fundus picture of (a) right eye and (b) left eye depicting ring shaped perifoveal lesions and pigmentary changes at foveaFigure 2: Optical coherence tomography of macula of (a) right eye and (b) left eye showing subtle ellipsoid zone attenuation, widening of the foveal pit and foveal thinningWhat would be your next step? – Full-field Electroretinogram (ERG) Indocyanine green angiography Fundus autofluorescence Fluorescein angiography Illustrations– Fig. 1a and b; Fig. 2a and b; Fig. 3a and b Figure 3: Fundus fluorescein angiography of (a) right eye and (b) left eye showing perifoveal leakage more in temporal side at macula and retinal telangiectasia Findings –Though the appearance was typical of bull's eye maculopathy or "Target sign," history of DM, relatively late presentation, and EZ attenuation in both eyes were not typical of bull's eye maculopathy. OCT of both eyes revealed temporal edges (right eye – 174 µm and left eye – 158 µm) of the fovea to be thinner than the nasal edges (right eye – 187 µm and left eye – 171 µm). Fundus fluorescein angiography (FFA) revealed perifoveal leakage more in the temporal macula and retinal telangiectasia [Fig. 3a and b]. There was no evidence of retinal/choroidal neovascularization. Diagnosis – Macular telangiectasia Type II (MacTel type 2) Correct answer – C) FFA has been the gold standard to confirm the diagnosis of MacTel type 2. Hallmark finding has been the characteristic telangiectatic capillaries on Fluorescein Angiography (FA), starting predominantly temporal to the fovea. Eventually, the entire parafoveal area is involved. Stereoscopic angiography has shown that the deeper vasculature is involved, but more superficial capillaries may also contribute to fluorescein leakage.[1] Although MacTel type 2 is common in females with DM after the age of 40, the typical clinical appearance aided by FFA helped to arrive at a diagnosis in this case. Discussion – MacTel Type 2 is usually bilateral and is commoner in DM. The earliest fundoscopic manifestation is a subtle loss of retinal transparency in the perifoveal region.[2] Development of neovascularization might be preceded by the right-angle venule and intraretinal pigment hyperplasia that is often temporal to the fovea.[1,2] Impaired reading vision, metamorphopsia, and mild visual impairments may be the presenting symptoms. In OCT, the earliest change may be temporal enlargement of the foveal pit, resulting in an asymmetric pit with the temporal area being thinner than the nasal area.[3] Other common OCT findings include Internal Limiting Membrane (ILM) drape and loss of retinal tissue.[3] Differential diagnosis includes branch retinal vein occlusion, diabetic retinopathy, and radiation retinopathy. In cases of neovascularization, Age Related Macular Degeneration (ARMD) should also be ruled out. There are no generally accepted therapies for this disease, especially when not associated with neovascularization. Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed. Financial support and sponsorship: Nil. Conflicts of interest: There are no conflicts of interest.