An anomalous course

CLINICAL SCENARIO A 72-year-old female presented with defective vision in her right eye (RE). On examination, her Snellen best corrected visual acuity was counting fingers at 1 meter in the RE and 6/6 in the left eye (LE). The anterior segment of both eyes was within normal limits, and pupils were bilaterally brisk. Her RE fundus [Figure 1] showed an elevation of the deep retina with associated hard exudates, and the optical coherence tomography (OCT) of the same showed a large dome-shaped detachment of retinal pigment epithelium with subretinal fluid [Figure 2]. Fluorescein angiography (FA) and indocyanine green angiography (ICGA) of the RE [Figure 3] showed multiple hyperfluorescent spots along the choroidal vessels, which were suggestive of polypoidal choroidal vasculopathy (PCV). Her LE fundus is shown in Figure 4.Figure 1: Right eyeFigure 2: Optical coherence tomography of the right eyeFigure 3: Fluorescein angiography and indocyanine green angiography of the right eyeFigure 4: Left eye fundusQuestion: What abnormality do you observe in the fundus of her LE? Answer: Congenital retinal macrovessel (CRM). DISCUSSION CRM is an aberrant retinal vessel that crosses the macula and supplies or drains the macula superior and inferior to the horizontal raphe.[1] These vessels originate from the mesenchyme at about the 15th to 16th week of gestation, when differentiation of retinal vessels into arteries and veins occurs.[2] It was first described by Mauthner in 1869, and the reported prevalence is 1 in 200,000.[2] It originates commonly from veins but occasionally may arise from arteries or from both arteries and veins.[3] Unlike normal macular vessels, these vessels are of a larger caliber and course across the horizontal raphe. Patients are usually asymptomatic with normal vision, and the disease is usually unilateral. A decrease in visual acuity in the eye affected by CRM could be due to a multitude of causes, such as CRM crossing the foveola, thickening, and distortion of the macular architecture due to CRM, foveal cyst, foveal ectopia, macular exudates, or hemorrhage, serous macular detachment, and due to a relative angioscotoma.[4] CRM is also known to be associated with cerebral venous malformations.[5] The patient in the given clinical scenario had an incidentally detected CRM in the LE. OCT of the LE [Figure 5] shows a normal fovea, but multiple areas of vascular shadowing due to the CRM coursing through the superficial layers of the retina can be observed. Her LE OCT angiography [Figure 6], FA, and ICG [Figure 7] clearly demonstrate the coursing CRM, which is seen to originate from the inferotemporal vein and travel toward the fovea. Another peculiarity is that she has multiple other CRM that do not course toward the fovea but instead form a communication between the superotemporal and inferotemporal vascular arcade in the LE.Figure 5: Optical coherence tomography of the left eyeFigure 6: Optical coherence tomography-A of the left eyeFigure 7: Fluorescein angiography and indocyanine green angiography of the left eyeFinancial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.