[Hypopigmentation temporal to the macula. Case report: torpedo maculopathy]

Multimodal Imaging of Torpedo Maculopathy With Fluorescence Adaptive Optics Imaging of Individual Retinal Pigmented Epithelial Cells

Torpedo maculopathy (TM) is a rare congenital defect of the retinal pigment epithelium (RPE). The RPE is often evaluated clinically using fundus autofluorescence (AF), a technique that visualizes RPE structure at the tissue level from the intrinsic AF of RPE fluorophores. TM lesions typically emit little or no AF, but this macroscopic assessment is unable to resolve the RPE cells, leaving the organization of the RPE cell mosaic in TM unknown. We used fluorescence adaptive optics scanning laser ophthalmoscopy (AOSLO) to show here for the first time the microscopic cellular-level structural alterations to the RPE cell mosaic in TM that underlie the tissue-level changes seen in conventional clinical imaging. We evaluated two patients with TM using conventional clinical imaging techniques and adaptive optics (AO) infrared autofluorescence (IRAF) in AOSLO. Confocal AOSLO revealed relatively normal cones outside the TM lesion but altered cone appearance within it and along its margins in both patients. We quantified cone topography and RPE cell morphometry from the fovea to the margin of the lesion in case 1 and found cone density to be within the normal range across the locations imaged. However, RPE morphometric analysis revealed disrupted RPE cells outside the margin of the lesion; the mean RPE cell area was greater than two standard deviations above the normative range up to approximately 1.5 mm from the lesion margin. Similar morphometric changes were seen to individual RPE cells in case 2. Multi-modal imaging with AOSLO reveals that RPE cells are abnormal in TM well beyond the margins of the characteristic TM lesion boundary defined with conventional clinical imaging. Since the TM fovea appears to be fully formed, with normal cone packing, it is possible that the congenital RPE defect in TM occurs relatively late in retinal development. This work demonstrates how cellular level imaging of the RPE can provide new insight into RPE pathologies, particularly for rare conditions such as TM.

Choroidal Cavitary Disorders

The structure and functions of the choroid have been long acknowledged but the pathophysiology behind various anomalies has been difficult to understand until the advent of optical coherence tomography (OCT). With OCT imaging, choroidal cavitations appear as optically empty spaces between the outer retinal and choroidal layers with attenuation or loss of outer retinal layers. Choroidal cavitations are found in the posterior pole and seen in conditions such as pathologic myopia, north carolina macular dystrophy (NCMD), focal choroidal excavation (FCE), and torpedo maculopathy (TM). To date, these disorders have not been linked. A commonality they all share is malformation of the RPE-photoreceptor-choroid complex. The following report describes the differences and similarities of choroidal cavitation amongst the different retinal disorders and emphasizes the importance of multimodal imaging in the detection and management of potential complications.

Distribution patterns of torpedo maculopathy: Further evidence of a congenital retinal nerve fiber layer-driven etiology

With fewer than 100 peer-reviewed cases reported in the world to date, the underlying etiology of torpedo maculopathy has remained elusive. In this literature review, we provide new evidence to better support, reject and unify claims regarding cause, diagnosis, and proper clinical management of this disease. We reviewed 44 case reports and case series, which included 77 patients (after exclusions). We additionally introduced 3 new cases from our clinical practice for a total of 80 cases. Ages at presentation ranged from 6 months old to 73 years old (mean: 24.2 years old). The nasal aspects of torpedo maculopathy lesions pointed toward the optic disc and localized to a kite-shaped region of the temporal macula, correlating with the anatomic junction of the superior arcuate, inferior arcuate, and papillomacular bundles of retinal nerve fiber layer distribution. No patterns were observed among the temporal aspects of the lesions. These findings support a congenital etiology of torpedo maculopathy and a possible influence of the retinal nerve fiber layer in the development of mature retinal pigment epithelium.