Torpedo Maculopathy: From Retinal Changes to Clinical Management

Torpedo maculopathy is a rare congenital retinal condition characterized by distinct alterations in the macula. Though typically asymptomatic, some individuals experience visual disturbances, making early recognition important for monitoring and management. The exact cause remains uncertain, but advancements in imaging have provided valuable insights into its structural characteristics.

Understanding torpedo maculopathy requires examining its retinal features, potential impact on vision, and available diagnostic tools. Exploring possible underlying mechanisms and associations with other ocular conditions can help refine clinical approaches.

Observed Retinal Features

Torpedo maculopathy presents as a well-defined, hypopigmented lesion in the temporal macula, typically oriented horizontally with a pointed nasal end and a broader temporal base. This distinct shape, resembling a torpedo, remains stable over time in most cases. The lesion is often located just inferior to the fovea, an area critical for central vision, yet rarely causes significant visual impairment. Fundoscopic examination reveals a depigmented appearance with variable degrees of retinal pigment epithelium (RPE) atrophy, sometimes accompanied by subtle hyperpigmented borders, suggesting localized alterations in melanin distribution.

Beyond surface pigmentation, optical coherence tomography (OCT) studies have demonstrated thinning of the outer retinal layers, particularly affecting the ellipsoid zone and RPE. In some cases, a cavitation-like defect indicates localized tissue loss. The choroid beneath the lesion may also appear slightly thinner, reinforcing the hypothesis of a developmental anomaly rather than an acquired degenerative process. Autofluorescence imaging highlights these abnormalities, often revealing hypoautofluorescence corresponding to areas of RPE loss, while some cases exhibit a hyperautofluorescent rim, possibly due to lipofuscin accumulation at the lesion’s periphery.

Despite its characteristic appearance, torpedo maculopathy varies in presentation. Some lesions display a more pronounced excavation, resembling a pseudocoloboma, while others maintain a relatively flat profile with minimal disruption to adjacent retinal structures. Longitudinal studies suggest the lesion remains largely stable, though subtle progressive changes in outer retinal integrity can occur, particularly in cases with extensive RPE involvement. Detailed imaging helps document structural variations and monitor for potential changes over time.

Visual Manifestations

Visual symptoms vary widely, with many individuals remaining asymptomatic while others report mild disturbances. When present, these disturbances often manifest as localized scotomas, particularly if the lesion encroaches upon the foveal or parafoveal region. Patients may describe a small, stationary blind spot or a subtle reduction in contrast sensitivity, which may become more noticeable in low-light conditions or during tasks requiring fine detail discrimination. Despite these potential deficits, most cases do not exhibit significant visual acuity loss, as the lesion typically spares the central fovea, preserving high-resolution vision.

Functional testing has provided insights into specific visual deficits. Microperimetry studies demonstrate reduced retinal sensitivity over the lesion site, aligning with structural alterations observed on imaging, particularly where the ellipsoid zone is disrupted. Multifocal electroretinography (mfERG) findings further support this correlation, revealing decreased amplitudes in the affected retinal region while maintaining normal responses elsewhere. These electrophysiological changes suggest compromised photoreceptor integrity within the lesion, contributing to visual field defects.

Some patients experience subtle metamorphopsia, particularly if the lesion alters the underlying retinal architecture. This distortion is more pronounced in cases with cavitary changes, leading to irregularities in photoreceptor alignment. Amsler grid testing can sometimes reveal minor distortions, though findings are typically less pronounced compared to conditions like macular edema or epiretinal membranes. Given the generally stable nature of the lesion, any progressive visual changes warrant further evaluation to rule out secondary complications such as choroidal neovascularization, which has been reported in rare instances.

Cross-Sectional Imaging Methods

Advancements in retinal imaging have significantly improved the characterization of torpedo maculopathy. Optical coherence tomography (OCT) serves as a primary tool for assessing the lesion’s depth and extent, revealing disruptions in outer retinal layers, particularly within the ellipsoid zone and RPE. High-resolution spectral-domain OCT (SD-OCT) provides cross-sectional visualization of these abnormalities, frequently demonstrating a concave or cavitary defect. In some cases, the attenuation of underlying choroidal tissue supports the hypothesis that torpedo maculopathy arises from a congenital developmental anomaly rather than a progressive degenerative process.

Fundus autofluorescence (FAF) enhances the evaluation of RPE integrity by detecting variations in lipofuscin distribution. Hypoautofluorescence is commonly observed in the central portion of the lesion, corresponding to areas of RPE atrophy, while a hyperautofluorescent rim may indicate focal metabolic stress or compensatory changes. This contrast in autofluorescence patterns provides further insight into lesion stability, as progressive enlargement of hypoautofluorescent areas may suggest subtle deterioration in RPE function. FAF imaging plays a key role in longitudinal monitoring.

Optical coherence tomography angiography (OCTA) has provided additional insights into the vascular characteristics of torpedo maculopathy. While conventional fluorescein angiography (FA) typically shows no leakage, OCTA has occasionally demonstrated reduced choriocapillaris flow beneath the lesion. This vascular alteration, though not universally present, suggests a localized disturbance in choroidal circulation. The absence of neovascularization in most cases differentiates torpedo maculopathy from other macular pathologies that share similar outer retinal disruptions, such as choroidal neovascular membranes or central serous chorioretinopathy.

Theoretical Pathophysiology

The underlying mechanisms driving torpedo maculopathy remain uncertain, but prevailing theories suggest a developmental anomaly affecting the retinal pigment epithelium (RPE) and its interaction with the choroid. One hypothesis proposes that the lesion results from incomplete differentiation or migration of RPE cells during fetal development. Given its consistent localization in the temporal macula, this theory aligns with the idea that a disruption in regional signaling pathways could lead to a failure in proper RPE organization. Some cases exhibit subtle thinning in the choroid, suggesting vascular irregularities during embryogenesis might contribute to the condition’s formation.

Another perspective considers a defect in the fetal temporal bulge, a transient embryonic structure that influences macular development. This structure guides the maturation of surrounding retinal tissues, and any disruption in its regression could leave behind an area of structural deficiency. The characteristic torpedo-like shape may reflect the directional influence of this developmental process, with the pointed end representing an area of incomplete closure or migration. While postnatal changes in the RPE and photoreceptors may further shape the lesion’s appearance, its congenital nature suggests the primary defect originates early in retinal formation.

Associations With Other Eye Conditions

Torpedo maculopathy is generally considered an isolated congenital anomaly, but occasional reports suggest coexistence with other ocular conditions. Some studies have documented mild refractive errors, particularly myopia, in individuals with torpedo maculopathy. While this association does not imply causation, it raises questions about whether subtle developmental variations in retinal and choroidal structures contribute to both findings.

Rare reports link torpedo maculopathy with choroidal neovascularization (CNV). While most cases remain stable, isolated instances of CNV development suggest localized RPE atrophy and choroidal thinning could, in some cases, create an environment conducive to abnormal vascular proliferation. CNV significantly alters the clinical course, potentially leading to progressive visual decline if left untreated. Long-term monitoring with multimodal imaging is advised in patients showing structural progression or new visual symptoms. Early detection of secondary complications allows for timely intervention, preserving visual function.

Clinical Management Approaches

Since torpedo maculopathy is typically asymptomatic and non-progressive, management primarily focuses on observation rather than active treatment. Routine ophthalmologic examinations with fundus photography and OCT are recommended to document baseline characteristics and monitor for structural changes. In cases with visual disturbances, functional assessments such as microperimetry help quantify localized deficits and guide patient counseling. Significant changes over time are uncommon, but periodic follow-up ensures any unexpected alterations are promptly identified.

For individuals who develop complications such as choroidal neovascularization, intervention becomes necessary. Anti-vascular endothelial growth factor (anti-VEGF) therapy, commonly used for CNV in conditions like age-related macular degeneration, has been effective in rare instances of neovascularization in torpedo maculopathy. While these cases are exceptional, awareness of potential secondary changes is important in determining when escalation of care is required. Patients experiencing new visual symptoms, particularly metamorphopsia or a sudden decline in acuity, should undergo immediate imaging to assess for CNV formation.