What is now referred to as torpedo maculopathy was initially described as a hypopigmented nevus of the macula.1 It has more recently been described as an asymptomatic torpedo-shaped defect in the retinal pigment epithelium (RPE) with its tapered end characteristically directed toward the fovea.2 The underlying etiology is unclear, but possible mechanisms include a defect in RPE development in the fetal macular bulge3 and a malformation of the emissary canal of the long posterior ciliary neurovascular bundle.2 The lesion is occasionally associated with a visual field defect and all published data suggest that the lesion is non-progressive. Recent studies have described optical coherence tomography (OCT), fundus autofluorescence, microperimetry, and visual field findings in patients with torpedo maculopathy.2,4–6 In this study, we describe the OCT and fundus autofluorescence findings in a patient with torpedo maculopathy and compare it to previously published data.
An 8-year-old girl was referred by her primary care physician in November 2013 after failing vision screening in her right eye. Her best-corrected visual acuities were 20/20 in both eyes following correction of 1 diopter of myopia in each eye. Anterior segment examination was unremarkable in both eyes. Posterior segment examination of the right eye was unremarkable. Posterior segment examination of the left eye revealed a hypopigmented ovoid lesion of the temporal macula with a tapered end pointing toward the center of the macula (Figure 1A). The temporal edge was pigmented and there was a smaller satellite lesion just temporal to the primary lesion. Fundus autofluorescence (HRA 2; Heidelberg Engineering, Dossenheim, Germany) showed decreased fundus autofluorescence of the lesion with the margin showing stippled increased fundus autofluorescence (Figure 1C). High-resolution spectral-domain OCT (Spectralis OCT; Heidelberg Engineering, Heidelberg, Germany) with a line scan (Figure 1B) through an area of increased fundus autofluorescence revealed an intact RPE with loss of the interdigitation zone (Figure 1D). A line scan through the center of the fovea revealed normal inner retinal architecture but thickening of the interdigitation zone with possible detachment of the photoreceptor tips from the RPE and upward displacement of the ellipsoid zone just temporal of the fovea, as well as sub-RPE cleft formation (Figure 1E). More temporally, there was loss of both the ellipsoid and interdigitation zones, as well as RPE atrophy as evidenced by increased transitivity to the choroid (Figure 1F). The outer nuclear layer appeared thinner above the zones of RPE atrophy, but it was difficult to measure due to the change in reflectivity of Henle’s layer.
Torpedo maculopathy. (A) Color fundus photograph showing a classic “torpedo” lesion with a smaller satellite lesion temporal to this. (B) Infrared image with line scans through areas of interest. (C) Fundus autofluorescence (FAF) image. The dotted lines show the corresponding location to the line scans in the infrared image. FAF reveals reduced autofluorescence of the lesion and a rim of increased autofluorescence along the margin of the lesion. The top dotted line passes through an area of increased FAF (arrow). (D–F) Horizontal spectral-domain optical coherence tomography images corresponding to the line scans in (B, C). (D) Photoreceptor loss with intact retinal pigment epithelium (RPE) (arrows) corresponding to an area of increased FAF. (E) Thickening of the interdigitation zone (arrow) and sub-RPE cleft formation (arrowhead). (F) Loss of the ellipsoid zone, interdigitation zone and RPE atrophy with increased transitivity to the choroid.
Torpedo maculopathy remains a rare and poorly understood condition. The non-random location of the torpedo lesion points to a congenital etiology. Our OCT findings support a congenital defect in the RPE with degeneration of the overlying outer neurosensory retina. In the past decade, there have been a few publications describing OCT findings in torpedo maculopathy. The findings are not homogeneous. Golchet et al.2 described lesions as having a normal inner retina, slightly thinned outer retina overlying a cleft, and a thinned RPE with increased signal transmission similar to our findings. Others have described an atrophic inner and outer neurosensory retina.5,6 Additionally, RPE atrophy does not appear to be universal among all cases of torpedo maculopathy; one study noted normal RPE architecture.6
An interesting OCT finding in patients with torpedo maculopathy is the presence of a sub-RPE cleft. In the study by Golchet et al.,2 this cleft was associated with locally absent RPE. This cleft has been described by others as a neurosensory retinal detachment.5,7 In our patient, we observed thickening of the interdigitation zone and separation from underlying structures creating a cleft.
There was reduced fundus autofluorescence of the lesion and a ring of increased fundus autofluorescence along the margin of the lesion. The absence of fundus autofluorescence of the lesion indicates a dramatic reduction of fluorophores suggesting severe RPE dysfunction or absence. The margin of increased fundus autofluorescence noted in this patient has not been previously described in torpedo maculopathy. In other published cases of torpedo maculopathy in which fundus autofluorescence was performed, the lesion showed decreased fundus autofluorescence and the lesion appeared non-progressive on follow-up of these patients.2,4
Intense fundus autofluorescence can be noted around patches of geographic atrophy in age-related macular degeneration and is thought to be due to lipofuscin and melanolipofuscin accumulation in RPE cells of this junctional zone of atrophy.8 Studies have shown a clear association between the extent of increased fundus autofluorescence in this junctional zone of atrophy and the rate and extent of progression of geographic atrophy.8–10 It is therefore conceivable that torpedo maculopathy lesions displaying such a ring of increased fundus autofluorescence surrounding an area of RPE disturbance have the potential to progress. Alternatively, increased fundus autofluorescence can result from photoreceptor loss with preservation of the underlying RPE, as seen in Figure 1D, in essence creating a window effect. Such a configuration could also result in the pattern of increased fundus autofluorescence.
Although there are no histopathologic studies of lesions in torpedo maculopathy, multimodal imaging has given great insight into this condition. However, there does appear to be a heterogeneity of findings on various imaging modalities, including OCT and fundus autofluorescence. Novel findings in this study include the presence of increased fundus auto-fluorescence along the margin of the torpedo lesion and the presence of a smaller satellite lesion adjacent to the torpedo lesion.
- Roseman RL, Gass JD. Solitary hypopigmented nevus of the retinal pigment epithelium in the macula. Arch Ophthalmol. 1992;110:1358–1359. doi:10.1001/archopht.1992.01080220020005 [CrossRef]
- Golchet PR, Jampol LM, Mathura JR, Daily MJ. Torpedo maculopathy. Br J Ophthalmol. 2010;94:302–306. doi:10.1136/bjo.2009.162669 [CrossRef]
- Shields CL, Guzman JM, Shapiro MJ, Fogel LE, Shields JA. Torpedo maculopathy at the site of the fetal “bulge.”Arch Ophthalmol. 2010;128:499–501. doi:10.1001/archophthalmol.2010.29 [CrossRef]
- Pilotto E, Zannin ME, Convento E, Cortese M, Midena E. Torpedo maculopathy: a morphofunctional evaluation. Int Ophthalmol. 2013;33:71–74. doi:10.1007/s10792-012-9618-1 [CrossRef]
- Sanabria MR, Coco RM, Sanchidrian M. OCT findings in torpedo maculopathy. Retin Cases Brief Rep. 2008;2:109–111. doi:10.1097/ICB.0b013e318033a130 [CrossRef]
- Tsang T, Messner LV, Pilon A, Lombardi L. Torpedo maculopathy: in-vivo histology using optical coherence tomography. Optom Vis Sci. 2009;86:E1380–E1385. doi:10.1097/OPX.0b013e3181be0724 [CrossRef]
- Su Y, Gurwood AS. Neurosensory retinal detachment secondary to torpedo maculopathy. Optometry. 2010;81:405–407. doi:10.1016/j.optm.2010.06.001 [CrossRef]
- Schmitz-Valckenberg S, Fleckenstein M, Scholl HP, Holz FG. Fundus autofluorescence and progression of age-related macular degeneration. Surv Ophthalmol. 2009;54:96–117. doi:10.1016/j.survophthal.2008.10.004 [CrossRef]
- Holz FG, Bindewald-Wittich A, Fleckenstein M, et al. Progression of geographic atrophy and impact of fundus autofluorescence patterns in age-related macular degeneration. Am J Ophthalmol. 2007;143:463–472. doi:10.1016/j.ajo.2006.11.041 [CrossRef]
- Schmitz-Valckenberg S, Bindewald-Wittich A, Dolar-Szczasny J, et al. Correlation between the area of increased autofluorescence surrounding geographic atrophy and disease progression in patients with AMD. Invest Ophthalmol Vis Sci. 2006;47:2648–2654. doi:10.1167/iovs.05-0892 [CrossRef]