A deeper look at torpedo maculopathy

Transcription

1 CLINICAL AND EXPERIMENTAL REVIEW A deeper look at torpedo maculopathy Clin Exp Optom 2017; 100: Casey Hamm* OD Diana Shechtman OD FAAO Sherrol Reynolds OD FAAO *College of Optometry, University of Missouri-St. Louis, Saint Louis, Missouri, USA College of Optometry, Nova Southeastern University, Fort Lauderdale, Florida, USA hammcm@umsl.edu Submitted: 15 December 2016 Revised: 8 January 2017 Accepted for publication: 17 January 2017 DOI: /cxo Background: Torpedo maculopathy is a rare, congenital maculopathy classically diagnosed funduscopically as a torpedo-shaped lesion located temporal to the fovea. This case describes a torpedo maculopathy with non-classic optical coherence tomographic (OCT) findings and collaborative OCT angiographic (OCTA) findings. Case report: A 60-year-old Caucasian woman presented with a history of longstanding distortion and paracentral scotoma of the right eye. She had a positive family history of agerelated macular degeneration. Visual acuity was 6/6 in each eye. Dilated fundus examination revealed a torpedo-shaped lesion in the right eye with a hypo-pigmented head pointing toward the fovea and a hyper-pigmented tail end. OCT imaging of the macula of the right eye revealed a subretinal cleft space with underlying thinning of the retinal pigment epithelium, increased choroidal reflectivity, as well as retinal pigment epithelial and choroidal excavation. OCTA choriocapillaris segmentation showed a hyporeflective area associated with the lesion, adjacent to hyper-reflectivity. The patient was diagnosed with torpedo maculopathy of the right eye. Conclusions: OCT and OCTA imaging have been instrumental in developing a deeper understanding of many maculopathies, allowing for accurate diagnosis of macular conditions. Although the aetiology remains unclear, these imaging devices may provide further insight into the lesion in torpedo maculopathy. Key words: OCTA, optical coherence tomography, torpedo maculopathy Torpedo maculopathy is a rare, congenital anomaly of the retinal pigment epithelium (RPE) characterised by the appearance of a torpedo-shaped lesion located temporal to the fovea. It was first described by Roseman and Gass in 1992 as an asymptomatic hypo-pigmented naevus of the retinal pigment epithelium. 1 It has also been described as a paramacular coloboma, 2 albinotic naevus, amelanotic spot, congenital hypo-melanotic freckle and subsequently, torpedo maculopathy. 3 A diagnosis of torpedo maculopathy is typically made on the basis of funduscopic appearance of the lesion. Classic finding is a solitary hypo-pigmented lesion that is oval in shape, resembling a bullet or torpedo, with a wedge-shaped tail extending outward and pointing toward the foveola along the horizontal raphe. 4 This characteristic presentation is pathognomonic for torpedo maculopathy and helps to distinguish it from other lesions, such as congenital hypertrophy of the RPE (CHRPE) and chorioretinal scar. Although the cause of torpedo maculopathy is unknown, optical coherence tomography (OCT) has provided insight into the structural and possible pathophysiologic changes associated with the lesion. 5,6 The OCT findings vary and may represent different stages of the condition. OCT images of eyes with torpedo maculopathy reveal an outer retinal and subretinal pigment epithelial cleft with associated retinal pigment epithelial thinning that may be attributed to several developmental defects including a malformation of the horizontal raphe nerve fibres 2 and a failure of the foetal temporal bulge to progress into the adult macula. 7 Other pathologic causes like congenital outpouching of the choroid, 4 degenerative choroidal thinning and consequent separation of the photoreceptors from the RPE, have also been observed with OCT evaluation. 5 Optical coherence tomographic angiography (OCTA), a non-invasive visualisation of the retinal and choroidal vasculature, may provide further understanding of the pathological process of this disorder. A case of torpedo maculopathy with distinct OCT and OCTA findings is presented. CASE REPORT A 60-year-old Caucasian woman presented with a complaint of mild distortion and paracentral scotoma of the right eye that was longstanding. Previous practitioners told her she had a chorioretinal scar in the macula that was the source of her symptoms. She was monitoring the visual disturbance with home Amsler grid testing. Systemic conditions included hypertension and prior infection with pneumonia and a variant of the H1N1 virus (influenza V virus), both of which were treated and had completely resolved. She was taking a multivitamin, biotin, fish oil, calcium, vitamin C supplements and anti-hypertensive medications. She had a positive family ocular history of age-related macular degeneration. Ocular examination revealed a visual acuity of 6/6 in the right and left eyes. Pupils were equal, round and reactive to light with no afferent pupillary defect. Ocular motilities and confrontation visual fields were unremarkable in both eyes Optometry Australia Clinical and Experimental Optometry November

2 Due to her Amsler grid defect in the right eye, a Humphrey 10-2 SITA Standard visual field was performed. This revealed a four-point defect (p < 0.01) in the superior nasal field of the right eye (Figure 1), corresponding to the area of reported distortion on the Amsler grid. Visual field testing for the left eye was unremarkable (Figure 2). Dilated fundus examination revealed flat, sharp and pink optic nerves with normal physiologic cupping in each eye. Examination of the macula in the right eye revealed a torpedo-shaped, hypopigmented chorioretinal lesion with a parafoveal point and a hyper-pigmented tail extending temporally (Figure 3). The macula of the left eye was unremarkable with normal pigmentation (Figure 4). The peripheral fundus was flat and intact in both eyes with no holes, tears or detachments. Spectral-domain OCT imaging with Cirrus HD-OCT (Carl Zeiss Meditec, Dublin, California, USA) revealed an area of mild retinal thinning in the temporal parafovea, with normal central foveal thickness in the right eye (Figure 5). A discrete area of subfoveal excavation of both the choroid and RPE was also observed, forming a subretinal cleft with underlying retinal pigment epithelial thinning and increased choroidal reflectivity (Figure 5). Other noted OCT findings included a subretinal hypo-reflective space separating the RPE from the overlying retina, significant atrophy of the outer retinal structures, a disrupted ellipsoid zone, thinned outer plexiform layer and an almost absent outer nuclear layer. Vitreopapillary traction was also observed in the right eye. OCT imaging of the left eye was unremarkable with normal foveal contour (Figure 6). OCTA choriocapillaris vasculature segmentation showed a hypo-reflective area corresponding to the hyper-pigmented end of the lesion. An adjacent increased signal reflectivity associated with increased density of the choroidal vasculature was also noted, corresponding to the Figure 1. Central 10-2 SITA Standard visual field of the right eye. Four-point defect in the superior nasal field, corresponding to the area of reported distortion on an Amsler grid and to the location of the torpedo lesion in the temporal macula. Clinical and Experimental Optometry November Optometry Australia

3 parafoveal point (Figure 7). Correlating en face OCTA of the right macula showed decreased reflectivity, in addition to an adjacent area of increased reflectivity corresponding to the parafoveal point (Figure 8). OCTA choriocapillaris vasculature segmentation of the contralateral eye showed a normal, dense homogenous image (Figure 9). Based on the clinical findings, the patient was diagnosed with torpedo maculopathy in her right eye. She is being monitored with home Amsler grid testing and close follow-up evaluation every three to six months. DISCUSSION Figure 2. Central 10-2 SITA Standard visual field of the left eye was unremarkable Torpedo maculopathy is a rare maculopathy that is often asymptomatic and typically found during routine examination. The condition is commonly unilateral, although bilateral cases have been reported. 8,9 Torpedo maculopathy has a hallmark clinical appearance of an oval ( torpedo-like ), hypo-pigmented, flat retinal pigment epithelial lesion with distinct borders located in the temporal macula. The typical size of the lesion is two disc diameters horizontally by one disc diameter vertically, 4 usually without foveal involvement. 4,10 The hypopigmented head points toward the fovea with a rounded tail facing away. 4 The tail of the lesion varies in appearance, often presenting with a hyper-pigmented, welldemarcated or frayed edge. 4 Despite the classic appearance, the rarity and unknown cause of this disorder may pose a diagnostic challenge. Differential diagnosis of torpedo maculopathy includes CHRPE, simple hamartoma of the RPE 4 and congenital toxoplasmosis, as well as other chorioretinal scars. Figure 3. Fundus photograph of the right eye. A hypo-pigmented, torpedo-shaped lesion is observed in the macula. There is a parafoveal point and a hyper-pigmented, rounded tail extending temporally. Figure 4. Fundus photograph of the left eye shows a normal macula with torpedo lesion absent Visual function Because the central fovea is not involved in most torpedo lesions, visual acuity is generally unaffected. 3,10 In rare instances, vision can be reduced, particularly if the lesion is impinging on the fovea, 4 but this is more likely when ocular co-morbidities are present. Visual function may also be compromised by visual field loss, 4 usually in the form of a central scotoma observed on standard automated perimetric testing. 1 Microperimetry may demonstrate reduced macular sensitivity with dense 2017 Optometry Australia Clinical and Experimental Optometry November

4 Figure 5. Spectral-domain five-line raster optical coherence tomographic (OCT) scan of the right macula, imaged with Cirrus HD-OCT. A discrete excavation of both the choroid and retinal pigment epithelium (RPE) is observed, forming a subretinal cleft with underlying RPE thinning and increased choroidal reflectivity. The outer retinal structures are significantly atrophied, with a ragged ellipsoid zone, an almost absent outer nuclear layer and a thinned outer plexiform layer. Inner retinal structures are unaffected. microscotoma corresponding to the lesion s location. 4 Fundus autofluorescence The torpedo-shaped lesion exhibits an associated hypo-fluorescence with fundus autofluorescence imaging. Focal choroidal excavation as detected by OCT has been found to exhibit various corresponding pigmentary changes with auto-fluorescence depending on the amount of retinal pigment epithelial involvement. 6 Torpedo maculopathy specifically exhibits a border of hyper-fluorescence along the margin of the hypo-fluorescent lesion. 6 Decreased fundus auto-fluorescence represents atrophic RPE ( dead RPE), while a hyperfluorescence represents the build-up of lipofuscin within dysfunctional retinal pigment epithelial cells or those under metabolic stress ( dying RPE). Therefore, the general finding of hypo-fluorescence supports the finding of atrophied or missing RPE within lesions, to some extent. Optical coherence tomography and OCT angiography Optical coherence tomography findings in torpedo maculopathy include retinal pigment epithelial thinning and photoreceptor loss with retinal pigment epithelial and choroidal hypereflectivity. 5,10 A classic sign of torpedo maculopathy involves a shallow subretinal cleft, as seen in our case, generally with an underlying non-excavated RPE and choroid. This cleft is thought to be created by a loss of RPE and photoreceptors within the lesion. 4,6 In addition, the overlying neurosensory retina may be thinned and/or disrupted. 10 More recently, detailed evaluation through spectral-domain OCT analysis has expanded the spectrum of the disease to include excavation involving the choroid, like that described in focal choroidal excavation and as seen in our case. 4 Other findings have included a subretinal cleft with thinning of the overlying outer retina, in addition to increased signal transmission. 5 Wong and colleagues 11 classified OCT appearances associated with torpedo maculopathy as Type I, which involves attenuation of the outer retina in the absence of outer retinal cavitation, and Type II, which exhibits both outer retinal abnormalities as well as outer retinal excavation, but not necessarily choroidal involvement. OCTA is a non-invasive imaging device that uses the principles of decorrelation to detect red blood cell movement to map out the retinal and choroidal vascular system. Recently, the OCTA findings associated with torpedo lesions were described by Papastefanou and colleagues, 12 with OCTA choroidal vascular segmentation showing hypo-reflectivity (atrophy) correlating to the OCT subretinal cleft. Adjacent disruption was noted in the vicinity of the tail of the lesion, potentially correlating to a transmission defect. 12 These findings were consistent with the OCTA findings in our patient. Additionally, OCTA en face imaging has shown decreased flow associated with the OCT subretinal cleft, in addition to a surrounding hyper-reflectivity corresponding to the tail. This novel visualisation of the choroid may provide new insight on the pathogenesis of this disorder, as previous diagnostic modalities, such as fluorescein angiography, were incapable of enhancing visualisation of the choroidal vasculature. Aberrant choroidal circulation has been proposed as a possible mechanism to explain torpedo maculopathy and may become more apparent with age. 12 OCTA has provided a better understanding of alterations within the choroid, although more evaluation is necessary to help determine whether choroidal changes are the primary event or are associated with the progression of the condition. 12 In 2011, Margolis and colleagues 13 further expanded upon the spectrum of the condition, stating a case of focal choroidal excavation had a discrete area of pigmentary and fundus auto-fluorescent changes that resemble torpedo maculopathy, similar to our presented case. Thus historically, torpedo maculopathy affects the outer Clinical and Experimental Optometry November Optometry Australia

5 Figure 6. Spectral-domain five-line raster optical coherence tomographic (OCT) scan of the left macula, as imaged with Cirrus HD-OCT, was unremarkable and revealed normal foveal contour Figure 7. Optical coherence tomographic angiography (OCTA) choroidal vasculature segmentation of the right macula, imaged with Cirrus HD-OCT. The scan reveals a loss of vessels (hypo-reflective area) corresponding to the OCT subretinal cleft in the right eye. An adjacent increase in signal reflectivity associated with increased density of the choroidal vasculature is noted, correlating with the location of the torpedo tail. retina and RPE, with or without an underlying choroidal excavation. This collaborates the fact that torpedo maculopathy has been linked to variable OCT and OCTA findings, likely representing a spectrum of a pathological process. Management In general, torpedo maculopathic lesions have been found to remain stable with no risk of vision loss. Yet, routine monitoring is necessary, as the possibility of complications exists. In rare cases, the lesions progress to involve continued modification and degeneration of the retina, RPE and choroid. In addition, subsequent neurosensory retinal detachment has been observed; however intervention is still seldom necessary. 14 Risk of choroidal neovascular membrane formation is likely non-existent as development has only been documented in cases of concurrent maculopathies, such as degenerative conditions of the macula. 2 Annual to semi-annual monitoring is recommended, 14 with testing ranging among fundus examination, OCT and macular threshold perimetry. The patient can self-monitor for any visual change with a home Amsler grid. In cases of large lesions or the presence of pigment clumping, more frequent observation may be warranted. 14 CONCLUSION Given torpedo maculopathy is a rare and poorly understood condition, it may pose a diagnostic dilemma. Our patient exhibited the funduscopic diagnostic criteria of torpedo maculopathy and OCT findings consistent with a discrete choroidal excavation and associated subretinal cleft, which correlate with the more recent literature findings. It has been speculated that the variable appearances of torpedo lesions as observed with OCT represent Figure 8. En face optical coherence tomographic angiography (OCTA) choroidal vasculature segmentation of the right macula, imaged with Cirrus HD-OCT. Decreased flow is observed corresponding to the OCT subretinal cleft, in addition to surrounding hyper-reflectivity corresponding to the tail of the lesion Optometry Australia Clinical and Experimental Optometry November

6 Figure 9. Optical coherence tomographic angiography (OCTA) choroidal vasculature segmentation of the left macula, imaged with Cirrus HD-OCT. The scan reveals a normal, dense homogenous image. different stages of the same disease that evolve over several decades. 15 Even more recently, OCTA findings have shown how the torpedo lesion affects the overall choroidal vasculature. Further evaluation of OCT and OCTA findings may aid in the advanced understating of this condition. ACKNOWLEDGEMENTS This work was presented as a poster, entitled Torpedo maculopathy and focal choroidal excavation: two rare entities presenting concomitantly, at Optometry s Meeting in Boston, Massachusetts on 2 July REFERENCES 1. Roseman RL, Gass JD. Erratum. Arch Ophthalmol 1992; 110: Pian D, Ferrucci S, Anderson SF et al. Paramacular coloboma. Optom Vis Sci 2003; 80: Golchet PR, Jampol LM, Mathura JR Jr et al. Torpedo maculopathy. Br J Ophthalmol 2010; 94: Trevino R, Kiani S, Raveendranathan P. The expanding clinical spectrum of torpedo maculopathy. Optom Vis Sci 2014; 91: S71 S Sanabria MR, Coco RM, Sanchidrian M. OCT findings in torpedo maculopathy. Retina Cases Brief Rep 2008; 2: Thomas AS, Flaxel CJ, Pennesi ME. Spectraldomain optical coherence tomography and fundus autofluorescence evaluation of torpedo maculopathy. J Pediatr Ophthalmol Strabismus 2015; 52: e8 e Shields CL, Guzman JM, Shapiro MJ et al. Torpedo maculopathy at the site of the fetal bulge. Arch Ophthalmol 2010; 128: Richez F, Gueudry J, Brasseur G et al. [Bilateral torpedo maculopathy]. J Fr Ophtalmol 2010; 33: Sharma S, Naqvi A, Cruess AF. Bilateral macular colobomas. Can J Ophthalmol 1996; 31: Tsang T, Messner LV, Pinol A et al. Torpedo maculopathy: In-vivo histology using optical coherence tomography. Optom Vis Sci 2009; 86: E1380 E Wong EN, Fraser-Bell S, Hunyor AP et al. Novel optical coherence tomography classification of torpedo maculopathy. Clin Exp Ophthalmol 2015; 43: Papastefanou VP, Vázquez-Alfageme C, Keane PA et al. Multimodal imaging of torpedo maculopathy with swept-source, en face optical coherence tomography and optical coherence tomography angiography. Retin Cases Brief Rep 2016; doi: /ICB Margolis R, Mukkamala SK, Jampol LM et al. The expanded spectrum of focal choroidal excavation. Arch Ophthalmol 2011; 129: Su Y, Gurwood AS. Neurosensory retinal detachment secondary to torpedo maculopathy. Optometry 2010; 81: Cullen C, Zaborowski AG. A case report of torpedo maculopathy in an African boy. J AAPOS 2013; 17: Clinical and Experimental Optometry November Optometry Australia