Optometry - Journal of the American Optometric Association
Volume 81, Issue 8 , Pages 405-407, August 2010

Neurosensory retinal detachment secondary to torpedo maculopathy

  • Yu Su, O.D.

      Affiliations

    • Corresponding Author InformationCorresponding author: Yu Su, O.D., 1200 West Godfrey Avenue, Philadelphia, Pennsylvania 19141.
    • ,
  • Andrew S. Gurwood, O.D.

The Eye Institute of the Pennsylvania College of Optometry at Salus University, Philadelphia, Pennsylvania

Article Outline

Abstract 

Background

Torpedo maculopathy has been characterized as a congenital retinal pigment epithelial (RPE) nevus.

Case

A 38-year-old black woman presented with a chief complaint of intermittent floating spots in the right eye of 7 months' duration. Dilated fundoscopy found a “torpedo-shaped” lesion, with the tip of the lesion pointing toward the temporal macula. Visual field testing found a paracentral nasal defect, and optical coherence tomography (OCT) found a sensory retinal detachment.

Conclusion

This lesion was unique because of the visibly detectable alterations seen in the photoreceptor layer of the retina and retinal pigment epithelium (RPE) in the setting of what was confirmed as a neurosensory retinal detachment. Torpedo maculopathy, although benign, may be visually devastating if its neurosensory etiopatholgy involves the macula. Even so, it rarely requires intervention.

Keywords: Torpedo maculopathy, Congenital RPE nevus, Paramacular coloboma, Retinal albinotic spot, Neurosensory retinal detachment, Optical coherence tomography (OCT)

 

Torpedo maculopathy (TM) is a rare condition that has been reported in English-language literature sporadically since 1989.1, 2, 3, 4, 5, 6, 7, 8, 9 The condition has been described as a solitary hypopigmented nevus of the retinal pigment epithelium in the vicinity of the macula,1 a solitary retinal albinotic spot,2 a congenital hypomelanotic freckle,2 and a paramacular coloboma.4 Although the name may be variable, the characteristic physiologic descriptions are similar: a “torpedo-shaped” lesion located directly temporal to the macula, typically presenting unilaterally but with the potential for bilaterality,8 absent of symptoms, has findings that are not associated with choroidal neovascularization, and the lesion typically remains stable.1, 2, 3, 4, 5, 6, 7, 8, 9

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Case report 

A 38-year-old black woman presented to the clinic with the chief complaint of seeing floaters occasionally in the right eye for the prior 7 months. Her best-corrected entering visual acuities were 20/20 in both eyes. External examination findings were normal with no evidence of visual field loss on confrontation testing or relative afferent pupillary defect. Refraction uncovered a stable spherical myopia measuring -3.00 diopters, in both eyes (OU). Biomicroscopy found normal anterior segment structures, with Goldmann applanation tonometry measuring intraocular pressures of 16 mmHg, OU. Dilated fundoscopy found a pigmented epithelial alteration located 1 disc diameter (DD) temporal to the fovea possessing a circumlateral pigmentary boarder (see Figure 1). The surrounding retinal/choroidal tissues and periphery of both eyes were normal. A central 24-2 visual field (VF) uncovered a paranasal depression corresponding to the lesion, in the right eye (O.D.). Optical coherence tomography (OCT) found a sensory retinal detachment with overlying thinning of the retina, photoreceptor loss, and disruption in the underlying retinal pigment epithelium (RPE)/Bruch's complex. Diffuse high reflectivity in the overlying retina indicated the potential for some interruption in the neurosensory retina (see Figure 2). Based on the constellation of signs and classic pathognomonic appearance, “torpedo” maculopathy was diagnosed. The diagnosis was confirmed by a retina specialist. Consistent with the benign nature of the lesion and absence of choroidal neovascularization, the patient was educated and advised to undergo a plan of continued, regular semiannual monitoring.

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Discussion 

Roseman and Gass1 and Gass2 classified these “torpedo” shaped lesions found in the vicinity of the macula as solitary congenital albinotic spots of the retinal pigment epithelium (CASRPE). Gass2 postulated the defect was characterized by a focal area of intact, nonpigmented RPE in combination with normal choroid and normal overlying retina.2 Daily (in Teitlebaum et al.3) later offered the term torpedo maculopathy because of its characteristic shape and invariant location.

Given the rarity of the condition, to date, only isolated case reports have been published.1, 2, 3, 4, 5, 6, 7, 8, 9 In his published work, Pian et al.4 used the name paramacular coloboma and hypothesized the cause to be from “incomplete differentiation of the arcuate bundles during development along the horizontal raphe of the macular architecture.” Teitelbaum et al.3 suggested the pathology was related to a “disturbance of the short posterior ciliary arteries and veins before birth,” producing an overlying RPE disruption to form a “torpedo-appearing” lesion.

All of investigators1, 2, 3, 4, 5, 6, 7, 8, 9 agree on the common point that “torpedo” maculopathy is a stable congenital embryonic defect in which functional visual loss is unlikely and where progression of any kind is rare.1, 2, 3, 4, 5, 6, 7, 8, 9 Until recently, in published case reports6, 7 containing evidence of structural changes of the lesions investigated through the modality of an OCT, “torpedo” maculopathy was neither found nor speculated to present with neurosensory retinal detachment or structural alterations within the retina, RPE, or choriocapillaris.

Sanabria et al.6 presented 2 cases of “torpedo” maculopathy. In both instances, the patients were teenagers who had demonstrated asymptomatic VF abnormalities corresponding to their retinal lesions.6 One case was a small, homogeneous, hypopigmented, classic “torpedolike” lesion with the OCT disclosing a faint thinning of the retinal tissues above the lesion with hyper-reflective signals in the RPE and choriocapillaris layers.6 The other case was described as a lager lesion with a distinctive hyperpigmented, asymmetric temporal border showing retinal thinning and an absence of the photoreceptor layer with a shallow neurosensory retinal detachment and irregular hyper-reflective signal in the RPE, more visible in the choroid.6 In contradistinction, pathophysiologically, Roseman and Gass1 theorized that these hypopigmented nevi possessed unusually appearing but essentially normal retina and choroid. Evidence of this was produced from examination of tissue obtained in autopsy of an amelanotic nevus in the peripheral fundus.2

Our case seems to support the alternate opinion, agreeing with the investigators who assert that some retinal/choroidal tissue modifications do occur. OCT inspection confirms retinal degeneration similar to that seen in the case by Sanabria et al.,6 clarifying the position that “torpedo” maculopathy has a unique set of characteristics that distinguishes it from the family of solitary hypomelanotic and albinotic nevi (CASRPE) first categorized by Gass.2

Further, Shields et al.10 discussed evidence of retinal thinning and photoreceptor loss in 10 consecutive patients, including 2 nonpigmented (nonmacular region) variants. In this series, there was no evidence of subretinal fluid in any of the subjects. This finding is important because it infers that TM deserves consideration as an independent entity, not fitting into the category of depigmented or atrophic forms of congenital hypertrophy of the retinal pigment epithelium (CHRPE). In light of these findings, perhaps the theories of Teitelbaum et al.,3 which recognize the idiosyncrasies of development, are plausible; TM is an embryonic vascular disturbance that might continuously stimulate RPE cells, leading to structural disorganization later in life.

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Differential diagnoses 

Toxoplasmic retinochoroiditis is the result of a parasitic disease caused by the protozoan Toxoplasma gondii.12 The primary host is the domestic feline (cat). The disease presents as a focal necrotizing chorioretinitis accompanied by vitreous inflammation. Typically, active disease involves an 8- to 16-week evolutionary period and results in circular-shaped hyperpigmented scarring in the areas affected. Recurrence of the infection is plausible and attributable to replication of the organism, which is in a cystic form at the edge of the scars.12 Suspected patients should be tested for the presence of Toxoplasma-specific IgG and IgM antibodies.

Idiopathic central serous chorioretinopathy or sick RPE syndrome is a condition that affects young individuals between the ages of 20 and 50 years. It predominantly affects men more than women by a ratio of 10:1.17 There also seems to be an association with “type-A” psychological factors.17 Stereoscopic binocular indirect biomicroscopy shows round or oval, clear to yellow or yellow-grey circumscribed lesions representing a serous elevation of the neurosensory retina and or detachment of the RPE.17 Diagnosis is confirmed by finding a hyperopic refractive shift, the occasional complaint of purple photopsias, classic OCT interpretation,18 and fundus fluorescein angiography (FA). Sick RPE syndrome or “gutter” syndrome is marked by chronic RPE changes in close proximity to the serous leakage. The pattern of RPE damage sometimes assumes a linear geometry consistent with the effects of gravity. Because the classic history surrounding the disease process is pathognomonic and any pigmentary scar formation is either circular or vertical, this entity is seldom confused with TM.

Intraocular tumors may be confused with nonpigmented RPE or choroidal nevi, metastatic carcinoma, or other nodular lesions of the choroid.11 Choroidal tumors appear as pigmented or nonpigmented lesions deep to the neurosensory retina. In early stages, the neurosensory retinal structure, although elevated secondary to being mechanically pushed up from subretinal processes, is typically normal. Later, as these tumors become infiltrative, they create changes to the tissues they invade. Other signs include overlying retinal drusen and orange pigmentation, RPE alteration, subretinal fluid accumulation, and choroidal neovascularization.13, 14 B-scan ultrasonography, FA, and OCT are both useful in the initial diagnostic phase as well as for monitoring the lesions over time.13, 14 The appearance of these lesions is distinctive, with little doubt regarding the process.

Presumed ocular histoplasmosis syndrome is an inflammatory syndrome associated with the systemic fungal infection Histoplasma capsulatum.15 It is characterized by a triad of classic eye signs: discrete atrophic peripheral chorioretinal scars, peripapillary atrophy, and macular or paramacular chorioretinal scarring in the absence of uveitis/vitritis.15 The peripapillary changes are thought to represent the processes of a failed choroidal neovascular membrane, and the “punched-out” lesions are thought to represent areas of hematogenous seeding of H. capsulatum to the retina producing deep tissue destruction.16 The peripheral “punched-out” chorioretinal scars may also represent small envelopes of choroidal neovascularization that have spontaneously regressed.15, 16

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Conclusion 

Torpedo maculopathy should be given due consideration as a unique entity within the category of focal congenital anomalies of the RPE. We suggest it not be placed within the subcategories of nonpigmented CHRPE or CASRPE.

Given the nature of these lesions as proposed by Teitelbaum et al.3 and the structural abnormalities exposed by the OCT, it is recommended that patients with large lesions, having irregular pigmented clumps with “fish-tails,” be observed with greater frequency using fundus photography and macular threshold perimetry. Fluorescein angiography and OCT may also be useful whenever there is a perceived or measured change in the size or shape of an observed lesion or in cases in which the patient realizes a change in the severity or frequency of symptoms.

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References 

  1. Roseman RL, Gass JDM. Solitary hypopigmented nevus of the retinal pigment epithelium in the macula. Arch Opthalmol. 1992;110(10):1358–1359
  2. Gass JDM. Focal congenital anomalies of the retinal pigment epithelium. Eye. 1989;3(1):1–18
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PII: S1529-1839(10)00309-X

doi:10.1016/j.optm.2010.06.001

Optometry - Journal of the American Optometric Association
Volume 81, Issue 8 , Pages 405-407, August 2010

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