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 Table of Contents  
CASE REPORT
Year : 2021  |  Volume : 33  |  Issue : 3  |  Page : 337-340

Abnormal electrophysiology in a case of torpedo maculopathy


Department of Vitreo Retina, Chaithanya Eye Hospital and Research Centre, Trivandrum, Kerala, India

Date of Submission08-Sep-2020
Date of Decision28-Apr-2021
Date of Acceptance30-Apr-2021
Date of Web Publication08-Dec-2021

Correspondence Address:
Dr. Akshaya Ashok
Chaithanya Eye Hospital and Research Centre, Kesavadasapuram, Trivandrum - 695 004, Kerala
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/kjo.kjo_138_20

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  Abstract 


Torpedo maculopathy is an uncommon, often isolated retinal finding reported in literature. We report a case of torpedo maculopathy with nystagmus and abnormal electroretinogram findings with an abnormal mutation in a child. This case highlights the need for a detailed evaluation including electrophysiology and genetic testing in this retinal pathology.

Keywords: Electrophysiology, RP1L1 mutation, torpedo maculopathy


How to cite this article:
Soman M, Ashok A, Mohan A, Nair U. Abnormal electrophysiology in a case of torpedo maculopathy. Kerala J Ophthalmol 2021;33:337-40

How to cite this URL:
Soman M, Ashok A, Mohan A, Nair U. Abnormal electrophysiology in a case of torpedo maculopathy. Kerala J Ophthalmol [serial online] 2021 [cited 2022 Oct 7];33:337-40. Available from: http://www.kjophthal.com/text.asp?2021/33/3/337/331921




  Introduction Top


Torpedo maculopathy is a rare, incidental retinal finding believed to a presumably congenital lesion involving the retinal pigment epithelium (RPE)[1] with primary choriocapillary loss.[2] Retinal laser ellipsometry analysis has revealed a kite-shaped region at the junction of superior arcuate, inferior arcuate, and papillomacular bundle to be the location of this finding, a region of embryologically sparse nerve fiber layers.[3] Other ocular comorbidity and genetic analysis of these patients however are scarcely detailed in the literature.[4],[5] We report a case of torpedo maculopathy associated with electrophysiological changes and genetic mutation not hitherto reported in literature.


  Case Report Top


A 5-month-old male child presented to our clinic with complaints of abnormal eye movements in both eyes noticed since birth. He was born of a full-term normal delivery with birth weight of 3.2 kg in a consanguineous family. There was no positive antenatal history. He was immunized for age and was diagnosed to have global developmental delay. On examination, he was fixing and following light and was noted to have large amplitude pendular nystagmus. Retinoscopy did not reveal any gross refractive error. Anterior segment examination was unremarkable with normal pupils in both eyes. Fundus examination revealed a large pale disc with myelinated nerve fibers inferior to the disc in both eyes. A torpedo-shaped hypopigmented atrophic patch with well-defined margins was noted inferotemporal to right eye fovea [Figure 1]. Flash visual evoked potential showed irregular waveforms and flash electroretinogram (ERG) revealed suppression of scotopic and photopic waveforms [Figure 2]. Optical coherence tomographic of the right eye [Figure 3] revealed type 1 pattern[6] with inner segment-outer segment irregularity, attenuation of the ellipsoid layer and interdigitation zone, RPE thinning and RPE choroidal excavation without any outer retinal cavitation. Pediatric neurology evaluation was done, and magnetic resonance imaging brain was normal. As a part of his systemic evaluation, chromosomal sequencing was done which revealed a heterozygous “variant of uncertain significance” variant in RP1sL1 gene [Figure 4]. Chromosomal evaluation of the parents and relatives could not be done. He was managed conservatively and followed up at 6 months interval.
Figure 1: Fundus picture of the right eye showing torpedo-shaped hypopigmented atrophic patch with well-defined margins inferotemporal to fovea

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Figure 2: (a) Flash electroretinogram revealed suppression of both scotopic and photopic waveforms suggestive of rod-cone dysfunction; ( b) Flash visual evoked potential showing abnormal irregular waveforms

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Figure 3: Optical coherence tomographic scan through torpedo maculopathy lesion showing normal inner retinal layers, outer segment abnormality with the loss of ellipsoid layer, interdigitation zone, retinal pigment epithelium thinning, and retinal pigment epithelium-choroidal excavation with no outer retinal cavitation (type 1 pattern)

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Figure 4: Chromosomal sequencing revealing a heterozygous “variant of uncertain significance” variant in RP1L1 gene

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  Discussion Top


We report a case of torpedo maculopathy with abnormal ERG findings associated with an RP1L1 mutation. Torpedo maculopathy is mostly an isolated retinal finding and is often reported as a stable pathology with recommended annual ocular follow-up. Reports of progression to retinal degeneration, retinal detachment, and choroidal neovascularization exist.[7],[8] Cases of torpedo maculopathy with reported mutations have other systemic manifestations consistent with the mutations including autistic features, mental retardation, tuberous sclerosis, and retinal astrocytomas.[4],[5] However, none of the reports have highlighted the role of electrophysiologic findings or associated ocular comorbidity.[7],[8] Naik et al. had observed that one of their patients with enhanced s-cone syndrome had a torpedo lesion.[9] However, patients with RP1L1 mutations[10] have associated occult macular dystrophy and abnormal ERG even though clinically documented pigmentary retinopathy may be absent. The association of torpedo lesion with this mutation, however, has not been reported.

With this report and review of the previous relevant reports, we would like to emphasize that it may be necessary to do electrophysiological tests and genetic analysis in patients who are diagnosed to have torpedo maculopathy. Identification of the abnormal electrophysiology and/or genetic mutation could help us identify ocular or systemic pathologies that may be associated and may help us understand the related embryological events. The association of torpedo maculopathy with this mutation may be a chance occurrence in this case unless proved otherwise. A pooled genetic analysis of the reported cases of torpedo maculopathy may probably help us better understand the genetic predisposition of these rare eyes.

In summary, this case highlights two important observations. Patients with torpedo maculopathy must be tested electrophysiologically as there could be occult retinal dystrophies. These patients should also be appropriately investigated systemically as they may be associated with neurologic abnormalities and genetic mutations.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Golchet PR, Jampol LM, Mathura JR Jr., Daily MJ. Torpedo maculopathy. Br J Ophthalmol 2010;94:302-6.  Back to cited text no. 1
    
2.
Soman M, Arun S, Gehlot A, Mohan R, Nair U.Mohan A. Indocyanine green angiography and multimodal imaging in a case of torpedo maculopathy. Indian J Ophthalmol 2020;68:1448-9.  Back to cited text no. 2
[PUBMED]  [Full text]  
3.
Dreher AW, Reiter K, Weinreb RN. Spatially resolved birefringence of the retinal nerve fiber layer assessed with a retinal laser ellipsometer. Appl Opt 1992;31:3730-5.  Back to cited text no. 3
    
4.
Alarcon-Martinez T, Khan A, Myers KA. Torpedo maculopathy associated with NEXMIF mutation. Mol Syndromol 2019;10:229-33.  Back to cited text no. 4
    
5.
Hansen MS, Larsen M, Hove MN. Optical coherence tomography of torpedo maculopathy in a patient with tuberous sclerosis. Acta Ophthalmol 2016;94:736-7.  Back to cited text no. 5
    
6.
Wong EN, Fraser-Bell S, Hunyor AP, Chen FK. Novel optical coherence tomography classification of torpedo maculopathy. Clin Exp Ophthalmol 2015;43:342-8.  Back to cited text no. 6
    
7.
Williams PJ, Salek S, Prinzi RA, Bergstrom C, Hubbard GB 3rd. Distribution patterns of torpedo maculopathy: Further evidence of a congenital retinal nerve fiber layer-driven etiology. Saudi J Ophthalmol 2019;33:260-7.  Back to cited text no. 7
    
8.
Soman M, Indurjar A, Nair U. Mohan A. Secondary choroidal neovascular membrane in a case of Torpedo maculopathy. Indian J Ophthalmol 2020;68:2499-500.  Back to cited text no. 8
[PUBMED]  [Full text]  
9.
Naik A, Ratra D, Banerjee A, Dalan D, Jandyal S, Rao G, et al. Enhanced S-cone syndrome – Clinical spectrum in Indian population. Indian J Ophthalmol 2019;67:523-9.  Back to cited text no. 9
[PUBMED]  [Full text]  
10.
Noel NC, MacDonald IM. RP1L1 and inherited photoreceptor disease: A review. Surv Ophthalmol 2020;65:725-39.  Back to cited text no. 10
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4]



 

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