Name

La maculopathie en torpille: analyse multimodale d’une série de cas pédiatriques

Torpedo maculopathy (TM) was first described in 1992 as a focal congenital abnormality of the retinal pigment epithelium (RPE) consisting of an asymptomatic torpedo-like shape lesion located close and pointing to the temporal portion of the macula. We describe a series of children affected by TM and characterize this lesion in a multimodal way.

Children examined in our clinic between 2014 and 2019 and having presented with TM were retrospectively collected. Demographics, visual acuity, orthoptic evaluation, fundoscopy, fluorescein and ICG angiography, fundus autofluorescence, OCT, angio-OCT, automated visual field, microperimetry and retinal electrophysiology were analyzed.

Five children (3M : 2F), i.e. 2 RE, 3 LE, were included. Median age at the diagnosis was 4 years and all patients were asymptomatic. Visual acuity was symmetric after refractive correction with no significant unilateral amblyopia. Intermittent convergent strabismus was observed in one affected eye. Funduscopy of the majority of cases (3/5) revealed a classic, well-circumscribed hypopigmented torpedo-like chorioretinal lesion pointing to the fovea with a slightly pigmented temporal tail, located in the horizontal raphe. One case presented with the same clinical aspect (except choroidal excavation superimposed), but the TM lesion was located in the superior-temporal blood vessels and no ocular torsion was highlighted. The last one was typical in aspect and location, but much smaller than usual. Fluorescein and ICG angiography showed hyperfluorescence transmission due to RPE atrophy and no abnormal leakage. No autofluorescence was detected, except in the margin of the TM. Subfoveal disruption of the photoreceptor and RPE complex with thinning of the outer retinal layers and hyperreflective choroid was always seen on OCT. However, sub-retinal cavitation defect was not always present. In summary, three cases were classified on OCT as type 1 and two as type 2 according to Wong et al. classification. Angio-OCT did not show any variability in the vascularization of the retinal vascular complexes. Automated visual field and microperimetry revealed a paracentral scotoma in one case. Multifocal ERG highlighted a wave amplitude depression next to the TM in two cases and no inter-ocular amplitude asymmetry was observed on full-field ERG. Toxoplasma serology was negative in the majority of patients and maternal serology in two others. Parental fundoscopy was physiologic in all cases.

TM seems not to be always located exactly in the horizontal raphe and could be slightly upper deviated. Differential diagnosis includes torpedo-like lesion along the arcades associated with enhanced S-cone syndrome (ESCS) or with toxoplasma chorioretinitis. However, our patients had negative toxoplasma serology and no other retinal features compatible with ESCS. Furthermore, the two types of OCT presentation seem not to be linked to different evolution stages with sub-retinal cavitation cleft occurring later in life, as type 2 TM was diagnosed as early as in a four year old girl. Whether individual factors, or a combined mechanism of genetic markers, vascular supply, or congenital defect at a precise time during fetal development of the RPE contributes to the formation of TM is still unknown. TM is usually non-progressive, but some cases could be complicated by choroidal neovascularization. A regular follow-up is therefore recommended.

TM in a pediatric population appears to have variable clinical presentation. Lifelong follow-up is advised as choroidal neovascularization may occur.