Purpose:
To present 3D Fourier Domain Optical Coherence Tomography (OCT) analysis of a parafoveal intraretinal nematode in a 4-year old boy.
Methods:
A 4-year old boy presented with a low visual acuity in his right eye at our out-patient clinic. On examination his visual acuity was 5/10 in the right eye and 5/3 in the left eye (Tumbling E-optotypes). There were no signs of strabismus, and eye movements were full. Both anterior segments were unremarkable, as was the posterior segment of the left eye. Fundus examination of the right eye revealed a thready vitreous and a peculiar, elevated parafoveal lesion (see figure). With the 3D OCT-1000 (Topcon, USA) several 3D-OCT volume scans were made through the lesion. Post-acquisition a 3D-reconstruction was made of the area of interest. Serological testing and faeces examination was performed. A review of literature was undertaken.
Results:
The boy had not been outside the Netherlands, but a dog and guinea-pig were kept as pets. History revealed no recent mosquito or tick bites. Extensive serological testing and examination of the faeces remained negative for the presence of a nematode. OCT and fundus imaging however, showed a swelling of the parafoveal retina, surrounding a highly reflective, curled-up lesion, suggestive of a nematode. Given the aspect and dimensions of the nematode on a 3D OCT reconstruction and after extensive review of literature, a diagnosis of Dirofilaria immitis is most likely, although serological testing remained negative.
Conclusions:
OCT 3D volume scans assisted in the diagnosis of an intraretinal nematode in the right eye of a 4-year old boy. Serological testing and faeces examination failed to determine the exact nature of the nematode, but given the dimensions revealed in the reconstructed 3D OCT images an infestation with Dirofilaria immitis was most suggestive.
Keywords: imaging/image analysis: clinical • retina