Aims To compare optical coherence tomography (OCT) features of active necrotising infectious retinitis (NIR) due to toxoplasmosis or herpesviruses and to determine distinctive OCT signs for these two causes of infectious retinitis.
Methods OCT scans from eyes with active NIR due to varicella zoster virus (VZV), herpes simplex virus (HSV), cytomegalovirus (CMV), and toxoplasmosis (TOXO) were reviewed. All images were evaluated for the presence of previously described OCT findings in TOXO-NIR and compared with the viral group. New OCT findings were recorded and compared. Retinal and choroidal thickness were measured at the site of NIR and compared.
Results 10 eyes diagnosed with TOXO-NIR and 13 eyes affected by viral-NIR (9 CMV and 4 VZV) were analysed. All eyes showed full thickness hyper-reflectivity, disruption of the retina and a variable degree of vitritis. Among previously described OCT signs, hyper-reflective oval deposits and hypo-reflectivity of the choroid had a higher prevalence in TOXO (p=0.018 and p<0.0001, respectively). Among the new signs, hyper-reflective round deposits along the posterior hyaloid, retrohyaloid hyper-reflective spots and a disruption of the choroidal architecture were more frequent in TOXO eyes (all p<0.01). Intra-retinal oedema and hyper-reflective vertical strips within the outer nuclear layer were suggestive of a viral aetiology (p=0.045). Retinal thickness at the site of NIR did not differ between the two groups. Choroidal thickness was significantly higher in TOXO eyes (p=0.01).
Conclusions The diagnosis of NIR is largely based on clinical and laboratory findings. OCT changes may be useful in differentiating different causes of NIR.
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Contributors AI: designed the work, acquired, analysed and interpreted the data, drafted the work, revised and gave final approval. AA: analysed and interpreted the data, drafted the work, revised and gave final approval. VR, CM, AR: acquired, analysed and interpreted the data, revised and gave final approval. GS, FV, PMC: interpreted the data, revised and gave final approval.
Competing interests GS has financial relations with OCT manufacturers including: Heidelberg Engineering, Zeiss, Nidek, Canon, Optovue.
Ethics approval Local IRB.
Provenance and peer review Not commissioned; externally peer reviewed.
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