Vitreal, retinal, and choroidal findings in active and scarred toxoplasmosis lesions: a prospective study by spectral-domain optical coherence tomography

The aim of our study was to investigate vitreal, retinal, and choroidal morphologic changes in active and scarred toxoplasmosis lesions using spectral-domain optical coherence tomography (SD-OCT). In this prospective study, 19 eyes of 15 consecutive patients with ocular toxoplasmosis were included. Complete ophthalmologic examination and SD-OCT were done at the initial visit and during follow-up. Retina and choroid SD-OCT protocols directed to macular area and lesions observed on clinical examination were used. Seventeen active lesions and 56 retinochoroidal scars were studied. In the acute phase, disruption, thickening, and hyper-reflectivity of the neurosensory retina with photoreceptor (PR) interruption and retinal pigment epithelial (RPE) elevation were found. The choroid became thickened and hyporeflective. During follow-up, neurosensory retinal layers thinning and disorganization, PR interruption, and RPE elevation and/or atrophy were demonstrated. The choroid returned to normal thickness and became more hyperreflective. Five active lesions presented with hyperreflective oval deposits within the vitreoretinal interface, adjacent to or far away from the lesions. During follow-up, the deposits became smaller, entered into the inner retina layers and faded with time until complete resolution. Multiple hyperreflective dots in the vitreous cavity, compatible with vitritis, and posterior hyaloid thickening were demonstrated in the acute phase, with complete resolution and detachment of the posterior hyaloid during follow-up. Four types of scars were specified according to outer retina-choroid interface changes; atrophic, elevated, deep, and combined (atrophic & elevated). Epiretinal membrane segments were found over active and scarred lesions. SD-OCT imaging showed toxoplasmic retinochoroidal lesions and scars to be complex and characterized acutely by thickening and disorganization of both the retina and underlying choroid, and following scar formation by varying degrees of thinning, often in conjunction with irregularity of the outer retinal layers.