The use of swept-source optical coherence tomography (SS-OCT) may provide findings that distinguish ocular toxoplasmosis in immunocompetent patients from etiologies of nontoxoplasmic retinochoroiditis, according to study results published in Eye. Such findings may include retinal hyperreflective round deposits, sublesional choroidal thickening, and sublesional retinal pigment epithelium elevation. 

A team of investigators conducted a prospective cohort study to characterize SS-OCT features that could isolate ocular toxoplasmosis from other forms of retinochoroiditis. 

They enrolled 43 patients (43 eyes) with active toxoplasmic retinochoroiditis and evaluated SS-OCT findings by comparing them with 54 eyes (54 lesions) with nontoxoplasmic retinochoroiditis. 


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Some reported conditions in eyes in the nontoxoplasmic retinochoroiditis cohort were Behçet disease (18 eyes; 33.33%), rickettsial disease (11 eyes; 20.40%), viral acute retinal necrosis (6 eyes; 11.11%), and fungal disease (6 eyes; 11.11%). 

Among eyes with toxoplasmic retinochoroiditis, typical active retinochoroiditis associated with chorioretinal scar was reported in 23 (53.4%) eyes and active retinochoroiditis without chorioretinal scar was reported in 20 eyes (46.5%). Eyes with toxoplasmic retinochoroiditis had unilateral uveitis more frequently than nontoxoplasmic eyes (P =.001).  

On comparing OCT findings in the 2 groups, eyes with toxoplasmic retinochoroiditis had a significantly higher prevalence for hyperreflective round-shaped deposits along the posterior hyaloid, retinal hyperreflective round deposits, sublesional retinal pigment epithelium elevation, choroidal hyperreflectivity, and sublesional choroidal thickening (P <.001 for each). Compared with nontoxoplasmic retinochoroiditis, eyes with toxoplasmic retinochoroiditis also had a greater prevalence for inner retinal layers hyperreflectivity (P =.04) and serous retinal detachment (P =.036). 

Hyperreflective round-shaped deposits, sublesional retinal pigment epithelium elevation, and sublesional choroidal thickening were all found to be significantly more likely in patients with ocular toxoplasmosis compared with nontoxoplasmic retinochoroiditis (positive likelihood ratios: 45.2, 23.86, and 9.79, respectively). 

In a 2-parameter model binary logistic regression, sublesional retinal pigment epithelium elevation (Wald=11.905; P <.001) and sublesional choroidal thickening (Wald=14.881; P <.001) were found to be significant predictors for diagnosing ocular toxoplasmosis. Diagnostic accuracy was improved with the addition of hyperreflective round-shaped deposits along the posterior hyaloid or the retinal surface, resulting in an area under the curve value of 0.96 for the 2-parameter model and 0.98 for the 3-parameter model. 

Some study limitations included the small sample size of the nontoxoplasmic cohort; the wide variety of entities included in the group, which did not allow separate analysis of the OCT findings for each etiology; and the lack of inclusion of immunocompromised patients with toxoplasmic retinochoroiditis who might have had different OCT changes. 

“In conclusion, this prospective study provides information regarding SS-OCT findings of active toxoplasmic retinochoroiditis as compared to non-toxoplasmic retinochoroiditis, and reveals several of these features as distinctive for ocular toxoplasmosis,” the researchers wrote. “SS-OCT, as well as [spectral domain]-OCT with [enhanced depth imaging] mode, is extremely useful in the diagnosis of acute toxoplasmic retinochoroiditis, particularly in the absence of associated old scar,” according to investigators. 

Disclosure: Multiple study authors declared affiliations with the biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.  

Reference 

Ksiaa I, Khochtali S, Mefteh M, et al. Distinguishing swept-source optical coherence tomography findings in active toxoplasmic retinochoroiditis. Eye. Published online June 11, 2021. doi:10.1038/s41433-021-01491-4