Measurement of the active toxoplasma retinochoroiditis lesion size during the disease course with swept-source optical coherence tomography angiography: A retrospective image analysis.

purposeTo measure the lesion size reduction in eyes with active toxoplasma retinochoroiditis during the disease course with swept-source optical coherence tomography angiography (SS-OCTA).

methodsWe retrospectively analysed the chorioretinal lesion size in a group of 14 eyes with a single active toxoplasma retinochoroiditis lesion. SS-OCTA was performed at the baseline and follow-up in all eyes. The 6 × 6 mm choriocapillaris slab images were evaluated with image analysis (MATLAB). The number of black and white pixels in a 1500-µm-diameter circle centred on each active lesion was counted at the time of baseline examination and at the first follow-up visit when the chorioretinal scar formation was noticed.

resultsFourteen eyes with a single active toxoplasmosis retinochoroiditis lesion were included. Ten patients were female and three were male. The mean age was 29.1 ± 14.9 years. Active lesions were at the macula in five eyes, at the periphery in six eyes and juxtapapillary in three eyes. At the initial examination, the lesion area was observed as an area with a decreased flow signal on SS-OCTA. There was the perilesional capillary disruption in superficial and deep capillary plexi together with a diffuse capillary network attenuation and non-detectable flow signal zones in the choriocapillaris slabs. In addition to sulfamethoxazole-trimethoprim and azithromycin combination, oral corticosteroids were only co-administered in five (35%) eyes with macular involvement. The chorioretinal scar formation was observed in 4 to 16 weeks. At the time of inactivity, the original lesion was diminished in size when compared to its baseline in all study eyes (p = 0.001) with a mean black pixel reduction percentage of 21.8%. The reduction was 15.4% in eyes with macular lesion, 31.6% with peripheral lesions and 18.1% with juxtapapillary lesions (p = 0.001, p = 0.032, p = 0.028, p = 0.043, respectively). Visual acuity was correlated with black pixel reduction percentage in eyes with macular lesion (r = 0.56, p < 0.001).

conclusionHealing of the active toxoplasma retinochoroiditis lesion size could be monitored with an OCTA-based image analysis technique. Interestingly, the reduction in the lesion size was lesser in the macular lesions than the peripheral and juxtapapillary lesions following the treatment and this might contribute to the poorer visual outcomes observed in eyes with macular lesions.