Introduction Unexplained visual loss after removal of silicone oil from the eye has been described. The purpose of this study is to determine the incidence of unexplained loss of visual acuity after SO removal and to provide possible explanations for this phenomenon. Methods This retrospective study included patients that underwent vitreoretinal surgery, at Centro Hospitalar São João, between January of 2012 and October of 2018. Inclusion criterion was vitreoretinal surgery in which the chosen endotamponade was SO, followed by removal of SO and exchange with balanced salt solution (BSS) or air. After SO removal, patients with documented loss of best corrected visual acuity (BCVA) on two or more Snellen lines were analyzed and patients in which the cause of the visual loss was identified, namely OHT (intraocular pressure > 21 mmHg), retinal re-detachment, glaucoma, retinal proliferative membrane formation, or corneal decompensation, were excluded. All patients with unexplained visual loss underwent spectral domain optical coherence tomography (SD-OCT) to exclude causes of visual reduction such as cystoid macular edema, epiretinal membrane, or ellipsoid/interdigitation zone disruption. A p value less than 0.05 was considered statistically significant. Results A total of 46 eyes underwent SO tamponade and SO removal during the study period. In 34.8% of the cases ( n = 16) there was visual acuity loss in at least two Snellen lines. Of 46 eyes, 23.9% ( n = 11) showed vision loss due to known secondary causes. Unexplained loss of visual acuity after SO removal occurred in 10.9% of cases. OHT during silicone endotamponade ( p = 0.046) and silicone emulsification ( p = 0.001) were identified as factors associated with unexplained visual loss after SO removal. Conclusion Unexplained loss of visual acuity after SO removal occurred in 10.9% of cases. OHT during silicone endotamponade and SO emulsification were identified as important factors in the ethology of this phenomenon.

Purpose: To evaluate the visual function and architecture of the central and peripapillary retina in patients with inactive toxoplasmic retinochoroiditis outside the macular and peripapillary regions (zones 2 and 3). Methods: Cross-sectional study of 20 eyes (18 patients) with zone 2 and 3 toxoplasmic scars and visual acuity ≥20/25. Patients underwent Humphrey 10-2 perimetry, contrast sensitivity (Mars test), and color vision testing (L'Anthony desaturated D-15). The retinal nerve fiber layer (RNFL) and macular thicknesses were determined by optical coherence tomography. Results: The patients' mean age was 27.4 ± 10.3 years, and the mean duration of remission was 6.15 ± 5.19 months. Abnormal contrast sensitivity and color vision were observed in three (15.0%) and four eyes (20.0%), respectively. Mean deviation (MD) and pattern standard deviation (PSD) fell outside the 95% normal confidence limits of the perimeter's database in 14 (70.0%) and seven eyes (35.0%), respectively. Foveal and mean RNFL thicknesses were within the normal limits in all eyes. Eyes with zone 2 retinochoroiditis had lower foveal sensitivity than eyes with zone 3 lesions (p=0.041). Eyes with a longer duration of remission had a higher MD (r=0.575; p=0.013) and a lower PSD (r=-0.593; p=0.010). Conclusion: Despite normal central and peripapillary retinal architecture, eyes with inactive zone 2 and 3 toxoplasmic retinochoroiditis can present with abnormal color, contrast, and macular perimetric sensitivity. Zone 2 retinochoroiditis was associated with lower foveal sensitivity, and a longer duration of retinochoroiditis remission was associated with better perimetric parameters (MD and PSD). Keywords