Purpose To report a case of central retinal vein occlusion (CRVO) seven days following the first dose of ChAdOx1 nCoV-19 vaccine and propose a hypothesis for the possible underlying pathogenesis. Observation A 31-year-old male presented with CRVO with cystoid macular edema, one week after receiving his first ChAdOx1 nCoV-19 vaccine dose. Apart from mild hyperhomocysteinemia, no major thrombophilic or systemic risk factors were found. Anti-platelet factor 4 antibodies, specific for vaccine-induced immune thrombotic thrombocytopenia, were also negative. However, he tested strongly positive (> 250 U/mL) for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) IgG spike antibodies, 2 weeks post the first dose – suggestive of a prior subclinical infection. Conclusion COVID-19 is known to be associated with an altered host one-carbon metabolism resulting in hyperhomocysteinemia. We hypothesize that a prior subclinical infection with COVID-19, the first hit, may have led to hyperhomocysteinemia in our patient and vaccination must have been the second hit that triggered the thrombotic event. Further studies, including correlation of thrombotic complications with IgG antibody titres post-vaccination, are essential in order to better understand the pathogenesis of such events.

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Background Uveal metastasis is reported to be the most common intraocular malignancy. The most common site of origin of ocular metastases in females is the breast. In some cases, uveal metastatic lesions respond to systemic chemotherapy. We report a case of a patient who developed choroidal metastasis, while on endocrine therapy with selective estrogen receptor modulator (SERM), tamoxifen, for estrogen receptor (ER) positive, progesterone receptor (PR) positive and (human epidermal growth factor receptor 2) HER2 negative primary breast carcinoma, which then regressed following systemic chemotherapy with palbociclib. Case description An 83-year-old female, with a history of modified radical mastectomy, chemotherapy and radiation therapy for infiltrating duct carcinoma of the breast, presented with a choroidal metastatic lesion in the left eye along with liver and lung metastases, 3 years after the primary carcinoma was treated. At the time of presentation, she was on tamoxifen. The choroidal tumor showed regression after the introduction of palbociclib, a cyclin-dependent kinase 4/6 (CDK4/6) inhibitor. Conclusion This report highlights the use of palbociclib, in the palliative treatment of choroidal metastasis from primary breast cancer. The use of chemotherapy for choroidal metastasis can help avoid external beam radiation therapy and its concurrent side effects. Although there are a few reports involving the use of palbociclib for metastatic breast carcinoma, all of those have been in conjunction with and/or following non-response to other treatment modalities. Ours is the first report wherein palbociclib has been used as the first-line palliative chemotherapy and helped in regression of choroidal metastasis.

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