full-thickness corneal transplant rejection; This literature-non-study case was reported in a literature article and describes the occurrence of TRANSPLANT REJECTION (full-thickness corneal transplant rejection) in a 51-year-old male patient who received mRNA-1273 (Moderna COVID-19 Vaccine) for COVID-19 vaccination.      The patient's past medical history included Keratoconus (Keratoconus in both eyes after penetrating keratoplasty in right eye in 1992), Glaucoma steroid-induced (Steroid induced Glaucoma in OD (right eye) presented with chronic graft failure and a best-corrected visual acuity of counting fingers.), Keratoplasty (penetrating keratoplasty (PK) in the right eye (OD)) in 1992, Keratotomy (Keratotomy in right eye) in 1994 and Corneal transplant (The decision was made to perform a repeat full-thickness transplant) in 2021.    On an unknown date, the patient received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) 1 dosage form. On an unknown date, the patient experienced TRANSPLANT REJECTION (full-thickness corneal transplant rejection) (seriousness criterion medically significant). At the time of the report, TRANSPLANT REJECTION (full-thickness corneal transplant rejection) outcome was unknown. Possible    DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On an unknown date, Corneal endothelial microscopy: abnormal (abnormal) Specular microscopy revealed an endothelial cell count of 712 in OD and 2710 in OS. On an unknown date, Visual acuity tests: 20/400 visual acuity was improved to 20/400 and abnormal (abnormal) reduction in visual acuity to hand motion (HM).     The action taken with mRNA-1273 (Moderna COVID-19 Vaccine) (Unknown) was unknown.   For mRNA-1273 (Moderna COVID-19 Vaccine) (Unknown), the reporter considered TRANSPLANT REJECTION (full-thickness corneal transplant rejection) to be possibly related.    Patient was started on postoperative steroid and antibiotic drops 4x a day. By postoperative week 2, the graft was clearing. On week 3 the patient received the first dose of Moderna vaccine. Within 3 days, the patient began developing eye pain, photophobia, and blurred vision and was found to have new graft edema with fine endothelial keratic precipitates indicative of early rejection. The topical steroid regimen was increased to every 2 hours while closely monitoring his steroid-responsive IOP. Despite a pulse of topical steroids, the graft demonstrated worsening central stromal edema by for more than 10 days. The transplanted tissue continued to fail with progressively worsening clarity despite steroid therapy and with a reduction in visual acuity to hand motion. Owing to a rising IOP on 3 medications, the topical steroid dosing was decreased to 4 times daily.  This case concerns a 51-year-old male patient with a relevant medical history of Keratoplasty with chronic graft failure and glaucoma undergoing treatment with 3 intraocular pressure-lowering agents, who experienced the unexpected serious event of Corneal graft failure after mRNA- 1273 Moderna vaccine (Moderna COVID-19 Vaccine / Spikevax). The onset of the event occurred approximately 3 days after the first dose of mRNA- 1273 vaccine. The patient had undergone corneal transplantation 3 weeks before vaccination. Clinical course included eye pain, photophobia, and blurred vision. The patient was found to have graft rejection with corneal oedema and endothelial keratic precipitates. Despite treatment with topical steroids, it evolved into graft failure. The rechallenge is not applicable due to the nature of the event. Prior graft rejection and use of glaucoma medications remain a confounder. The benefit-risk relationship of mRNA- 1273 vaccine / Moderna COVID-19 Vaccine is not affected by this report   Most recent FOLLOW-UP information incorporated above includes: On 03-Nov-2021: Follow up received by safety 04-Nov-2021 included an Email with FTA received from SARA team.; Sender's Comments: This case concerns a 51-year-old male patient with a relevant medical history of Keratoplasty with chronic graft failure and glaucoma undergoing treatment with 3 intraocular pressure-lowering agents, who experienced the unexpected serious event of Corneal graft failure after mRNA- 1273 Moderna vaccine (Moderna COVID-19 Vaccine / Spikevax). The onset of the event occurred approximately 3 days after the first dose of mRNA- 1273 vaccine. The patient had undergone corneal transplantation 3 weeks before vaccination. Clinical course included eye pain, photophobia, and blurred vision. The patient was found to have graft rejection with corneal oedema and endothelial keratic precipitates. Despite treatment with topical steroids, it evolved into graft failure. The rechallenge is not applicable due to the nature of the event. Prior graft rejection and use of glaucoma medications remain a confounder. The benefit-risk relationship of mRNA- 1273 vaccine / Moderna COVID-19 Vaccine is not affected by this report