This spontaneous report received from a patient and concerned a 59 year old white female of Not Hispanic/Latino origin.The patient's height, and weight were not reported. The patient's past medical history included: traumatic brain injury (date unspecified), and migraine (date unspecified), and concurrent conditions included: diverticulitis, non-alcohol user, non-smoker, food allergy and food sensitivity, allergy to Magnetic resonance imaging (MRI) dyes (hives), drug allergy (Omnicef-300). She had a traumatic brain injury in the past (date unspecified) with vestibular damage and wore prisms in her glasses and had been seeing a neuro-optometrist regularly. Patient had no drug abuse or illicit drug usage. The patient received covid-19 vaccine ad26.cov2.s (suspension for injection, route of admin not reported, batch number: 1805020, and expiry: 23-AUG-2021) dose was not reported, dose number in series was 01, 01 total was administered on 28-MAR-2021 for prophylactic vaccination to the left arm. No concomitant medications were reported.  On 28-MAR-2021 she experienced low grade body fever, chills, body ache, felt like a train hit her within minutes of injection and was exhausted. She drank tea that night and the next day (29-MAR-2021) she felt fine but was a little tired. She felt normal within 12 hours past injection. On an unspecified date, the patient experienced seeing flashes of light and blurriness. Her eye symptoms started to get worse and when she looked at her sewing plates (she did sewing on a regular basis) she had difficulty seeing the design (date unspecified). She booked an appointment with her neuro-optometrist on 12-OCT-2021 and the optometrist dilated her eyes and did couple of different images from her eyes (the patient noted that she did the test herself rather than staff doing it and that was alarming to her). The optometrist mentioned that she had edema in her eyes and wanted her to see a retinal specialist immediately and booked an appointment with an eye specialist on 13-OCT-2021. On 13-OCT-2021, the specialist injected Intravenous (IV) dye (not other wise specified) and did images of her eyes and diagnosed her with retinal vein occlusion and macular edema. The patient also had diagonal vision loss and saw floaters (on unspecified dates) and the specialist explained it as blood collecting behind her eye ball. She was provided the option of eye injection with Lucentis (ranibizumab) or surgery but was mentioned that injection would provide better results. The patient agreed and she had the injection the same day (13-OCT-2021) and also was given moistening eye drops (not otherwise specified). The patient went back every 04 or 06 weeks (she was not exactly sure) for a series of 05 injections of Lucentis. The second injection was a bit more painful but the test prior to the injection (name and date not specified) showed that the edema was going down and she had difficulty with the balance which was explained as because of the reduction of the fluid behind the eye ball. The third injection was a few days before new year's eve (unspecified date in DEC-2021) and the caller mentioned that she was scared of the pain she experienced during the second shot and the specialist suggested that she would close her eyes for 08 hours and only to open up to instill new lubricating eye drops (not otherwise specified) to prevent eye infections. That time around, it was less painful and with less sensitivity. The tests (name and date not specified) showed that the edema was down but there were still fluid there. The specialist gave the option of either to continue with the injection or to monitor and watch. The patient decided to continue with the injections because she had seen the results. She also mentioned that she has experienced high blood pressure (date unspecified) and was under monitoring by her specialists (because she had diverticulitis) and they told her that what she experienced was like having a blood clot. The patient mentioned that she did not want to say that this was because of the vaccine but she was scared that a booster dose may bring the eye symptoms again.The action taken with covid-19 vaccine ad26.cov2.s was not applicable. The patient recovered from felt like train hit within minutes of injection, body ache, chills, exhausted, little tired, and low grade body fever on 29-MAR-2021, was recovering from saw flashes of light, retinal vein occlusion, macular edema, and blood collecting behind eye ball, and the outcome of high blood pressure and difficulty with balance was not reported.This report was serious (Other Medically Important Condition).Sender's Comments: 20220126347-covid-19 vaccine ad26.cov2.s -Retinal vein occlusion,macular edema ,blood collecting behind eye ball. This event(s) is considered unassessable. The event(s) has a compatible/suggestive temporal relationship, is unlabeled, and has unknown scientific plausibility. There is no information on any other factors potentially associated with the event(s).