Medical Oncologist
Emergency guidance
Sudden Vision Loss or Double Vision: — What to Do Right Now
New or sudden vision changes during cancer treatment are never something to wait out. They can be the first sign of a treatable emergency — and the window to act is short.
Medically reviewed by Dr. T. Raghavender Reddy, Medical Oncologist, MBBS · DM (Medical Oncology) · MD (Radiation Oncology) · Last reviewed August 2026
- Do not drive — If your vision has changed, call someone. You should not be behind the wheel.
- Act in minutes, not hours — Some causes of sudden vision loss are reversible if treated quickly and permanent if not.
- Tell your team what you are on — The drugs and radiation you are receiving change what the emergency team needs to rule out first.
- Both eyes or one eye matters — Which eye is affected — and what else is happening — helps your team triage immediately.
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Sudden vision loss or new double vision during cancer treatment can signal a stroke, brain metastasis, immune-related optic neuritis, or a reaction to your therapy. These are medical emergencies. Go to the nearest emergency department now, or call your oncology team's emergency line immediately. Do not wait to see if it improves on its own.
If a symptom below applies to you, do not wait for a callback. Call 1800-202-8726 or go to your nearest emergency department.
Meet the Specialists
17+ senior cancer specialists. One panel for your case.
Trained at AIIMS, Tata Memorial, and leading international centres. Combined 150+ years of experience. Every complex case is reviewed by 3+ of them — together.
Medical Oncologist
Dr. C. Raghavendra Reddy
MBBS(Gold Medal), DNB(General Medicine), DM(Medical Oncology)(Gold Medal)
Medical Oncologist
Dr. Bharati Devi Gorantla
MBBS, MD(General Medicine), DM(Medical Oncology)(Adyar,Chennai), ECMO, MRCP SCE(UK)
Medical Oncologist
Dr. Owais Mohammed
MBBS, MD (General Medicine), DrNB (Medical Oncology), ECMO, MRCP SCE (Medical Oncology) (UK)
Medical Oncologist
Medical Oncologist
Surgical Oncologist
Dr. Muralidhar Muddusetty
MBBS (AIIMS), MS (Surgery) (AIIMS), DNB (Surgical Oncology), MRCS (Edinburgh)
Surgical Oncologist
Surgical Oncologist
Surgical Oncologist
Dr. Vinay Mamidala
MBBS, MS(General Surgery), M.Ch(Surgical Oncology), FMAS, FARIS(Ongoing)
Surgical Oncologist
Radiation Oncologist
Radiation Oncologist
Radiation Oncologist
Hematologist
Interventional Radiologist
Dr. Mohammed Imran
Surgical Oncologist
Dr. Vajja Sandeep Kumar
MBBS, MS (General Surgery), DrNB (Surgical Oncology), FALS Oncology
Surgical Oncologist
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Not sure whether this counts as an emergency?
Call the helpline. It is always better to check than to wait.
What should I do right now?
- Stop what you are doing and sit or lie down somewhere safe.
- Call someone — you must not drive yourself to hospital.
- Call your oncology team's emergency number right now.
- If you cannot reach your team, go directly to the nearest emergency department.
- Note which eye or eyes are affected and describe what the vision is like — blurred, dark, double, or a curtain.
- Note the exact time the change started.
- Note any other symptoms: headache, dizziness, weakness, confusion, or nausea.
- Tell the emergency team you are on cancer treatment and name every drug you are taking.
- Do not take any extra medication without being told to.
Is what you are experiencing an emergency or urgent?
| What you notice | Emergency — go now | Urgent — call oncology today |
|---|---|---|
| Vision in one or both eyes | Sudden, complete or near-complete loss | Gradual blurring that has worsened over several days |
| Double vision | With headache, confusion, or limb weakness | Mild, in one direction only, started gradually, no other symptoms |
| Headache alongside vision change | Sudden and severe — the worst of your life | Mild to moderate, not sudden in onset |
| Duration before you are reading this | Seconds to minutes — even if vision returned | Slowly worsening over days to weeks |
| Other neurological signs | Arm weakness, facial drooping, or speech change | None |
| Typically starts | Any time during or after treatment — no warning | Often gradual with drug-related eye toxicity |
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Next step
Still not sure what applies to you?
Send your reports across and a senior medical oncologist will go through what they mean, what is known, and what the options actually are.
Common questions
Frequently asked questions
Can cancer treatment itself cause sudden vision changes?
Yes, and this is important to tell the emergency team. Immunotherapy drugs can cause inflammation of the optic nerve or the eye. Some targeted therapies and hormonal treatments are associated with changes to the retina. Radiation to the head or eye area can injure the optic nerve, sometimes months after treatment ends. Anti-VEGF drugs used in some cancers have been associated with a rare syndrome affecting the blood vessels supplying the brain and eyes. Name every drug you are taking so the team can consider these causes alongside stroke and brain metastasis.
Could sudden vision change mean brain metastases?
It is one possibility the team will assess. A new lesion in the brain can affect vision depending on where it sits — in the visual cortex, the optic pathways, or the areas that control eye movement. Tell the emergency team your cancer diagnosis and where the primary cancer is. Do not assume it is or is not metastases — let the imaging decide. The treatment decisions depend on what the scan shows.
My vision came back after a few minutes. Do I still need to go to hospital?
Yes, go immediately. Temporary vision loss that returns — sometimes called amaurosis fugax — can be a warning that a stroke or vascular event is about to happen. The brief return of sight does not mean the danger has passed. Stroke guidance from bodies including WHO is clear that transient vision loss should be assessed as an emergency, and this applies to people on cancer treatment as much as anyone else. Go now, even if you feel completely normal.
What will happen when I arrive at the emergency department?
You will be assessed urgently. The team will check your neurological status, blood pressure, and eye reflexes. Depending on what they find, you will likely have a brain scan — usually a CT first, sometimes followed by an MRI — and blood tests. An ophthalmologist may be asked to review you. Tell the team your cancer diagnosis, the drugs you are on, and the exact time the symptom started. The more precise you can be about timing, the faster they can work.