The short answer
This is often the first question after a diagnosis. The NHS says it is normal to worry about how much your vision might change.
The NHS also says that if glaucoma is found and treated early, it may not change your vision much. Sometimes sight is affected, and in rare cases people lose their sight.
The National Eye Institute says early treatment can often stop the damage and protect your vision. MedlinePlus says glaucoma can usually be controlled. Without treatment, glaucoma can eventually cause blindness. That is why treatment matters.
What treatment can and cannot do
Treatment cannot undo damage that has already happened. The National Eye Institute says this clearly. Health New Zealand explains that existing damage to the optic nerve is permanent.
Treatment can stop your vision getting worse. The National Eye Institute says eye drops lower the pressure in the eye and prevent damage to the optic nerve.
This is why finding glaucoma early matters, and why treatment continues for life.
Source: US National Eye Institute · US National Eye Institute · Health New Zealand | Te Whatu Ora
How glaucoma affects sight
The National Eye Institute says vision loss usually starts with side vision, especially the part closest to the nose. Because it happens so slowly, many people cannot tell at first that their vision is changing.
MedlinePlus says that, without treatment, side vision is slowly lost. It can seem like looking through a tunnel. Over time, straight-ahead vision can also decrease.
This is why regular eye tests matter. They can find changes before you notice them.
Source: US National Eye Institute · MedlinePlus (US National Library of Medicine)
What helps protect your sight
- Use your drops every day, as prescribed. The National Eye Institute says that if you do not use them as prescribed, you could lose your vision.
- Keep every check-up. The NHS says it is important not to miss these appointments. They check that your treatment is working.
- Tell your doctor about side effects. The National Eye Institute says you may be able to use a different dose or a different medicine.
- Tell your doctor about other medicines, supplements and vitamins that you take.
The National Eye Institute says some people stop using their drops after a while. They forget, get out of the habit, or think the medicine is not helping. But the drops do not make you feel different or improve your vision. They prevent your vision from getting worse.
Source: NHS · US National Eye Institute
When to get help urgently
Source: NHS · NHS · US National Eye Institute
If your sight is already affected
The NHS says that sight loss can be difficult to come to terms with, and that a support group for people with sight loss can help. Help is available:
- Local support services. The NHS says that if you have long-term vision loss, your ophthalmologist or GP should refer you to local services that help you adapt.
- Practical support. The NHS lists help with adapting your home, low vision aids and technology for reading and phones, help with travel, advice on benefits, and talking therapies.
- Small changes at home. The National Eye Institute suggests brighter lights, anti-glare sunglasses, and a magnifying lens for reading.
- Charities. The NHS names Glaucoma UK and RNIB for information and support.
- Vision rehabilitation. The National Eye Institute suggests asking your doctor about vision rehabilitation services or devices that could help.
Source: NHS · NHS · US National Eye Institute · US National Eye Institute
How Emma can help
Emma is a companion for life with glaucoma. She lives on your phone.
- Spoken reminders for your drops and your appointments, so the daily routine is easier to keep.
- A Journey Log for your eye-pressure readings and notes, with a summary for your appointment.
- Answers in plain English, typed or spoken, read aloud if you prefer, with the source shown.
- Large text and a reader for small print, for labels and leaflets.
Emma: a glaucoma companion created by doctors.
Everything stays on your phone. Pay once, keep it for life.
Where this comes from
Every statement on this page comes from public health guidance. We checked each one against the live page of its source on 19 October 2026. Guidance can change, so the live page is always the most current version.
- Glaucoma — NHS. Page last reviewed 13 June 2025.
- Vision loss — NHS. Page last reviewed 28 August 2025.
- Glaucoma — US National Eye Institute.
- Glaucoma medicines — US National Eye Institute. Last updated 5 December 2024.
- Low vision — US National Eye Institute.
- Glaucoma — MedlinePlus (US National Library of Medicine).
- Glaucoma (Papahewa) — Health New Zealand | Te Whatu Ora.