Glaucoma, cataract and macular degeneration: know the difference

Blurred vision is a symptom, not a diagnosis. Glaucoma, cataract and macular degeneration affect different parts of the eye, so they do not share one test or one treatment. Some can develop before you notice a change. Understanding the differences helps you ask better questions, whether you are looking after your own eyes or supporting a family member. 1 2 3

First: changes that should not wait

A suddenly painful red eye with blurred vision, especially with nausea, needs emergency assessment now. Acute angle-closure glaucoma is one possible cause. Do not wait for a routine sight test. 1

New wavy or crooked straight lines, a new central blurred patch or a rapid change in central vision needs urgent eye assessment. Wet age-related macular degeneration can damage vision quickly, and prompt treatment matters. Do not assume the change is simply cataract or a new glasses prescription. 3 6

Three conditions, three parts of the eye

Glaucoma damages the optic nerve, which carries visual information from the eye to the brain. Cataract clouds the natural lens inside the eye. Age-related macular degeneration (AMD) affects the macula, the central part of the light-sensitive retina responsible for detailed, straight-ahead vision. 1 2 3

These conditions become more common with age, but not every form is confined to older people: glaucoma and cataract can also affect children. This guide’s macular-degeneration section focuses on AMD, not every disease that can affect the macula. 1 3 9

Glaucoma: protecting the optic nerve

Open-angle glaucoma often causes no obvious symptoms early on. Peripheral vision may be lost gradually, so feeling that your sight is normal does not rule it out. Glaucoma-related nerve damage and lost vision cannot currently be reversed; treatment aims to protect the vision that remains. 1 4

Eye pressure matters, but glaucoma is not simply another name for high pressure. Some people have high pressure without glaucoma; others develop glaucoma while their pressure is within the usual range. A pressure reading alone cannot establish or exclude the diagnosis. 1 4

Assessment looks at the optic nerve as well as pressure. Visual-field testing checks visual function, while optical coherence tomography (OCT) can measure the nerve-fibre and ganglion-cell layers. Examination of the drainage angle helps identify the type of glaucoma. These findings are interpreted together and monitored over time. 4

Treatment lowers eye pressure using drops, laser procedures or surgery, selected according to the type and severity of disease and the person’s needs. Pressure reduction can slow progression even in normal-tension glaucoma. Treatment and follow-up continue even when the eye feels comfortable. Older age and a family history are reasons to discuss your individual risk. 1 4

Cataract: when the lens becomes cloudy

Cataract can cause gradual blur, glare, halos around lights, faded colours and difficulty seeing at night. Early cataract may cause no symptoms. An examination checks the lens and looks for other explanations for reduced vision, including retinal or optic-nerve disease. 2 5

In the early stages, a new glasses prescription, better lighting or magnification may help. Surgery removes the cloudy lens and usually replaces it with an artificial intraocular lens. Glasses can improve focus, but they do not remove the cataract. 2

For adult cataract, the decision about surgery depends on how vision affects daily life and the likely benefits and risks, not just whether a cataract is present. Reading, driving, work and glare can matter even when a chart score looks relatively good. Other eye conditions may limit the expected improvement. 5

A child with a visually significant cataract is different: early treatment can be needed to prevent disruption of visual development and amblyopia. The relaxed timing sometimes appropriate for an adult cataract should not be applied to a child’s cataract. 9

Macular degeneration: central vision and disease stage

AMD mainly affects detailed central vision used for reading and recognising faces. Early AMD may be symptom-free; later changes can include distortion, central blur or a central blank spot. Risk increases with age, and smoking and family history are important risk factors. 3 6

Dry AMD includes early and intermediate stages and a late form called geographic atrophy, in which retinal tissue is lost. Wet, or neovascular, AMD involves abnormal blood vessels and can cause faster loss of vision. A dilated retinal examination and OCT help identify the type and guide treatment. 3 6

Wet AMD is generally treated first with injections of anti-VEGF medicines into the eye. These treatments aim to control abnormal blood-vessel activity and preserve or improve vision. They usually require a course of treatment and monitoring rather than a single permanent fix. 6

AREDS2 vitamin and mineral supplements are for specific AMD stages, commonly intermediate AMD or certain people with advanced AMD in one eye. They are not a general eye-health supplement for everyone, do not prevent AMD in healthy eyes and do not replace treatment for wet AMD. The original AREDS formula contains beta-carotene, which increases lung-cancer risk in people who smoke or used to smoke; AREDS2 uses lutein and zeaxanthin instead. The stage and formula should be checked before starting supplements. 6 7

It is no longer accurate to say that every form of late dry AMD has no treatment. In the United States, the complement inhibitor avacincaptad pegol is approved for geographic atrophy secondary to AMD. Trials showed slower growth of the atrophic area, not restoration of lost retinal tissue. Injections carry risks, including eye infection, retinal detachment and increased risk of wet AMD. Whether such treatment is suitable, licensed and available locally is a separate decision. 8

What to ask at an eye examination

Ask which part of the eye is affected, which tests support the diagnosis and whether more than one condition is contributing. For glaucoma, ask about the target pressure and how progression will be checked. For cataract, discuss the activities you want to improve and what other eye disease might limit the result. For AMD, ask for the type and stage before discussing injections or supplements. 4 5 6

The key difference is the treatment goal: glaucoma care protects remaining nerve function; cataract surgery removes a cloudy lens; AMD care depends on the type and stage of retinal disease. New symptoms should trigger a fresh assessment rather than being automatically blamed on an existing diagnosis. 1 2 3 4 5 6

Sources

[1] Glaucoma. National Eye Institute, updated August 2026.

[2] Cataracts. National Eye Institute, updated August 2026.

[3] Age-related macular degeneration. National Eye Institute, 2021; used for anatomy and symptoms, not current treatment availability.

[4] Primary Open-Angle Glaucoma Preferred Practice Pattern. American Academy of Ophthalmology, 2026 release, approved September 2025.

[5] Cataract/Anterior Segment Summary Benchmark. American Academy of Ophthalmology, 2025.

[6] Age-Related Macular Degeneration Preferred Practice Pattern. American Academy of Ophthalmology / Ophthalmology, 2025.

[7] AREDS 2 supplements for AMD. National Eye Institute, accessed 12 November 2026.

[8] IZERVAY prescribing information. U.S. Food and Drug Administration, 2026 label.

[9] Types of cataract: pediatric cataracts. National Eye Institute, accessed 12 November 2026.