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The difference between glaucoma vs. cataracts

side by side illustrated comparison of an eye with glaucoma vs cataract

From the time we wake up to the moment we drift off to sleep, our eyes constantly take in information. Like the rest of our body, our eyes eventually tire, age, and become susceptible to disease and other vision-related conditions.

Glaucoma vs cataracts, what's the difference?

Two of the most common vision-threatening conditions are glaucoma and cataracts. While many are aware of these conditions exist, few people understand how they affect eyesight or how they differ.

To bring some clarity to the subject, we explain the basics of cataracts and glaucoma, and describe the differences, similarities and threats they pose to your vision if left untreated. 

What is glaucoma?

Glaucoma is a condition caused by excessive pressure in the eyes. 

Imagine your eyeball as a tiny beach ball. If you add too much air to the beach ball, the pressure puts it at a higher risk of popping. While glaucoma will not cause your eyeball to pop, having too much pressure in the eye can impact and even damage the optic nerve.

The optic nerve sits at the back of the eye and works by transferring visual information from the retina to the part of the brain that processes visual images. When eye pressure gets too high, it begins to press on the optic nerve, making it harder for the optic nerve to do its job. 

The first noticeable symptom of glaucoma is darkening peripheral vision. The longer the condition goes undetected and untreated, the more damage it can do, eventually spreading across your entire field of vision and causing blindness.

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What are cataracts?

Cataracts are characterized by a clouding of the eye’s lens.

The lens of the eye works in several ways that make vision possible. First, the lens focuses light onto the retina so it can create a clear picture to send to the brain using the optic nerve. The lens also allows the eye to change focus, which makes it possible to see distant and up-close objects.

Our eyes’ lenses are essentially made of water and strategically placed protein that allow light to filter through. As we get older, that protein starts to gather into little clumps — cataracts — that cloud the lens.

If left unaddressed, cataracts will continue to worsen, building into a larger, thicker cloud and eventually leading to permanent vision loss.

What are the similarities of glaucoma vs. cataracts?

On the surface, glaucoma and cataracts seem similar: They both occur in older adults, they both affect the eyes and they can both cause vision loss. However, the similarities pretty much end there.

It’s true that both conditions are a natural part of the aging process, and that they're more prevalent in people who have diabetes. But the ways in which they affect the eyes are far from similar.

Glaucoma and cataracts can also both be treated surgically, but the procedures involved are on opposite ends of the eye surgery spectrum.

What are the differences of glaucoma vs. cataracts?

While both glaucoma and cataracts affect vision and can eventually lead to blindness, they are far from being the same. Here are a few of the main differences between the two conditions:


  • No symptoms experienced until vision loss occurs.

  • Condition progresses rapidly once vision loss begins.

  • Eye pressure and optic nerve are affected, causing vision loss.

  • Damage/loss to vision is permanent and cannot be restored.

  • There is a sense of urgency regarding treatment. 


  • Early symptoms consist of blurred or hazy vision and excessive glare.

  • Condition progresses relatively slowly.

  • Eyes’ lenses are affected, causing loss of vision.

  • Cataract surgery can restore lost vision. 

  • While treatment will improve sight, immediate attention isn’t required.

Another difference is how surgical procedures are performed to treat the conditions. Cataract surgery breaks up the cloud of protein and inserts an artificial lens. Glaucoma surgery creates or unblocks the eye's drainage canals, allowing fluid to drain from the eyes and relieving eye pressure.

Glaucoma and cataracts may be two of the most common eye conditions seen in older adults, but that does not mean you should take them lightly. Because glaucoma does not show symptoms until the condition has progressed, it’s important to have regular eye exams so your eye doctor can check your eye pressure and look for early signs of the disease.

Cataracts, while curable with surgery, can still cause you to have poor or lost vision, which is both inconvenient and frightening. Having cataracts diagnosed and treated early will ensure that your vision, even as it changes with age, remains clear and healthy.

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