Name: This Is What Sugar Does to Your Eyes
Uploaded: 2026-02-26T14:15:42.000Z
Duration: 5 min 55 s
Description: Thousands of YouTube videos with English-Chinese subtitles! Now you can learn to understand native speakers, expand your vocabulary, and improve your pronunciation...

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Okay, so we need to talk about how sugar affects the eyes, because I see a lot of doctors here on the Internet talking about sugar and simple carbohydrates and how they not only contribute to obesity and diabetes, but

Adverbs of degree

also to inflammation throughout our bodies, high blood pressure, almost everything.

But I never see anybody talk about how sugar affects the eyes.

If you feel like your vision is becoming blurry or maybe you're seeing new spots in your vision, then it may not just be your eyes changing, it could be your blood Sugar.

I'm a board certified doctor of optometry.

And I'm sharing this information because I don't want anybody to lose their vision or go blind.

Now, in the eye clinic, we see the effects of sugar on the eyes all the time, but

usually in the extreme cases of things like diabetes.

But even for people who are not diabetic, we still often see these, especially for people who maybe don't know that they're diabetic or heading in that direction.

So the first way sugar can affect the eyes, it can cause your vision to go blurry.

Oftentimes, people will notice vision is harder to focus up close or sometimes even see in the distance.

And this is because elevated blood sugar will cause the lens inside the eye to swell.

And with that swelling, you often get a prescription change.

They'll come in because they think their glasses are wrong, but

in reality, they just need to have their blood sugar come down to normal, which sometimes takes up to about three months or so.

Number two is that sugar can cause cataracts for the same reason of that lens swelling inside of the eye.

When the lens swells, the lens proteins change, and you can develop a cataract much faster.

And unfortunately, cataracts not only makes your vision blurry, but it decreases contrast.

It makes it difficult to see at nighttime because there's often a lot of glare.

Now, the next few examples I'm going to share all stem from bleeding that occurs inside of the eye, something that we call retinopathy, which occurs because of fine blood vessels in the back of the eye get damaged with elevated blood sugar, and

So, so number three is when somebody's central vision is blurry or becomes distorted.

And this is in the case of what we call macular edema, where those blood vessels leak fluid and the central part of the retina swells.

And this can cause people's vision to be really blurry.

But you'd be surprised how often People don't have any vision issues yet.

They still are having the swelling going on, which is one of the reasons why, when people are known to have diabetes, it's recommended for them to still see an eye doctor every year, even if they feel like their vision is perfect.

The fourth way sugar can affect the eyes is people can see new spots floating in their vision.

This is usually due to vitreous hemorrhage.

Similarly, when the blood vessels leak inside of the eye, they can bleed and they can float in the gel.

And people will see this as either some blurred vision or kind of new floating spots.

And in more advanced cases of retinopathy, you start to see new blood vessels grow inside the eye, something that we call neovascularization.

You can even see this on number five, which is when you look at somebody's iris, and

you'll see new blood vessels growing on the surface there.

Something that we call rubiosis or iris neovascularization.

Number six is where people can have loss of vision, and

this is sometimes due to more advanced cases of things like diabetic retinopathy, where the blood vessels leak and a fibrous membrane forms, creating a retinal detachment, where this fibrous membrane pulls on the back of the eye and tears part of the retina coming off with it.

And unfortunately, this usually ends up with devastating amounts of vision loss.

Number seven, I don't see many people talk about, and

that's an increased risk of infection or ulcers on the surface surface of the eye or infections of the eyelid.

This occurs because when you have elevated blood sugars, that sugar also ends up in your tear film.

And this is believed to increase the risk of not only ulcers and infections from contact lens wear, but

also things like eyelid styes and blepharitis, which also contributes to number eight, which is an increased risk of meibomian gland dysfunction or dry eye disease, because any amount of inflammation or other types of blepharitis do contribute to damage and breakdown of the oil glands in the eyelids, which destabilizes the tear film, which is then compounded by the ninth way, which is how blood sugars affect your nerves.

And this is significant for the nerves on the surface of the eye, because the nerves on the eye also signal to your brain to make more tears, but

So, in a similar way, how people with diabetes can develop with ulcers on their feet and extremities, you can also end up with ulcers on the eye that don't heal something that we refer to as neurotrophic keratitis.

And then the tenth and final way is double vision.

This is oftentimes seen with people who have either extreme levels of poorly controlled diabetes or kind of just mixed with older age.

There can be ischemic factors that affect the nerves of the muscles of the eye, and

then the muscles don't work together to coordinate the eye directions of where you're gazing, where people may end up seeing.

Constant double vision for a time, which can make it difficult and sometimes scary for eye doctors because, yes, you can have double vision due to ischemic factors, but

you can also have double vision because somebody's having something like a stroke.

So those are not always fun cases to have in the clinic and examine.

Now, the core message of today's video is not to villainize having a sweet treat once in a while, right?

Having a little bit of simple sugar or simple carbohydrates is totally fine in small amounts.

However, if somebody is at risk of something like diabetes or is obese or has other risk factors that may tip them toward having elevated consistently large spikes in blood sugar, then they may have increased risk for vision changes.

And if you're having any of the symptoms that we discussed, of course, don't sit on it.

Now, I tried to make today's video a little bit shorter.

So if you have any questions about anything that you talked about, drop them in the comments section below and I'll try to get back to you.

Or perhaps I'll make another video doing a deeper dive into that subject.

But from here, let me just say thank you so much for watching.