How Diabetes Affects Your Eyes: Eye Pressure, Glaucoma, and Macular Edema + A Practical Diet Guide

If You Have Diabetes, Are You Worried About Losing Your Vision?

For many people living with diabetes, one of the biggest fears is losing their eyesight.
High blood sugar doesn’t just affect the heart, kidneys, or nerves – it can also silently damage the eyes.

Two things in particular deserve attention:

High eye pressure that can lead to glaucoma and optic nerve damage
Damage to the blood vessels in the macula (the center of your vision), leading to macular edema and vision loss

In this guide, we’ll walk through:

What people with diabetes should know about eye pressure and glaucoma
Why you cannot reliably self-check eye pressure at home
The difference between eye pressure, macular degeneration, and diabetic eye disease
A real-life example of a 78-year-old woman with diabetes
How cruciferous vegetables like cabbage and kale (and a compound called sulforaphane) may support eye health
A three-pillar strategy: medical treatment, regular check-ups, and realistic diet/lifestyle changes

Important: This article is for educational purposes only and does not replace medical advice.
Always talk to your eye doctor or healthcare provider about your personal situation.

A cross-sectional illustration of the eyeball showing how intraocular pressure is generated.

1. What Is Eye Pressure (Intraocular Pressure, IOP)?

1) Eye pressure in simple terms

Eye pressure, or intraocular pressure (IOP), is the pressure inside your eyeball.

Inside the eye:

The front part (behind the cornea and pupil) is filled with a clear fluid called aqueous humor.
The back part is filled with a gel-like substance called vitreous humor.

Your eye constantly produces aqueous humor and also drains it out through a tiny drainage system (the trabecular meshwork and Schlemm’s canal).

For healthy eye pressure:

The amount of fluid produced
And the amount of fluid drained

must stay in balance.

Most people have an IOP in the range of about 10–20 mmHg.
This pressure helps:

Maintain the shape of the eye
Protect delicate structures like the retina and optic nerve

So in short:

Eye pressure = internal fluid pressure created as aqueous humor is produced and drained from the eye.

2) Why is eye pressure so important?

Eye pressure is necessary to maintain eye shape and structure, but:

If it gets too high, it can press on the optic nerve
Over time, this can damage the optic nerve and lead to glaucoma

On the other hand, if eye pressure is too low, that’s also not good for the eye.

That’s why eye pressure is one of the most important numbers your eye doctor checks at every visit.

Summary: You need a certain amount of eye pressure, but if it’s too high for too long, your risk of optic nerve damage and glaucoma increases.

2. Why Eye Pressure Rises – and Why You Can’t Self-Diagnose

Eye pressure mainly depends on:

How much aqueous humor your eye produces
How well it can drain out

If too much fluid is produced, or if the drainage system gets blocked or narrowed, fluid builds up inside the eye and the pressure rises.

1) Common causes of high eye pressure

Primary open-angle glaucoma (the most common chronic form)
- The drainage system becomes less efficient over time
- Eye pressure is slightly elevated for years, often without symptoms
Angle-closure (narrow-angle) glaucoma
- The angle where fluid drains suddenly becomes blocked
- Eye pressure can spike very quickly
- May cause severe pain, headache, and even nausea/vomiting
Steroid use
- Long-term use of steroid eye drops, oral steroids, or inhaled steroids
- Some people are “steroid responders” and develop elevated eye pressure
Eye inflammation, trauma, or tumors
- These can change the internal structure of the eye, affecting fluid outflow
Congenital structural problems
- Some people are born with drainage systems that don’t work properly

In general, diabetes by itself is not considered the main direct cause of high eye pressure.
However, diabetes can make the eye and its blood vessels more fragile, which can complicate things.

2) There Is No Reliable At-Home Eye Pressure Test

At the moment, there is no reliable way to measure eye pressure at home without proper equipment and training.

Symptoms like pain or blurry vision usually appear only after significant damage has already occurred. That’s why relying on symptoms alone is risky.

That said, you should pay attention to warning signs like:

Sudden, severe eye pain or a deep aching feeling in the eye
Headache, nausea, or vomiting
Seeing halos or rainbow-colored rings around lights
Feeling like part of your vision is blurry, dim, or missing

If you notice any of these, you should see an eye doctor or go to the emergency room immediately.

Summary: There is no trustworthy “self-check list” for eye pressure.
The safest approach is regular eye exams with eye pressure measurements.

Comparison image showing normal vision versus vision loss caused by glaucoma.

3. High Eye Pressure and Glaucoma: What’s the Connection?

1) What is glaucoma?

Glaucoma is a group of eye diseases where the optic nerve (the “cable” connecting your eye to your brain) gradually gets damaged.

Light enters the eye and is converted into electrical signals
The optic nerve sends those signals to the brain
When the optic nerve is damaged, the brain receives less information

Over time:

Your visual field (the area you can see) slowly narrows
Most people don’t notice this at first
Pain is usually absent in the most common form (open-angle glaucoma)

That’s why glaucoma is often called the “silent thief of sight.”

2) Why does glaucoma happen?

Key risk factors for glaucoma include:

High eye pressure
- One of the strongest risk factors
- Long-term pressure can compress and damage the optic nerve
Age
- Risk increases after age 40
- Especially higher after age 60
Family history
- If your parents or siblings have glaucoma, your risk is higher
Nearsightedness (myopia), especially high myopia
Diabetes, high blood pressure, blood flow problems
- Poor vascular health can make the optic nerve more vulnerable

So, glaucoma is not just a pressure problem.

It’s more like a combination of pressure + blood flow + nerve health + age + genetics.

3) What does glaucoma feel like?

There are two main patterns:

Chronic open-angle glaucoma (most common)
- Eye pressure is slightly elevated over many years
- Usually no pain
- Visual field loss is very slow and subtle
- Both eyes can compensate for each other, so you may not notice until it’s advanced
Acute angle-closure glaucoma
- Eye pressure suddenly rises dramatically
- Severe eye pain, headache, or brow pain
- Nausea and vomiting may occur
- Sudden blurred vision, halos around lights
- This is an emergency and requires immediate treatment

4) How is glaucoma treated?

The main goal of glaucoma treatment is to protect the optic nerve by lowering eye pressure and slowing damage.

Once optic nerve fibers are lost, we currently cannot restore them. So early detection and prevention are critical.

Typical treatments:

Eye drops (medications)
- The most common first-line treatment
- Lower eye pressure by reducing fluid production or improving drainage
- Often used once or twice a day
Laser procedures
- Can improve drainage or reduce fluid production
- Often used when drops aren’t enough or as an additional treatment
Surgery
- Considered when eye drops and lasers are not controlling eye pressure well
- Creates a new drainage pathway or uses small implants to improve outflow

Stopping drops on your own or skipping appointments can allow glaucoma to quietly worsen.
One day you may suddenly realize a large part of your vision is gone — and that loss is usually permanent.

Summary: High eye pressure often doesn’t cause symptoms at first.
Glaucoma can slowly steal your vision, so regular eye exams and consistent treatment are essential.

4. Does Eye Pressure Cause Macular Degeneration?

1) What we know so far

Eye pressure is not considered a main direct cause of age-related macular degeneration (AMD).

Eye pressure is more closely linked to glaucoma and optic nerve damage
Age-related macular degeneration mostly involves the central retina (macula) and its cells and blood vessels

However:

Very high eye pressure can worsen blood flow and metabolism in the eye as a whole
In that sense, it may contribute indirectly to an unhealthy environment in the eye

Still, we don’t explain macular degeneration the same way we explain glaucoma.

In short: high eye pressure → mainly associated with glaucoma and optic nerve damage
Macular degeneration → more associated with age, genetics, blood vessels, and lifestyle factors

2) Major risk factors for age-related macular degeneration (AMD)

When people say “macular degeneration,” they usually mean age-related macular degeneration (AMD).

Big risk factors include:

Age (the most powerful factor)
Genetics / family history
Smoking
Chronic exposure to strong light / UV without protection
Unhealthy diet, obesity, cardiovascular disease
High blood pressure, high cholesterol, vascular problems

So AMD is heavily influenced by age + genetics + blood vessels + lifestyle.

3) “Isn’t diabetes a main cause of macular problems?”

Here’s where things get confusing:

We need to separate:

Age-related macular degeneration (AMD)
- Mainly age, genetics, smoking, diet, and vascular health
Diabetic retinopathy and diabetic macular edema
- Directly caused by long-term high blood sugar
- Damages the tiny blood vessels in the retina and macula

Both can involve the macula, but:

The mechanisms are different
They’re categorized as different diseases

Diabetes can:

Damage small retinal blood vessels
Cause them to leak or become blocked
Lead to diabetic macular edema (fluid in the macula)
Reduce the function of the central retina

So:

Diabetes is not the main classic cause of age-related macular degeneration,
but it does cause its own set of macular problems, such as diabetic macular edema.

Q&A Recap

Q1. Does high eye pressure cause macular degeneration?
→ Not as a major direct cause.
High eye pressure is more strongly linked to glaucoma and optic nerve damage.
Age-related macular degeneration is more about age, genetics, smoking, and vascular health.

Q2. Isn’t diabetes a major cause of macular disease?
→ Diabetes doesn’t directly “cause” classic age-related macular degeneration.
Instead, it causes diabetic retinopathy and diabetic macular edema, which are different but also affect the macula.

5. Diabetes, Eye Pressure, and Glaucoma – Plus a Real-Life Case

If you have diabetes, several things tend to happen over time:

Blood vessels throughout the body, including in the eye, become more fragile
Inflammation and oxidative stress increase
Retinal cells and the optic nerve may become more vulnerable

If you also have:

High eye pressure
Or a natural tendency toward glaucoma

then diabetes can create an environment where glaucoma progresses faster and more severely.

That’s why for people with diabetes, regular monitoring of eye pressure, visual fields, and the optic nerve (OCT) is especially important.

A real-life example: when eye pressure management fails

Here is a real-world case that shows what can happen if eye pressure and eye disease are not handled in time:

A 78-year-old woman who has lived with type 2 diabetes for about 20 years
One day, she developed intense, almost “bursting” pain in one eye
At a local clinic, she was told her eye pressure was very high; she was given medication and a lutein supplement
Her condition didn’t improve, so she was transferred to a university hospital and underwent surgery
One eye eventually lost vision completely
In the other eye, she developed macular problems and now struggles with daily activities

This case illustrates how serious eye complications in people with diabetes can become if treatment is delayed.

Summary: If you have diabetes, you must think in terms of three together:
blood sugar + eye pressure + retinal/optic nerve health.
Especially when eye pressure is high, prompt medical attention is crucial.

Pre-meal cabbage salad with kale, bok choy, raw radish, and a spoonful of olive oil.

6. How Diet Can Support Eye Health: Cabbage, Cruciferous Vegetables, and Sulforaphane

Most people know cabbage as a “stomach-friendly” vegetable.
But it can also be a valuable part of an eye-friendly diet, especially for people with diabetes.

At the center of this is a compound called sulforaphane.

1) What is sulforaphane?

Sulforaphane is a compound derived from glucosinolates found in cruciferous vegetables such as:

Cabbage
Broccoli
Kale
Bok choy
Radish
Cauliflower

When these vegetables are chopped or chewed, an enzyme called myrosinase helps convert glucosinolates into active sulforaphane.

Sulforaphane has strong antioxidant and anti-inflammatory properties and may help protect cells in many organs.

2) How might sulforaphane help with eye pressure and glaucoma?

Current research suggests sulforaphane may:

Reduce oxidative stress
- High eye pressure and glaucoma are associated with oxidative stress in the optic nerve and retina
- Sulforaphane can boost the body’s own antioxidant defense systems
Help control inflammation
- Elevated eye pressure can trigger inflammation around the optic nerve and retina
- Sulforaphane can help down-regulate inflammatory pathways
Support cell survival
- It may help retinal cells and optic nerve fibers cope better with stress
- Potentially slowing the rate of damage as an adjunctive (supportive) strategy

Note: Sulforaphane is not a cure for glaucoma or high eye pressure.
It’s better to think of it as a supportive nutrient that may help protect the eye environment alongside proper medical treatment.

3) How might sulforaphane support macular and retinal health?

Sulforaphane may also:

Support retinal blood vessels
- The cells in the macula are very sensitive to blood flow and oxidative stress
- Sulforaphane’s antioxidant effects may help protect tiny blood vessels in the retina
Play a supportive role in diabetic retinopathy
- In diabetes, high blood sugar can damage the inner lining of blood vessels
- This can lead to leakage and macular edema
- By supporting endothelial cells and reducing inflammation, sulforaphane may help as a supportive factor
  (again, not a stand-alone treatment)

Summary: Sulforaphane may act as a “supporting actor” that helps protect the retina, macula, and optic nerve in stressful conditions — such as diabetes, high eye pressure, and inflammation.

4) Why eat cabbage before meals?

Eating cabbage and other vegetables before your main meal may:

Help slow down the rise in blood sugar after eating
Improve overall blood sugar control over time
Support healthier blood vessels and less inflammation in the eye

When eaten raw or lightly cooked, cabbage can provide more of the sensitive enzymes and compounds needed for sulforaphane production.

To boost sulforaphane activation:

Eat cabbage raw or lightly steamed
Combine it with other cruciferous vegetables that are rich in myrosinase, such as:
- Kale
- Bok choy
- Raw radish

Tip: A simple “pre-meal cabbage salad” with other cruciferous veggies and a small amount of healthy oil can be a practical daily habit for people with diabetes who are concerned about eye health.

7. A Practical Pre-Meal Cabbage Combo for People With Diabetes

1) Sulforaphane and myrosinase: the teamwork

If you cook cabbage for too long or at very high heat, some of the enzymes needed to create sulforaphane may be reduced.

But there’s an easy workaround:

Combine cabbage (the sulforaphane precursor source)
With other cruciferous vegetables rich in myrosinase

This way, even if some enzyme activity in the cabbage is reduced, other vegetables can help.

2) Vegetables rich in myrosinase

Myrosinase is found widely in cruciferous vegetables, for example:

Broccoli sprouts
Mustard greens and mustard seeds
Kale
Bok choy
Raw radish
Cabbage, cauliflower, and others

3) How to build an eye-friendly pre-meal salad

Think in terms of a simple routine:

“Before my main meal, I have a small bowl of cabbage-based salad.”

For example:

Base: cabbage
- Finely shred raw cabbage
- Or lightly steam/quickly blanch it (don’t overcook)
Add myrosinase boosters: kale / bok choy / raw radish
- Add a few raw kale leaves, chopped small
- Slice bok choy thinly (raw or lightly steamed)
- Add a spoonful of thinly sliced raw radish
This gives you a mix like:

“Cabbage (sulforaphane source) + kale/bok choy/radish (myrosinase source)”
Add a bit of healthy fat
- Drizzle 1 teaspoon of extra-virgin olive oil
- Or use a small amount of perilla oil (a nutty-tasting seed oil popular in Korean cuisine, rich in omega-3)
- Go very easy on salt
- Avoid sugary dressings and syrups, especially with diabetes

This kind of salad:

Supports antioxidant and anti-inflammatory pathways
May gently help with blood sugar control
Fits naturally into a daily meal routine

Note: If you have digestive issues, allergies, or are on special medication, check with your doctor or dietitian before making big dietary changes.

8. How Diet Helps With Eye Pressure, Blood Vessels, and Blood Sugar

1) Better blood sugar control

Eating non-starchy vegetables before a meal can:

Slow digestion
Reduce blood sugar spikes after eating

For people with diabetes, this can help reduce long-term damage to small vessels in the retina and the optic nerve.

2) Better vascular and inflammation status

Combining:

Cruciferous vegetables (sulforaphane)
Healthy fats like olive oil or perilla oil

may help:

Reduce systemic inflammation
Support healthier blood vessels throughout the body, including the eye

Over time, this might contribute to:

A lower risk of diabetic retinopathy
Slower progression of macular edema
A more favorable environment for glaucoma management

3) Weight and metabolic health

Starting your meal with vegetables:

Helps you feel full sooner
Can make it easier to control portion sizes
Supports weight and metabolic health

If obesity and metabolic syndrome improve, it can positively affect:

Blood sugar
Blood pressure
Possibly eye pressure and overall eye health as well

Important: Diet cannot replace medical treatment for eye pressure, glaucoma, or diabetic retinopathy.
Think of it as “cleaning up the internal environment” so that your treatments can work more effectively.

9. A Three-Pillar Strategy to Protect Your Eyes When You Have Diabetes

You can think of eye protection in diabetes as a three-pillar system:

Pillar	Focus	Goal
1. Medical treatment	Eye drops, laser, surgery	Reach target eye pressure and protect the optic nerve
2. Regular check-ups	Eye pressure, visual field tests, OCT	Detect problems early and track progression
3. Diet & lifestyle	Pre-meal cruciferous veggies, healthy fats, no smoking, blood pressure and blood sugar management	Support vascular health and slow damage to retina and optic nerve

Eye pressure and eye disease are best managed when you combine all three:

Follow your doctor’s treatment plan (medications, laser, or surgery if needed)
Never skip regular eye examinations
Build realistic, sustainable diet and lifestyle habits, such as:
- Pre-meal cabbage and cruciferous vegetables
- Healthy oils like olive oil
- Blood sugar, blood pressure, and weight control
- Not smoking

Summary:
If you live with diabetes, protect your sight by combining:
(1) regular eye exams, (2) proper treatment, and (3) an eye- and vessel-friendly diet.
Small daily habits can make a big difference over the long term.

Age-Related Macular Degeneration (AMD) Prevention Guide: Lutein, Zeaxanthin (AREDS 2), and the Secret of Complex Nutrients

The Ultimate Superfood Guide for Eye Health: Lutein, Omega-3 & More

Cabbage Superfood: How Vitamin U and Sulforaphane Support Digestion, Blood Sugar, and Cholesterol

References

American Academy of Ophthalmology (AAO). Diabetic Eye Disease; Glaucoma.

National Eye Institute (NEI). Diabetic Retinopathy; Diabetic Macular Edema.
Chung YR et al. Diabetic Retinopathy and Current Treatment Status in Korean Patients with Diabetes Mellitus. Diabetes & Metabolism Journal. 2020.
Kim JH et al. Prevalence and Related Factors of Diabetic Retinopathy in Rural Korean Patients with Type 2 Diabetes. Journal of Korean Medical Science (J Korean Med Sci). 2011.
Harvard T.H. Chan School of Public Health. Nutrition information on cruciferous vegetables and sulforaphane.

※ Some of the images in this article were created using AI image generation tools provided by Miricanvas, ChatGPT, Google Gemini, and Wrtn.

Disclaimer

This article is for information and education only and does not replace professional medical advice, diagnosis, or treatment.
If you have diabetes, glaucoma, macular problems, or any other health condition, please consult your doctor, ophthalmologist, or pharmacist before changing your medications, supplements, or diet.