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Medically reviewed and verified by Kate Burke, MD, MHA
For people living with diabetes, there are a number of potential complications to watch out for! One area of the body that diabetes can impact is the eyes. Your eyes have a number of tiny blood vessels running through them, and high blood sugar levels can damage these vessels over time. Both glaucoma and diabetic macular edema (DME) are two serious eye conditions that can lead to vision loss if not properly managed. While they are distinct diseases, they share a connection through diabetes and its impact on the eyes. If you have diabetes you are at risk of getting either condition! Understanding these diseases can help with early detection and better management.
What Is Glaucoma?
Glaucoma is a group of eye diseases that damage the optic nerve. The optic nerve itself carries information from the back of the eye to the brain. When it is damaged, your eye can no longer transmit information! The more damage, the worse your vision gets. Glaucoma is one of the leading causes of blindness worldwide. Experts estimate that while over 4 million Americans have the condition, less than half are aware of it.
How Does Glaucoma Develop?
There are a number of reasons someone can get glaucoma! There is currently one known modifiable risk factor - eye pressure. The eye constantly makes a fluid called aqueous humor. This fluid is supposed to drain out of the eye through an area called the drainage angle. When the drainage angle does not work properly or is obstructed, the fluid builds up. This leads to increased intraocular pressure. Over time, this pressure damages the optic nerve.
The optic nerve is made up of over a million tiny fibers, and as these fibers die, blind spots start to pop up in your vision. One of the dangers of glaucoma is that many people are unaware they have the condition when it starts. By the time symptoms become more noticeable, there can already be significant damage done to the optic nerve. People with diabetes are twice as likely to get glaucoma than those without!
Types of Glaucoma
Primary Open-Angle Glaucoma (POAG)
Primary open-angle glaucoma(PAOG)is the most common type of glaucoma, accounting for over 90% of the cases in the United States. It occurs when the trabecular meshwork, the eye’s drainage system, gradually becomes less efficient, leading to increased resistance to aqueous humor outflow. As a result, eye pressure slowly rises, which can damage the optic nerve over time. Because this form develops gradually and is often symptom-free in its early stages, many people do not notice vision loss until significant damage has occurred. Treatment focuses on lowering IOP using medications, laser therapy or surgery (e.g., trabeculectomy).
Normal-Tension Glaucoma (NTG)
Normal-tension glaucoma is a form of open-angle glaucoma that occurs in people with normal Intraocular Pressure(IOP). The pathophysiology of NTG is multifactorial and not completely understood. Treatment aims to lower IOP further using medications, laser therapy, or surgery, and may also involve addressing vascular risk factors.
Primary Angle-Closure Glaucoma (PACG)
While primary open-angle glaucoma is slow developing and often unnoticed, acute primary angle-closure glaucoma is a medical emergency and needs immediate treatment. Here, an anatomically narrow anterior chamber angle leads to obstruction of aqueous outflow and a spike in the intraoccular pressure(IOP). People often experience intense pain in their eye, nausea and blurry vision. A study by Li et al. found that the rate of blindness after Acute PACG was significantly associated with the time from symptom onset to treatment (TST). The critical time window associated with a blindness rate of ≤1% was identified as 4.6 hours. Acute PACG is a medical emergency requiring rapid IOP reduction with medications and laser iridotomy.
Developmental Glaucomas
These are congenital or juvenile glaucomas resulting from developmental anomalies of the anterior chamber angle. Diagnosis is based on clinical examination and imaging, and treatment often involves surgical intervention.
Glaucoma vs. DME
Diabetes affects both blood vessels and nerve tissues throughout the body, including the eyes. People with diabetes have a higher risk of getting glaucoma because of changes in eye pressure, damage to nerves, and vascular function. Diabetic macular edema (DME) happens when damaged blood vessels in the retina leak fluid. This causes swelling in the macula, the part of the retina responsible for sharp vision. Both conditions can cause vision loss, but DME comes from fluid leakage in the retina, while glaucoma is caused by progressive optic nerve damage, often due to elevated eye pressure.
Since diabetes increases the risk of both DME and glaucoma, you should take steps to protect your vision and health! The first thing to do is get regular eye exams. Any time you notice changes in your vision, like blurriness or blind spots, be sure to bring them up to your doctor! As both glaucoma and DME can come about as a result of diabetes, managing the underlying condition is also important. Controlling your blood sugar levels reduces the chances blood vessels in your eye will be damaged.
Glaucoma and diabetic macular edema are both serious conditions that can lead to vision loss. While they are different diseases, they are connected through diabetes. Comprehensive regular eye exams including a dilated eye exam, including OCT (optical coherence tomography-retina check) and tonometry (IOP test), are necessary for the accurate diagnosis and effective management of glaucoma and DME. Good blood sugar management and treatment are critical for your overall health and vision as well.
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