In fact, experts say that one ocular condition comes with distinct signs that you may not realize are major red flags. Read on to learn which symptom in your eyes could signal a major medical emergency—and why it’s best to head to the emergency room for help if you notice them. READ THIS NEXT: If You See Eye Floaters, It Could Be a Sign of This Chronic Condition. While we don’t typically think of ocular conditions as medical emergencies, experts say that acute angle-closure glaucoma (AACG)—sometimes simply called acute glaucoma—is one such condition that requires immediate intervention.ae0fcc31ae342fd3a1346ebb1f342fcb According to the Mayo Clinic, this occurs when “the iris bulges forward to narrow or block the drainage angle formed by the cornea and iris. As a result, fluid [known as aqueous humour] can’t circulate through the eye and pressure increases,” their experts explain. While for some people, angle-closure glaucoma is a chronic condition which develops over time, acute cases come with sudden onset symptoms and warrant a 911 call. “All ocular emergencies, including a penetrating globe injury, retinal detachment, central retinal artery occlusion, acute angle-closure glaucoma, and chemical burns, should be referred immediately to the emergency department or an ophthalmologist,” says the American Academy of Family Physicians. Since AACG affects vision and can trigger a range of other serious symptoms, you should not attempt to drive yourself to the hospital if you experience symptoms. READ THIS NEXT: If You Notice This With Your Eyes, Get Your Thyroid Checked, Doctors Say. During an acute attack of angle-closure glaucoma, the pupils dilate, leading to increased contact between the eye’s iris and lens. This causes what’s known as a pupillary block. “The increasing pupillary block leads to bulging of the iris, acutely closing the angle between the iris and cornea, thus obstructing the aqueous humor outflow tract,” explains a 2022 study published by StatPearls. As fluid pressure builds, symptoms can develop quickly. If this happens, you may notice bulging in the iris, or several other eye symptoms. “Acute angle-closure glaucoma presents as a sudden onset of severe unilateral eye pain or a headache associated with blurred vision, rainbow-colored halos around bright lights, nausea, and vomiting,” the researchers say. While anyone can develop acute angle-closure glaucoma, some people are significantly more likely to be affected than others—and those over age 60 are at highest risk. “This is felt to be due to the increasing size of the lens with age,” explains the StatPearls study. Your gender also influences your odds of a problem: “There is a four-to-one ratio of the incidence of angle-closure glaucoma in women versus men,” the researchers warn. Race, too, plays a role. Acute glaucoma is most common in people of Southeast Asian, Chinese, and Eskimo descent, and least common in black populations. Your family history can make you more susceptible by passing on anatomic features associated with the disease. For more health news sent directly to your inbox, sign up for our daily newsletter. Leaving acute glaucoma untreated—even for a short time—can lead to several serious complications. If not treated in its first stages, it can lead to temporary or permanent blindness. Often, patients will lose their peripheral vision first, later losing their central vision. Experts also warn that if acute glaucoma develops in one eye, the unaffected eye has up to an 80 percent likelihood of developing an acute attack within five to 10 years. This is because it shares the same anatomical features that rendered the first eye vulnerable to the condition. If you experience concerning vision-related symptoms, speak with your doctor to discuss the full range of treatment options available to you—and be sure to make a plan to care for both eyes, even if only one is affected. READ THIS NEXT: If You Notice This Around Your Eyes, Get Your Liver Checked.