Your eyes can reveal surprisingly specific clues about what’s happening elsewhere in your body. Doctors routinely check the eyes for signs of diabetes, high blood pressure, liver disease, anemia, and more. Some of these signs are visible in a mirror, while others require specialized equipment during an eye exam. Here’s what different parts of the eye can tell you about your overall health.
Yellow Eyes Point to Liver Problems
One of the most recognizable eye-health connections is yellowing of the whites of your eyes, known as scleral icterus. This happens when bilirubin, a yellow pigment produced when your body breaks down old red blood cells, builds up in your blood instead of being processed by the liver. Normal bilirubin levels sit below 1 mg/dL, but the yellowing becomes visible once levels exceed 3 mg/dL.
Yellow eyes can signal liver disease, hepatitis, gallstones blocking the bile duct, or conditions that cause excessive red blood cell destruction. The whites of the eyes are often the first place yellowing shows up, sometimes before the skin turns yellow. If you notice a distinctly yellow tint in the mirror, especially one that appeared recently, it warrants prompt medical evaluation.
Pale Inner Eyelids Suggest Anemia
Pulling down your lower eyelid and looking at the tissue underneath is a quick screening technique for anemia that doctors have used for decades. In a healthy person, this tissue (the palpebral conjunctiva) appears pink to red because of the blood vessels beneath it. When hemoglobin is low, the tissue looks pale or washed out.
The accuracy of this check varies depending on how severe the anemia is. Research pooling multiple studies found that conjunctival pallor has a sensitivity ranging from 19% to 97%, with better detection rates for more severe anemia. In one study, the sensitivity jumped to nearly 97% when hemoglobin dropped below 8 g/dL, meaning it catches most cases of significant anemia. For mild anemia, though, it’s far less reliable. Think of this as a useful early signal rather than a definitive test.
A White Ring Around the Iris and Cholesterol
A grayish-white ring that forms around the edge of the iris is called corneal arcus. It’s caused by lipid deposits in the cornea and becomes increasingly common with age. In older adults, it’s often harmless. In people under 50, it’s a different story.
Research on patients with familial hypercholesterolemia found that those with corneal arcus had dramatically higher lifetime cholesterol exposure (an average cholesterol-year score of 11,830 compared to 5,707 in those without the ring) and significantly more calcified plaque in their arteries. The correlation between corneal arcus and arterial calcification was strong (r = 0.67). Based on broader population studies, people under 50 who develop corneal arcus have an increased risk of coronary heart disease and a high probability of some form of high cholesterol. If you’re relatively young and notice a whitish ring forming around your iris, it’s worth getting your lipid levels checked.
What Retinal Exams Reveal About Diabetes
The retina, the light-sensitive tissue lining the back of your eye, is the only place in the body where a doctor can directly observe blood vessels without surgery. This makes a dilated eye exam one of the most powerful tools for catching diabetes-related damage early.
The first clinical sign of diabetic retinopathy is the appearance of microaneurysms, tiny balloon-like bulges in the walls of retinal blood vessels. These develop because chronically high blood sugar weakens the vessel walls. Left unchecked, the damage progresses to bleeding into the retina, fluid leakage that causes swelling in the central vision area, and eventually the growth of fragile new blood vessels that can lead to blindness. Diabetic retinopathy is the most common microvascular complication of diabetes and a leading cause of blindness worldwide, which is why regular dilated eye exams are so important for anyone with diabetes or prediabetes.
How High Blood Pressure Changes Your Eyes
Chronic high blood pressure leaves a distinct trail of damage in the retinal blood vessels that progresses through three phases. First, the small arteries in the retina narrow as they try to compensate for the increased pressure. The normal ratio of artery width to vein width is about 2:3, but in hypertensive retinopathy, this can shrink to as low as 1:3.
If high blood pressure persists, the vessel walls physically thicken and harden. This produces changes that eye doctors describe as “copper wiring” or “silver wiring,” referring to how the arteries reflect light differently because of structural changes in their walls. At points where a hardened artery crosses over a vein, it compresses the vein, creating a visible notch. In the most severe phase, the blood-retinal barrier breaks down entirely, leading to flame-shaped hemorrhages and white patches called cotton wool spots, which indicate areas of the retina that have lost their blood supply. These retinal findings can sometimes reveal undiagnosed hypertension or show that someone’s blood pressure isn’t well controlled.
Dry Eyes and Autoimmune Disease
Persistent, severe dry eyes that don’t respond well to artificial tears can be a sign of Sjögren’s syndrome, an autoimmune condition in which the immune system attacks the glands that produce tears and saliva. The eye surface in Sjögren’s patients shows chronic inflammation, loss of the cells that produce the protective mucus layer of the tear film, and changes to the tiny oil glands in the eyelids that help prevent tears from evaporating too quickly.
Diagnosis typically involves a combination of tests. One simple clinical measure is the Schirmer test, where a small strip of paper is placed under the lower eyelid to measure tear production. A result of 5 mm or less of wetting in five minutes is one of the criteria for Sjögren’s. Other autoimmune conditions, including lupus and rheumatoid arthritis, can also cause eye dryness and inflammation, so persistent dry eyes combined with joint pain, fatigue, or dry mouth are worth mentioning to your doctor.
Copper Rings and Wilson’s Disease
A golden-brown or greenish ring around the edge of the cornea, called a Kayser-Fleischer ring, is one of the hallmark signs of Wilson’s disease, a rare genetic condition in which the body can’t properly eliminate copper. The excess copper deposits in a specific layer of the cornea called Descemet’s membrane. About 95% of Wilson’s disease patients with neurological symptoms have these rings, while roughly 50% of those without neurological involvement show them.
In early stages, the rings usually require a slit-lamp exam to detect, but in severe copper overload, they can be visible to the naked eye. Wilson’s disease is treatable but can be fatal if missed, making this one of the most clinically important things an eye exam can catch.
Unequal Pupil Size
If you notice your pupils are different sizes, the cause is usually benign. About 20% of the population has a slight difference in pupil size (typically less than 0.8 mm) that’s completely normal and has been present since birth. This physiologic difference stays consistent regardless of lighting conditions and doesn’t change suddenly.
New or sudden unequal pupils are a different matter. If the larger pupil is the abnormal one and is accompanied by a drooping eyelid and the eye drifting outward and downward, this can indicate a third nerve palsy, potentially caused by a brain aneurysm that requires emergency imaging. If the smaller pupil is abnormal, with mild drooping and decreased sweating on that side of the face, it may point to Horner syndrome. When Horner syndrome is accompanied by pain, especially neck or head pain, it can indicate a tear in the carotid artery, which is also an emergency. A sudden severe headache, coughing up blood, or sudden vision changes alongside new pupil asymmetry all warrant immediate medical attention.
Yellowish Eyelid Bumps
Soft, yellowish patches or bumps on or around the eyelids are called xanthelasma. They’ve long been assumed to indicate high cholesterol, but the evidence is more nuanced than you might expect. A case-control study comparing patients with xanthelasma to controls found that rates of dyslipidemia were essentially the same between the two groups (42% vs. 46%), as were cardiovascular disease rates (about 9% vs. 10%). Lipid profiles, including total cholesterol, LDL, HDL, and triglycerides, showed no significant differences.
This doesn’t mean you should ignore them entirely. They’re still worth mentioning at a checkup, especially if you haven’t had your cholesterol tested recently. But their presence alone isn’t a reliable indicator of heart disease risk.
What About Iridology?
Iridology, the practice of diagnosing health conditions by examining patterns, colors, and markings in the iris, is not supported by scientific evidence. A systematic review of controlled studies concluded that iridology is not a valid diagnostic method. The legitimate health information your eyes provide comes from specific, well-understood signs like the ones described above, not from reading iris patterns like a map of your organs. If someone offers you an iridology reading, know that it has no diagnostic value.