How Your Eyes Help Us Diagnose Certain Conditions

“Eyes are the windows to the soul.” 

The famous quote by William Shakespeare is a true one indeed. Many psychologists would agree that by a mere glance at someone’s eyes, we can deduce many things. Whether someone’s smile is genuine or simply out of politeness can be easily seen by looking at the lateral crinkle of the eyes we involuntarily make when we smile genuinely. Also, our pupils dilate when we look at something that interests us.

While these psychological phenomena are intriguing, to say the least, are there any more signs that can show us physiological or even pathological processes taking place in our bodies?   

When we talk about the connection between the eyes and the liver or the eyes and the heart, at first glance, it seems to us that there is not much connection between these organs. But when we think a little deeper, certain conditions could indicate their connection, and we could conclude what kind of pathological changes are involved in one organ by observing another.

1) Liver

When we talk about liver conditions, we can say that there are several different signs on the periphery of our body, including our eyes, that can indicate these conditions. The first sign we may notice is jaundice, which is visible as a yellow discoloration of the sclera. 

The cause of jaundice is the accumulation of bilirubin that is not completely broken down in the liver and excreted through the bile. The most common conditions in which this disorder occurs are conditions in which normal liver function is disturbed, such as fibrosis and cirrhosis of the liver, as well as various inflammatory diseases of the liver (hepatitis) and chronic alcoholism.  Jaundice is the most common sign of liver disease, but it is worth mentioning some other signs that are not so common and can serve as a valuable diagnostic tool. 

Another important sign is the appearance of accumulations of lipid deposits on the outside of the upper or lower eyelid - the so-called xanthelasma. Xanthelasma can give us information about several possible conditions, but the most important ones are hypercholesterolemia and hyperlipidemia, which often occur due to disorders of HDL and LDL ("good" and "bad" cholesterol) synthesis or breakdown.

Although xanthelasma does not serve as a tool for a specific diagnosis, we can still narrow down the choice in diagnosing the disease. 

Another significant phenomenon in the human eye that points us to liver disease is the appearance of the so-called greenish Kayser-Fleischer ring around the iris of the eye. Kayser-Fleischer's ring indicates the appearance of Wilson's disease, in which the liver is unable to excrete copper through the bile, so copper accumulates in the tissues of the liver AND the eye. 

2) Heart

Regarding the signs that indicate diseases or disorders of the heart, it is most important to mention some conditions in which it is obvious that there is a pathological change in the physiological state of the ocular blood vessels, and thus the heart. 

The most important condition that can be seen is high blood pressure or hypertension. Hypertension can manifest itself in the form of various symptoms in the eye itself, some of which are vision loss, bleeding, blurred vision, or any other form of unpleasant change that interferes with the normal functioning of vision. 

The cause of such changes is most often retinopathy or damage to the retina due to its improper blood supply. Hypertension can also cause disorders in the proper coagulation of blood, so long-term hypertension can clog the arteries that supply the retina or optic nerve and consequently cause complete loss of vision. Another cause of blockage of the ocular arteries is embolic accumulations, which most often reach the ocular arteries through the carotid artery by separating from the arteriosclerotic plaque in some parts of the artery. 

When talking about the connection between the heart and the eyes, it is also important never to ignore the blue sclera. Blue discoloration of the eye can point to a condition called osteogenesis imperfecta, which is a connective tissue disorder affecting many tissues in our body, including the heart, and can lead to the aforementioned bluish color of the sclera.

3) Endocrine system

Many endocrine disorders, and especially thyroid conditions, can lead to changes in the appearance of our eyes.

Graves' disease, for example, is a condition in which our immune system produces antibodies that stimulate the thyroid gland to produce too many thyroid hormones- a condition named hyperthyroidism.

A classic finding in Graves' disease is exophthalmos or bulging of the eyes.

4) Kidneys

While kidney disease, such as nephrotic syndrome, usually doesn’t cause direct changes in the person’s eyes, it can cause swelling of the eyelids- a good indicator that some kind of fluid retention is happening in the body.

5) Brain

Neurological diseases may be most commonly associated with changes in the function of our eyes, and a core part of neurological exams includes proper assessment of eye function.

Unequal pupils (anisocoria) or drooping eyelids (ptosis) can indicate cranial nerve damage, brain tumors, or stroke.

You might have heard about the FAST protocol used in stroke.

• F = Face Drooping – Does one side of the face droop, or is it numb? Ask the person to smile. Is the person's smile uneven?
• A = Arm Weakness – Is one arm weak or numb? Ask the person to raise both arms. Does one arm drift downward?
• S = Speech Difficulty – Is speech slurred?
• T = Time to call 911 – Stroke is an emergency. Every minute counts. Call 911 immediately. Note the time when any of the symptoms first appear.

Another sign besides those in the FAST protocol that could point us to a stroke is called the pupillary reflex test. The test itself is simple:  you shine light into a person’s eye and watch if the pupils constrict.

In healthy people, pupils constrict due to too much light coming into the eye, much like the aperture of a camera that constricts to limit the light exposure from the outside. If there is an uneven pupillary response, stroke can be suspected, especially if it's accompanied by other signs such as face droop, arm weakness, or speech difficulty.

It is important to mention that an uneven pupillary response doesn’t immediately confirm the diagnosis of a stroke since other neurological conditions can present with the same sign. Conversely, an absence of this sign doesn’t rule out a stroke, and further evaluation and diagnostic methods are needed.

These are just some of the most common and diagnostically valuable signs that tell us about liver, heart disease, and neurological conditions, but there are many more such signs, and they give real diagnostic value only in combination with other diagnostic methods and laboratory findings.

Summary:

The eyes can reveal not only emotional states but also significant physiological and pathological conditions affecting the body.

• Liver Disease
  • Jaundice (yellowing of the sclera) indicates bilirubin buildup due to liver dysfunction (e.g., hepatitis, cirrhosis).
  • Xanthelasma (lipid deposits on eyelids) suggests hyperlipidemia or liver-related cholesterol issues.
  • Kayser-Fleischer rings (greenish rings around the iris) signal Wilson’s disease, where copper accumulates due to liver failure.
• Heart Disease
  • Hypertension can damage retinal blood vessels, leading to vision problems or even blindness.
  • Retinal embolism from atherosclerotic plaques can block ocular arteries.
  • Blue sclera may indicate osteogenesis imperfecta, a connective tissue disorder that can affect the heart.
• Endocrine Disorders
  • Graves' disease (hyperthyroidism) often presents with exophthalmos (bulging eyes).
• Kidney Disease
  • Conditions like nephrotic syndrome can cause eyelid swelling due to fluid retention.
• Neurological Disorders
  • Eye signs like anisocoria (unequal pupils) and ptosis (drooping eyelids) may signal cranial nerve damage, tumors, or stroke.
  • Stroke is often evaluated using the FAST acronym and pupillary light reflex.
    • An uneven pupillary response may suggest stroke, but it isn’t definitive because other neurological conditions can cause the same sign, and its absence doesn't rule out stroke.