Your eyes are more than just the window to your soul — they also contain telltale signs about your health, from minor conditions to chronic diseases like diabetes and HIV/AIDS.

Every body part has its story, function, and ability to give you signs about things going on in your body. Your eyes are complex organs that are often examined by doctors who are searching for chronic diseases like HIV/AIDS, or even cancer. If you’re curious whether the little details about your eyes are just common features or potential signs of something else, read on.

Bug Eyes

Bulging eyes — or having a “bug-eyed” look — is called exophthalmos. Exophthalmos involves one or both of the eyes bulging out of its “orbit,” similar to a lazy eye, and officially described in Dorland’s Medical Dictionary as an “abnormal protrusion of the eyeball.” This condition is often a sign of Grave’s disease, which involves an overactive thyroid. People with Grave’s disease often experience rapid and irregular pulse, weight loss, and nervousness.

Other diseases that influence the thyroid can often lead to exophthalmos, too, as an overactive thyroid often exhibits symptoms like puffy or swollen eyes as well as bulging eyeballs.

Cloudy Eye or Cataracts

A cataract is the clouding of the lens in the eye affecting vision, and can occur in one or both eyes. It typically happens in older people; according to the National Institutes of Health, more than half of all Americans have had a cataract or cataract surgery by the age of 80. Cataracts, which are clumps of protein that block a small area of the lens, essentially blur vision, making it much more difficult to see shapes and details. Once the clouded area reduces the light that reaches the retina through the lens, your vision will become more blurred and can also be tinted brown. Cataracts are a sign of age, although it's possible for people in their 40's and 50's to develop them and need surgery.

Bloodshot Eyes

We’ve all been there: we drank a little too much the night before, are running low on rest, and look a little disheveled. We’ve got the signature bloodshot eyes too, which is why sunglasses are convenient during such events. In these cases, bloodshot eyes are common and are simply caused when the vessels in the surface of the sclera (white portion) of the eye become swollen — the consequence of hangovers, sun exposure, dry air, dust, allergies, or something simply getting caught in the eye. It could also be a sign of fatigue, stress, or lack of sleep.

Though bloodshot eyes are usually harmless, they can also be signs of something worse. In these cases, the bloodshot look is usually accompanied by other symptoms like itching, pain, or discharge. Bloodshot eyes are typically present in conditions like blepharitis, or swelling of the eyelash along the eyelid, according to the National Institutes of Health. It may also be involved in conditions like corneal ulcers, or uveitis, which is the swelling of the uvea and the iris, ciliary body, and choroid.

Different-Sized Pupils

If you’ve noticed something strange about your pupils — such as the fact that they might be slightly different sizes, with one larger than the other — don’t panic right away, as this is a fairly common condition among people. About 20 percent of the population has anisocoria, or unequal pupils. But it could be a sign of something very serious, such as Horner’s syndrome, which is the combination of drooping eyelids and anisocoria. Horner’s syndrome can be the sign of a tumor in the neck or chest, and should receive medical attention as soon as possible.

HIV/AIDS

One of the remarkable things about our eyes is that they can sometimes show doctors when patients are infected with HIV, or have other chronic diseases like cancer. If not treated properly, HIV/AIDS can lead to serious eye diseases like retinitis — which is the inflammation of the retina, and can lead to blindness. Early symptoms of retinitis include blurred vision, tiny black specks in your line of sight, a blind spot, and flashes of bright lights in your eyes.

Diabetes

Patients with diabetes may also experience eye complications due to the chronic disease. People with diabetes have a higher chance of developing blindness as well as a 40 percent higher risk of getting glaucoma, or a build-up of pressure in the eye that leads to lost vision and nerve damage. Diabetes is also notorious for causes retina problems, or retinopathy, such as nonproliferative retinopathy and proliferative retinopathy. To find out ways to prevent eye diseases from diabetes, read more here.