Sunken eyes describe a hollowed, shadowed appearance around the eye sockets where the eyes seem to sit deeper than normal. In most cases, this is a cosmetic concern driven by aging, dehydration, or lack of sleep. But when sunken eyes appear suddenly, affect only one eye, or come with other symptoms, they can signal something that needs medical attention.
What’s Happening Under the Skin
The area around your eyes has some of the thinnest skin on your body, stretched over a layer of fat pads that cushion the eyeball inside the bony socket. When those fat pads shrink, the bone underneath remodels, or the skin loses collagen, the result is a hollow, shadowed look.
Facial fat pads play a critical role in maintaining volume and contour. With aging, these compartments deflate, and the underlying bone gradually loses mineral density. The combination creates a sunken appearance that gets more pronounced over time, typically starting in your 30s or 40s and deepening through later decades. This is the most common explanation for sunken eyes and is entirely normal.
Common, Everyday Causes
Aging accounts for most cases, but several reversible factors can make eyes look hollow well before age plays a role:
- Dehydration. When your body is low on fluids, the thin periorbital skin loses plumpness quickly. Even mild dehydration from illness, exercise, or not drinking enough water can make the hollows more visible.
- Poor sleep. Sleep deprivation dilates blood vessels under the eyes and reduces tissue volume temporarily, deepening shadows.
- Significant weight loss. Losing a large amount of body fat affects the face early, and the fat pads around the eyes are among the first to thin out.
- Nutritional gaps. Iron deficiency lowers hemoglobin levels, reducing the oxygen carried in your blood. The thin skin under the eyes reflects this poorly oxygenated blood as a dusky, bluish-grey tinge. Vitamin K deficiency increases the visibility of blood vessels in the same area, and low vitamin B12 causes pallor that makes dark shadows stand out more. A diet low in vitamins C and E slows collagen maintenance, thinning the periorbital skin over time.
- Alcohol. Regular drinking dehydrates the skin and depletes B vitamins and iron, both of which affect the under-eye area.
Medical Conditions That Cause Sunken Eyes
When hollowness goes beyond normal aging or lifestyle factors, the medical term is enophthalmos. This can be something you’re born with or something that develops later. It can affect one eye or both.
Trauma is one of the most common medical causes. Car accidents, motorcycle crashes, and physical fights can fracture the thin bones surrounding the eye socket. When the orbital floor breaks, the eyeball can settle lower and deeper into the socket, sometimes permanently if not repaired.
Horner’s syndrome, a nerve condition affecting one side of the face, can produce a subtly sunken appearance in the affected eye along with a drooping eyelid and a smaller pupil. This combination of symptoms points to a disruption in the nerve pathway running from the brain to the eye, and it requires investigation because the underlying cause can range from benign to serious.
Certain glaucoma eye drops can also cause a sunken look. Prostaglandin-based drops, a very common class of glaucoma medication, shrink the fat cells around the eye over time. The fat cells don’t die off entirely; they shrink in size, leading to a deepened upper eyelid crease, mild sinking of the eye, and changes in eyelid position. This side effect is common enough that it’s now listed on the packaging. If you use glaucoma drops and notice one eye looking more hollow than the other, that’s likely the cause.
Silent Sinus Syndrome
One particularly sneaky cause is silent sinus syndrome, a condition where a blocked sinus cavity slowly collapses inward over months or years. Your maxillary sinus (the one in your cheek, beside your nose) gets clogged, and the trapped secretions are gradually reabsorbed. This creates a vacuum effect that pulls the sinus walls inward, thinning the bone that forms the floor of your eye socket. As that floor weakens and drops, the eye sinks.
The condition earns its name because the sinus blockage itself often causes no pain or obvious symptoms. You might not have sinus pressure, congestion, or infections. Instead, the first thing you notice is that one eye looks different. A sunken eye appears in almost all cases, with the eye dropping 2 to 6 millimeters deeper than normal. About half of people also experience the eyeball shifting downward. Eyelid drooping occurs in up to 88% of cases, and some people develop blurred vision or what looks like a squint.
When One Eye Looks Different From the Other
Mild asymmetry between your eyes is normal. But a difference of more than 2 millimeters in how far the eyes protrude from the socket is considered abnormal and worth investigating. For reference, normal eye protrusion averages about 16.5 mm in Caucasian men and 15.4 mm in Caucasian women, with higher averages in Black populations and lower averages in Asian populations.
A single sunken eye that develops gradually could point to silent sinus syndrome, a prior facial fracture you didn’t realize was significant, or a condition like neurofibromatosis affecting the bone structure. A single sunken eye that appears suddenly, especially after any kind of facial impact, suggests an orbital fracture. In either scenario, imaging is the next step to figure out what’s going on structurally.
Treating Sunken Eyes
For lifestyle-related hollowing, the fix is often straightforward. Rehydrating, improving sleep, and addressing nutritional deficiencies can make a visible difference. If blood tests confirm low iron or B12, supplementation helps. Vitamin C supports collagen production in the periorbital skin over time.
For age-related volume loss, dermal fillers are the most popular cosmetic option. Two hyaluronic acid fillers are currently FDA-approved specifically for under-eye hollows: Juvéderm Volbella XC and Restylane Eyelight. Restylane Eyelight lasts up to 18 months. These fillers work by replacing lost volume directly in the tear trough, the groove that runs from the inner corner of the eye down along the cheek.
For more significant or structural sunken eyes, surgery is an option. Lower eyelid blepharoplasty with fat repositioning involves moving the eye’s own fat pads from where they’ve bulged or shifted into the hollow areas where volume has been lost. The surgeon releases the fat pockets and sutures them into a new position along the tear trough. When the cause is an orbital fracture or silent sinus syndrome, the goal shifts to repairing the bone floor of the socket, sometimes with an implant to restore the eye to its normal position.
If glaucoma drops are the cause, switching to a non-prostaglandin medication often allows the fat to partially recover over several months, though the reversal isn’t always complete.