One eye looks sunken: enophthalmos, and how it differs from hollow eyes

When one eye looks sunken, the question a surgeon asks first is whether the eyeball itself has moved back into the socket or whether the tissue around it has thinned. The first is called enophthalmos, the medical name for an eye set deeper in the orbit, the bony socket that holds the eyeball. The second is hollowing of the lids and cheek. They can look alike in a mirror, they have different causes, and only one of them usually needs a scan.

What is enophthalmos, and how is it different from hollow eyes?

Enophthalmos is a backward shift of the eyeball inside the socket. A review of the condition in Survey of Ophthalmology defines it as posterior displacement of a globe whose size is normal, and says that in one-sided cases a difference of more than 2 mm between the two eyes can be considered diagnostic. Hollowing is a different thing: loss of fat and volume in the lids, the tear trough and the cheek, with the eyeball sitting where it always sat.

Signs of a sunken eyeball often show at the upper lid. The same review lists a deep groove above the eye, called a deep superior sulcus, a narrowed gap between the lids that looks like a droopy lid, and a globe that sits lower than the other, called hypoglobus. Hollowing shows instead as shadow under the eye and a flattened cheek. I cover the lid-cheek groove in my article on tear trough hollowing, and the facial-volume side of the question is written up by a different doctor in The Retreat Clinic's article on hollowing after fast weight loss. This article starts where that one stops: with the position of the eyeball.

Is it really the sunken eye, or the other eye or the lid?

Sometimes the eye that looks sunken is the normal one. The same review describes pseudo-enophthalmos, where an eye appears set back because of a change in lid position, a smaller globe, or a structural difference, with no true shift of the eyeball. A droopy upper lid can make an eye look smaller and deeper. The other eye pushed forward can make the normal one look recessed, which is why thyroid eye disease has to be thought of, as I describe in my article on why one eye looks different in thyroid eye disease.

Ordinary asymmetry is also real. The review notes that globe position varies with age, sex and ethnic background. EyeWiki, the American Academy of Ophthalmology's clinical wiki, quotes a study in which the mean measurement in Asian adults was lower than in Caucasians. A small difference between your eyes is not automatically disease, and the lid and brow explanations are in my article on one eye looking smaller than the other. Old photographs help, because change over time says more than a mirror.

What can make one eyeball sink back into the socket?

The Survey of Ophthalmology review groups the causes by mechanism. The socket can become larger, as after a fracture. The tissue inside it can shrink, as with loss of orbital fat. Or the tissue can contract and pull the eye back, as with scarring or an infiltrating tumour.

An old injury to the socket. The review calls fracture of the orbital floor the most frequent cause. The floor of the socket is thin, and when it breaks, tissue can drop into the sinus below and the socket gains volume. EyeWiki says enophthalmos may be present at the start, but more commonly appears days to weeks afterwards as the swelling settles, and the review adds that it can be missed early and noticed only weeks or months later. I describe the injury itself in my article on orbital fractures after a knock to the eye.

Silent sinus syndrome. An article from the American Academy of Ophthalmology describes it as an acquired condition of adults, with progressive, spontaneous enophthalmos and hypoglobus, caused by poor ventilation of the maxillary sinus, the cheek-bone sinus beside the nose, after its drainage channel blocks. People usually tell the doctor that they had no sinus trouble and no injury. The floor of the socket thins and sinks, and the eye follows it. It tends to present between the third and fifth decades. The review adds that it is very often misdiagnosed and progresses over years without any sign of inflammation.

Fat loss. The review says there is a natural thinning of orbital fat with age, shared with the rest of the face and the temples, and that age-related enophthalmos is symmetrical on both sides and without symptoms. Fat loss can also follow radiotherapy, and scarring after radiotherapy, injury or surgery can pull the eye back. Rare conditions such as scleroderma and hemifacial atrophy can shrink the tissues of the socket. Weight loss is not on that review's list of causes. I would not tell anyone that weight loss cannot affect the look of the eye, because it can change the face. I would say that one eye set back in the socket is not explained by weight loss alone, and deserves a look.

Can one sunken eye be a sign of cancer?

It can be, though it is not the usual cause, and it is better to say so calmly than to leave it out. Some cancers that have spread to the socket make scar-like tissue that pulls the eye backward. The review states that breast cancer spread should be considered in the early thinking about a woman of appropriate age with enophthalmos and no injury, that the sunken eye can be the first sign of the cancer, and that other cancers, including stomach, lung and prostate, have been reported to cause it.

EyeWiki says about 10 per cent of breast cancers that spread to the orbit present with enophthalmos, and that in up to 26 per cent of cases the orbital finding comes before the original tumour is found. The picture described is a slow onset, mild or absent signs of inflammation, eye movements that become restricted, and often double vision, with vision itself unchanged. Nothing in that proves a sunken eye is cancer. Trauma is the main cause of acquired enophthalmos. The point is that a slowly progressive, injury-free change, especially with restricted movement, needs a proper work-up and not reassurance.

How does an oculoplastic surgeon assess a sunken eye?

With measurement, a motility check and imaging.

The measurement is Hertel exophthalmometry. According to EyeWiki, the instrument measures the distance from the outer rim of the socket to the front surface of the cornea, and a difference of more than 2 mm between the eyes warrants further evaluation. The same page is candid about its limits: accuracy and reproducibility vary between examiners, and a fractured rim makes the reading unreliable.

The surgeon also looks at lid position, checks how far the eye moves in every direction and asks about double vision, because restricted movement changes the diagnosis. A CT scan of the orbit, thin-slice with coronal reconstruction, is the standard for a suspected fracture, according to EyeWiki. For the silent sinus picture, the American Academy of Ophthalmology article describes thinning and retraction of the orbital floor and a small, clouded maxillary sinus on CT or MRI. EyeWiki notes that CT is more accurate than Hertel readings but is not used for routine screening, because of radiation and cost. Where a tumour is suspected, MRI is preferred, and the diagnosis is confirmed by biopsy.

Which signs need prompt review?

Any sunken eye after a recent injury, and any sunken eye with double vision, numbness or pain on eye movement. EyeWiki says many people with a floor fracture have reduced sensation over the cheek and lower lid. It lists a complete inability to look upward, fairly severe pain on eye movement, and an unstable circulation as signs of severe muscle entrapment that need urgent intervention.

Prompt review also applies when the change is progressive, when the lid or the eye movement changes with it, or when there is a history of cancer. A one-sided change that has been steady for years is less urgent, but it deserves one proper assessment. The review points out that early sinus drainage may reverse silent sinus syndrome, so a gradual change is not worth waiting out.

How does treatment depend on the cause?

Entirely. The cause decides whether anything needs doing and what.

For a fracture, EyeWiki advises waiting at least 14 days before repairing an isolated floor fracture, and operating when disabling double vision is still present two to three weeks after the injury. The Survey of Ophthalmology review describes the repair as returning the herniated tissue to the socket and rebuilding its shape and volume with an implant. It also says cosmetic concern, with or without double vision, is the main reason to operate for enophthalmos, and that the correction is sometimes not satisfactory, mainly because of undercorrection.

For silent sinus syndrome, the American Academy of Ophthalmology article describes endoscopic sinus surgery to restore drainage, with orbital floor reconstruction using an implant where needed. For symmetrical ageing change, the review notes that fat grafting around the eye does not change the position of the globe, but the fuller lids can improve the appearance. For tumour-related enophthalmos, EyeWiki describes external beam radiotherapy as the main treatment for breast cancer in the orbit, with biopsy to confirm the diagnosis, and this is shared care with an oncologist. For enophthalmos after radiotherapy, the review calls treatment challenging and its results unpredictable.

None of this is a promise about any outcome. If you are unsure which category you are in, start with an examination, ideally by an oculoplastic surgeon. For the wider map, see my overview of orbital conditions and the orbit and thyroid eye disease section. If double vision is part of the picture, my article on double vision that is not a squint explains why. The wider question of why eyes look tired sits in my hub article.