Orbital fractures from everyday injury: when a knock to the eye needs an eye doctor, not just a scan

The story is almost always the same shape. A ball to the face during a game, a fall, an elbow in a crowded lift lobby, a fist. There is pain, some swelling, maybe a bit of double vision that seems to be settling, and by the time someone reaches my clinic the scan has often already come back and been read as normal or near normal. What people do not expect me to say next is that a reassuring scan does not necessarily mean a reassuring eye. That gap, between what the pictures show and what the eye socket is actually doing, is the entire reason this article exists.

The eye socket, the orbit, is not a single bone. It is built from pieces of the frontal, ethmoid, sphenoid, zygomatic and lacrimal bones fitted together, and some of those pieces, particularly the floor and the wall closest to the nose, are extremely thin. When a blunt force hits the eye or the surrounding area hard enough, one of these thin walls can give way while the rim around it stays intact. That is what a blow-out fracture is, and it is a common injury from exactly the kind of everyday knock most people describe to me. It sits within a wider set of orbit and thyroid eye conditions I see in clinic, most of which have nothing to do with trauma at all, and I have written more broadly about how the orbit behaves when something inside it changes in orbital conditions explained.

How does a knock to the eye actually break the bone behind it?

There are two recognised mechanisms, and knowing which one applies to your injury changes what I am looking for on examination. In the hydraulic mechanism, a blunt force lands directly on the eye itself, without much force reaching the bony rim around it, and the sudden rise in pressure inside the orbit pushes the thinnest wall, usually the floor, outward until it gives way. Sometimes this takes a thin sheet of bone on the nasal side, the lamina papyracea, with it. In the buckling mechanism, the force lands more on the rim itself, and the floor buckles under the transmitted stress rather than the fluid pressure inside the socket. Either way, the result can be the same: a gap in the orbital floor that changes how the eye, and the tissue around it, is supported.

What are the actual warning signs after an injury like this?

Certain findings tell me more than the mechanism of injury ever could. Double vision on looking upward, and a genuine limitation in how far the eye can move upward, both point towards something mechanical rather than simple bruising. Numbness over the lower eyelid and cheek, sometimes extending towards the nose and upper lip, signals that the infraorbital nerve, a branch of the trigeminal nerve that runs along the orbital floor, has been affected. A crackling sensation under the skin, called subcutaneous emphysema, tells me air has escaped from the sinus next to the orbital floor into the soft tissue, which confirms a fracture has actually opened a path between the two spaces.

The finding I take most seriously, though, is any suggestion that one of the muscles that moves the eye has become trapped in the fracture itself, called entrapment. This can cause restricted eye movement, pain, double vision, and in more severe cases pressure on the optic nerve with genuine visual disturbance. It is not a subtle finding once you know to look for it, but it is very easy to miss if the scan is read in isolation from the examination.

Why can a normal CT scan still mean something is genuinely wrong?

This is the point I most want a reader to leave with. Extraocular muscle entrapment remains, first and last, a clinical diagnosis, made by examining how the eye actually moves, not only by looking at the images. Unimpressive findings on a CT scan do not exclude significant entrapment that needs urgent surgical release. A radiology report that says the fracture looks small, or that the muscle appears to be in a reasonable position, is not the same statement as "the muscle is not trapped". Forced duction testing, where the surgeon gently checks how freely the eye can be moved with fine forceps under topical anaesthetic, is one of the tools that tells true mechanical restriction apart from the eye simply being too swollen to move comfortably, and it is particularly useful in a patient who cannot cooperate fully with movement testing because of pain.

Children deserve a specific mention here, because their injuries behave differently. In a child, the bone is soft enough to bend under impact, trap orbital tissue or muscle as it does so, and then spring back towards its original shape, closing over the trapped tissue. The result is what is called a white-eyed blow-out fracture: minimal bruising, minimal swelling, an eye that looks essentially fine from the outside, with a muscle trapped underneath. This combination of a reassuring appearance and a real surgical emergency is precisely why any child with restricted eye movement or persistent double vision after a facial knock needs a proper assessment, regardless of how calm the eye looks.

Why might someone feel sick or faint right after this kind of injury?

There is a reflex worth knowing about that surprises almost everyone who experiences it. The oculocardiac reflex, also called the Aschner reflex, is a genuine drop in heart rate, by more than 20 per cent, triggered by pressure on the eyeball or traction on one of the muscles that moves it, most often the muscle on the inner side of the eye. The signal travels along the trigeminal nerve and back out along the vagus nerve to the heart. What this can look like from the outside is sudden nausea, dizziness, lightheadedness or fainting, and in rare, more severe cases, an abnormal heart rhythm. It matters more in children, whose hearts rely more heavily on heart rate to maintain output than an adult's does. The management principle is simple to state, even though it needs a surgeon to act on it: stop whatever is triggering the reflex, which in an entrapped muscle means releasing that muscle promptly.

What should I actually avoid doing while this heals?

Nose blowing and any strong Valsalva effort, the kind of forceful pressure you create straining or blowing hard through a blocked nose, should be avoided, because both can push air from the sinus into the soft tissue around a fractured orbital floor and visibly worsen the swelling. This is not a fixed number of days. It is advice that holds for as long as the fracture is actively healing, and your surgeon will tell you when that window has closed for your particular injury. Preventive antibiotics are standard practice for anyone with a confirmed orbital fracture, because the break sits directly against the lining of the sinus next door.

When does an orbital fracture actually need surgery, and when does it not?

Not every orbital fracture needs an operation, and deciding which do is a careful judgement rather than a reflex response to any visible break on a scan. Immediate surgery is warranted for a child with a trapdoor fracture whose vital signs are unstable, for bleeding behind the eye causing progressively worsening vision, and for the eye sitting measurably further back in the socket, more than 2 millimetres, at the very first assessment. Beyond those clear-cut situations, surgery becomes the right call where a structure is entrapped without those emergency features, where double vision or a sunken eye persists, or where more than half the floor's surface area has been disrupted.

Timing matters almost as much as the decision itself. Repair is generally done within 14 days of the injury, before the fracture heals into the scar tissue that makes later surgery harder, and most surgeons wait 24 to 72 hours first to let the initial swelling settle. Where a muscle is trapped, the window is shorter: patients are told surgery may be needed within about 4 days, while a less urgent fracture can reasonably wait a week for the swelling to go down. The difference between those two timelines is entirely the trapped muscle. Left without release, an entrapped muscle is at risk of losing its arterial supply and going on to scar or waste, and that is the clinical reason urgency matters here, not caution for its own sake.

If double vision persists even after surgery has addressed the fracture itself, an orthoptic reassessment, a specialist look at how your two eyes are working together, can be arranged, and options like prisms in glasses or a temporary eye patch help manage residual double vision while the eye muscles finish adjusting. Double vision after a knock to the eye is a mechanical problem, entrapment or swelling pressing on a muscle, and it is worth reading separately from the double vision that has nothing to do with trauma at all, which I set out in double vision that is not a squint. A swollen, painful orbit after an injury also deserves to be told apart from an infected one: I cover that separate emergency, and how the two are distinguished, in orbital cellulitis and abscess.

None of this is a reason to fear a knock to the eye more than it deserves. It is a reason to have any injury with double vision, restricted eye movement, numbness over the cheek, or a scan that does not quite match the examination properly assessed by an eye specialist, not filed away as settled simply because the CT report used the word normal. Most of what changes how an eye looks or moves has nothing to do with trauma, and I cover that wider picture in what actually makes eyes look tired, but when a knock is the cause, the scan is only ever the start of the assessment, never the end of it.