The Eye of Sauron seen by an ophthalmologist: can an eye with no eyelid survive?

A giant eye, wreathed in flame, with a vertical pupil, sweeping the horizon and never closing. The image is one of the most famous in modern fantasy. It is also, quite unintentionally, an almost complete clinical case: because in ophthalmology, an eye that does not blink is an eye that is destroying itself. Here is what an examination of that eye would show, and why the question is not as theoretical as it sounds.

THE CASE

Translating the description into medical language

Let’s go back over what Tolkien’s text describes, and sort each element into the column an ophthalmologist would file it under. The eye is rimmed with fire, yellow as a cat’s, its pupil is a vertical black slit, it is “watchful and intent”, it scans relentlessly, it never closes. An eyelid is never mentioned. Sleep is never mentioned.

In a consultation, that list would come out something like: total permanent lagophthalmos, absence of the reflex blink, vertical slit pupil, light-coloured iris. The first item alone would be enough to trigger urgent care. The second genuinely does occur in humans: facial paralysis, described further below, and reduced corneal sensitivity explain it. The third, on the other hand, is anatomically impossible in humans, but perfectly ordinary in other species. The fourth, a light iris, is nothing abnormal in humans: it is simply more common at northern latitudes. And this is precisely what makes the exercise interesting: the author obviously did not think of his character in clinical terms, and yet every trait he gives him corresponds to something documented.

One clarification before going further: I am not going to comment on the film, or on the images taken from it. What interests me here is the written description, and above all what it allows me to explain about an organ most people have never had reason to look at closely — their own.

THE MECHANISM

What blinking is really for

Ask yourself the question honestly: what is the point of blinking? The spontaneous answer is “to keep the eye moist”. That is correct, but a huge understatement. A blink is a piece of maintenance, and it does at least four things at once.

It spreads first a film barely a few micrometres thick over the entire surface of the cornea. This film, the tear film, is not just water: it is structured. An aqueous layer produced by the lacrimal glands, loaded with antibacterial proteins and growth factors. A layer of mucins, secreted by the conjunctiva, which lets water cling to a surface that would, chemically, repel it. And on top, a lipid layer laid down by the Meibomian glands, arranged within the thickness of the eyelid margin, whose role is to slow evaporation.

It then expresses these Meibomian glands: the pressure of the eyelids against each other pushes the meibum out of its ducts. No blinking, no oily layer, and the film evaporates as soon as it forms.

It also pumps. Closing the eyelids creates negative pressure in the tear ducts and draws spent tears towards the nose — which is why you need to blow your nose when you cry. This drainage clears away debris, allergens and inflammatory cells.

Finally, it protects, through the threat-blink reflex, which fires within a few tens of milliseconds, before any conscious decision.

Fourteen times a minute, but with huge variation

A study published in Eye & Contact Lens measured spontaneous blink rate in 100 healthy men aged 23 to 57, filmed for five minutes in silence, looking straight ahead. Result: 13.8 blinks per minute on average, with a standard deviation of 9.7 and individual values ranging from 2.8 to 48 per minute. In other words, the average conceals enormous variability, and the height of the palpebral fissure did not explain these differences.

This figure has a practical consequence I see every day: blink rate falls when you stare at a screen or concentrate hard. This is one of the mechanisms behind screen-related eye discomfort, and it is not corrected with eye drops unless the behaviour that causes it is corrected too.

THE CASCADE

What happens to an eye that never closes

Now let’s take away the eyelid and play out the sequence. It is stereotyped, and that is exactly what makes it predictable.

Step 1 — the film breaks up. Without re-spreading, the lipid layer is no longer renewed, the water evaporates, and the surface becomes exposed in patches. This is measured at the slit lamp and called tear film break-up time. What remains becomes more concentrated in salts: hyperosmolarity. The international TFOS DEWS II report, the current reference on the subject, places this loss of tear film homeostasis at the very heart of the definition of dry eye disease, alongside tear film instability, hyperosmolarity, surface inflammation and neurosensory abnormalities as associated mechanisms.

Step 2 — the surface becomes inflamed. Hyperosmolarity is a stress on the cells of the corneal epithelium. They release inflammatory mediators, which recruit immune cells, which worsen the damage to the surface. A classic vicious circle: inflammation sustains the dryness, which sustains the inflammation.

Step 3 — the epithelium thins out. Points of cell damage appear, scattered at first, then merging together. This is superficial punctate keratitis. In lagophthalmos, it characteristically predominates over the lower third of the cornea — the area the eyelid no longer covers. This distribution is a sign in its own right.

Step 4 — the barrier gives way. When the epithelium breaks down over a continuous area, this is called a corneal ulcer. The cornea is no longer sealed against micro-organisms, and infectious keratitis can take hold on this ground. This is the stage at which visual prognosis is decided, because healing of a deep corneal lesion leaves a permanent opacity on the optical axis. In the most advanced forms, restoring transparency is a matter for graft surgery, whether a full-thickness graft or a selective technique such as DALK.

The point to remember is not the vocabulary, it is the tempo. This cascade does not take years. In a patient whose cornea remains exposed without protection, the first signs appear within days.

IN THE CONSULTING ROOM

Lagophthalmos is not fiction

This is where the exercise stops being a game. The inability to close the eye completely has a name, lagophthalmos, and several very real causes.

The most common is facial paralysis. The facial nerve controls the orbicularis muscle, the one that closes the eyelid; when this nerve is affected, the upper eyelid no longer comes down. A review published in Survey of Ophthalmology notes that Bell’s palsy is the most common cranial nerve disorder in neurology, and that lagophthalmos, exposure keratopathy and corneal ulceration are among its possible complications. This is why, faced with facial paralysis, the doctor managing it prescribes eye protection straight away, without waiting for an ophthalmological opinion.

Next come exophthalmos from Graves’ orbitopathy, where the eyeball is pushed forward and the eyelids are no longer enough to cover it; eyelid malpositions in older adults, such as ectropion, where the lid margin turns outward; after-effects of burns, trauma or a retractile scar; and the aftermath of certain eyelid surgeries when closure has become incomplete.

The most discreet form: nocturnal lagophthalmos

There is a silent version of all this, and it is probably far more widespread than people think: some people do not fully close their eyes while sleeping. A thin strip of cornea stays exposed all night. The phenomenon has been described for a long time — an article in the American Journal of Ophthalmology was already calling it “physiologic lagophthalmos” back in 1969.

A survey of 2,000 people in Japan, published in Life in 2020, found nocturnal lagophthalmos to be significantly more frequent in the group with dry eye disease than in the control group, with a p-value of 0.007. It was also associated with younger age and with ocular symptoms on waking. One methodological point needs to be made: this was a self-reported online survey, not a clinical examination — the figure indicates an association, not a measure of prevalence.

In practice, the sign that should raise this possibility is very simple: eyes that sting, burn or feel stuck on waking, and that tend to feel better as the day goes on. This is the opposite of the usual pattern of screen-related dryness, where the discomfort worsens over the course of the day. This reversed timing is often what puts you on the right track.

AT NIGHT

“It never sleeps”: why this is the most costly detail

In fiction, not needing sleep is an attribute of power. For the eye, it is exactly the opposite: night is when the eye repairs itself.

With the eyelids closed, the surface of the cornea is sealed inside a natural moisture chamber, at a stable temperature, with no evaporation or draught, no dust and no light. The corneal epithelium renews itself continuously, and this prolonged closed phase gives it the most favourable conditions for repairing the areas damaged during the day. This is also the period during which the eyelids stay in contact with the surface, which maintains contact with the residual tear film.

In other words, an eye that never sleeps does not just lose a few hours of rest: it loses its repair window. Every micro-injury from the day adds to the last without being erased. Clinically, this is the detail that most surely condemns the eye described by Tolkien — even more than the absence of an eyelid itself.

CURIOSITY NO. 1

An eye that projects light: an idea 2,500 years old

The eye in the story does not just see: it glows, it sweeps the horizon like a searchlight. This image was not invented for the occasion. Unknowingly, it echoes one of the most persistent theories in the history of science.

In ancient Greece, the theory known as extramission held that vision resulted from a ray sent out by the eye to feel out objects. Empedocles imagined an inner fire; Plato gives an elaborate version of it in the Timaeus. It took until Alhazen, in the early 11^th century, for the direction of travel to be reversed and demonstrated: it is light that enters the eye, not the other way round.

The more unsettling part lies elsewhere. Two American researchers published a series of studies in American Psychologist showing that a notable proportion of adults today, including students who have taken science courses, still subscribe to a form of extramission when questioned using surveys or drawings. The authors note that this belief resists traditional teaching — simply being taught the correct account is not enough to dislodge it.

This is not a throwaway anecdote. It explains why certain myths about vision — “straining your eyes wears them out”, “reading in dim light ruins your eyesight” — get passed down through generations with a solidity that facts do not dent.

CURIOSITY NO. 2

The vertical slit pupil: what it says about its owner

The text lingers on this detail: a vertical pupil, like a cat’s. Here again, the choice is more meaningful than it looks, because pupil shape is not random across the animal kingdom — it correlates with lifestyle.

A study published in Science Advances in 2015 compared pupil shape across numerous land species. The result is clear: vertical pupils are found chiefly in ambush predators, active by day and by night, whose eyes sit close to the ground. Horizontal pupils, by contrast, characterise grazing prey species with laterally placed eyes, whose slit aligns with the horizon.

The explanation the authors propose is a clever one. A vertical slit, combined with the eye’s own astigmatism, produces an asymmetric depth of field: very blurred for distant horizontal contours, sharper for vertical ones. A predator that has to judge the distance to a target precisely, without moving its head and giving itself away, benefits from this. The slit also allows a greater range of constriction than a round pupil, according to the authors, and so an adaptation to considerable swings in brightness — day and night with the same eye.

Translated for our imaginary patient: this eye is described as that of an ambush predator, able to judge distance and function at any hour. Whether intentional or not, it fits the character. In humans, the pupil stays round, and a pupil deformity is never merely decorative: it points to trauma, inflammation or a neurological problem, and warrants an examination.

IN PRACTICE

How to protect a cornea that stays exposed

To finish on something concrete, here is what managing lagophthalmos involves. This is not a fixed protocol: the choice depends on the cause, the severity, and whether the problem is temporary or permanent, and it is decided after examination.

• Preservative-free tear substitutes during the day, at a frequency matched to the discomfort, to make up for a film that blinking no longer renews properly.
• Thick ointment or gel at night, whose viscosity maintains protection over the exposed area during the hours of sleep — the highest-risk time.
• Occlusion or a night-time moisture chamber: an occlusive dressing, a shield, or goggles with a peripheral seal, depending on tolerance.
• Eyelid weight in gold or platinum, placed surgically in the upper eyelid, which uses gravity to help closure. The standard solution for established facial paralysis.
• Eyelid procedures: tarsorrhaphy, which brings the lid margins closer together and reduces the exposed surface, or correction of a malposition such as ectropion.
• Bandage contact lens or amniotic membrane for severe corneal damage, in a specialist setting.

The common principle is simple: as long as the eyelid is not doing its job, something else has to do it instead. And urgency is not judged by the discomfort felt — which can be mild, particularly when corneal sensitivity is reduced — but by the state of the cornea on examination.

TAKEAWAY

What to remember

The Eye of Sauron would not survive. Not for lack of power: for lack of an eyelid. Without blinking, the cornea dries out within minutes, becomes inflamed within days, and then ulcerates; and without sleep, none of this repairs itself. It is a mundane, prosaic, mechanical defeat — that of an organ deprived of its maintenance.

The real lesson is this: the action you perform fourteen times a minute without thinking about it, and have done since birth, is one of the most effective protective mechanisms in your body. You only notice it once it is missing. If your eyes are dry, irritated or stuck together on waking, or if you have noticed that you do not fully close your eyelids at night, this is not a cosmetic detail: it can be checked at the slit lamp. An examination of the ocular surface takes a few minutes, and there is no good reason to put it off.

FREQUENTLY ASKED QUESTIONS

Frequently asked questions

Scientific sources

1. Doughty MJ, Naase T. Further analysis of the human spontaneous eye blink rate by a cluster analysis-based approach to categorize individuals with ‘normal’ versus ‘frequent’ eye blink activity. Eye Contact Lens. 2006. PMID: 17099391
2. Craig JP, Nichols KK, Akpek EK, et al. TFOS DEWS II Definition and Classification Report. Ocul Surf. 2017. PMID: 28736335
3. Nocturnal Lagophthalmos and Sleep Quality in Patients with Dry Eye Disease. Life (Basel). 2020. PMID: 32635438
4. Physiologic lagophthalmos. Am J Ophthalmol. 1969. PMID: 5798819
5. MacIntosh PW, Fay AM. Update on the ophthalmic management of facial paralysis. Surv Ophthalmol. 2019;64(1):79-89. PMID: 29886125
6. Why do animal eyes have pupils of different shapes? Sci Adv. 2015. PMID: 26601232
7. Winer GA, Cottrell JE, Gregg V, Fournier JS, Bica LA. Fundamentally misunderstanding visual perception. Adults’ belief in visual emissions. Am Psychol. 2002. PMID: 12094435

Also worth reading

• Dry eye disease: mechanisms, examination and management
• The cornea: anatomy and conditions
• Keratitis: recognition and treatment
• Dr Moïse Tourabaly — Ophthalmologist

Cachan practice · Tel. +33 1 45 47 08 11

Medical disclaimer

This article is intended for information purposes. A personalised ophthalmological opinion remains essential for any treatment decision.

This article uses a reference from popular culture as an educational starting point; it passes no judgement on the work cited and reproduces none of its imagery. The mechanisms and management options described are general in nature: they do not constitute a prescription or a surgical indication, and the choice of treatment depends on the cause, severity and context specific to each patient. The data cited come from studies whose average results do not prejudge any individual situation. Any persistent eye discomfort, any loss of vision and any abnormality of eyelid closure call for an ophthalmological examination.