Conditions That Can Look Like Dry Eye

There is another important possibility. It does not always have to be dry eye OR another condition. Sometimes it is dry eye AND another condition.

For example, someone may have an eyelid problem that contributes to dry eye while also producing symptoms of its own. Another ocular-surface condition may irritate the eye and at the same time make the tear film less stable.

So finding another condition does not automatically rule dry eye out. The two may coexist.

Allergic eye disease can cause:

• •redness
• •watering
• •irritation
• •burning
• •swollen eyelids
• •discomfort

That can sound very similar to dry eye. One particularly useful clue is itching. Strong itching — especially when accompanied by swelling or a clear relationship with allergens — can make allergy more likely.

But even this is not absolute. Allergy and dry eye can coexist, and inflammation associated with allergy can also affect the ocular surface. So the question is not simply “Do my eyes water?” It is the entire pattern of symptoms and clinical findings.

The eyelids themselves can produce symptoms that feel like dry eye. Inflammation around the eyelashes, abnormal eyelashes rubbing against the eye, changes in eyelid position, blocked glands and other eyelid disorders can all cause:

• •irritation
• •foreign-body sensation
• •redness
• •watering
• •discomfort

This is one reason a proper dry-eye examination should include the eyelids and eyelashes, not just the centre of the eye. Sometimes the clue to a patient’s “dry-eye symptoms” is sitting right at the lid margin.

Blepharitis is inflammation involving the eyelids, particularly around the lid margin. It can cause burning, irritation, crusting and uncomfortable eyes. Demodex mites can also be associated with a particular form of blepharitis. One clue clinicians may look for is characteristic debris around the base of the eyelashes, often called collarettes.

But these conditions are particularly interesting because they do not sit neatly on the other side of the dry-eye diagnosis. They can exist with dry eye and may contribute to it. So identifying blepharitis or Demodex does not necessarily end the investigation.

The cornea and conjunctiva form much of the exposed ocular surface. Problems affecting these tissues can produce symptoms that resemble dry eye. Examples include:

• •small injuries or abrasions
• •recurrent corneal erosion
• •inflammation of the cornea
• •infections
• •abnormal areas of conjunctival tissue
• •irritation caused by something trapped on or under the eyelid
• •changes following eye surgery or other procedures

Some of these require very different treatment from ordinary dry-eye management. That is one reason persistent or unusual symptoms should not simply be treated indefinitely as “dryness” without a proper eye examination.

Eye infections can cause redness, watering, irritation and discomfort. But there may be additional clues such as:

• •discharge
• •significant redness
• •swelling
• •rapid onset
• •one eye being much more affected than the other

These features do not automatically mean infection. But they are reasons to look more carefully rather than assuming dry eye.

Contact lenses interact directly with the tear film and ocular surface. A contact-lens wearer can certainly have dry eye. But discomfort while wearing lenses can also involve other contact-lens-related problems.

The lens itself may affect tear-film behaviour. There may be mechanical irritation. The corneal surface may be affected. There may be inflammation or, more rarely, infection.

So “My eyes become uncomfortable in contact lenses” does not automatically tell us which mechanism is responsible.

This sounds strange because eye drops are supposed to help the eyes. But some topical medications — particularly when used frequently or in combination — can irritate or alter the ocular surface. Preservatives or active ingredients may sometimes contribute.

That is why a clinician should know everything you regularly put into your eyes, not only prescription medications. This includes over-the-counter eye drops.

Dry eye can certainly be painful. But significant eye pain deserves careful assessment. Pain that seems unusual, severe or very different from ordinary irritation can have causes other than dry eye.

And sometimes the source of pain may involve the sensory nervous system rather than only visible damage to the ocular surface. This is particularly relevant when symptoms are much more severe than routine examination findings would suggest. That does not automatically mean neuropathic pain. It means that the mismatch itself may deserve further investigation.

Not all sensations felt around the eye actually originate from the ocular surface. Certain headache disorders can produce pain around or behind the eyes. Light sensitivity may also occur with migraine and other neurological conditions.

A person can, of course, have both migraine and dry eye. But if pain or light sensitivity is a major feature, it may be important to consider whether more than the tear film is involved.

Dry eye does not have to affect both eyes equally. But a very large difference between the eyes can sometimes suggest that something else deserves attention. For example:

• •one eye is dramatically redder
• •one eye suddenly becomes very painful
• •one eye develops significant discharge
• •symptoms begin abruptly in only one eye

These patterns do not diagnose a particular condition. They simply tell us: look more carefully before assuming this is ordinary dry eye.

The history of the problem can sometimes be as informative as the symptoms themselves. Did everything develop gradually? Or did it begin suddenly? Did symptoms start after:

• •eye surgery?
• •an injury?
• •an infection?
• •starting a new medication?
• •beginning contact-lens wear?
• •exposure to a chemical or other irritant?

The answer may completely change what needs to be investigated. This is why a good dry-eye consultation should involve more than performing a series of tests. The story matters too.

TFOS DEWS III suggests several simple questions that can help clinicians recognize when something other than — or in addition to — dry eye may need to be investigated. For example:

• •Is this mainly discomfort, or significant pain?
• •When did it start? Was there a particular trigger?
• •Is vision affected — and does blinking improve it?
• •Is one eye much worse than the other?
• •Do the eyes itch?
• •Is there swelling, crusting or discharge?

These questions do not diagnose the condition. They help determine where to look next.

Most dry-eye symptoms are not medical emergencies. But some eye symptoms should not simply be watched at home or assumed to be dryness. Seek prompt professional assessment if you develop symptoms such as:

• •sudden or significant loss of vision
• •severe eye pain
• •marked light sensitivity
• •a very red and painful eye
• •significant eye injury or chemical exposure
• •a rapidly worsening eye problem, particularly if one eye is much worse than the other

The purpose is not to make every episode of eye irritation frightening. It is simply to recognize that not every uncomfortable eye is a dry eye.