Dry eyes occur when one does:

• Not produce enough tears
• Not the right quality of tear or tears that evaporate too quickly.
• It is important to treat to prevent eye infection, eye injury and maintain the function of the eye.
• Almost half of all sufferers have meibomian gland dysfunction, where the meibomian gland (along the edge of the upper and lower eye lid) produces an oil-secreting layer to prevent tears from evaporating, this is usually diagnosed by your optician.

Tests include:

• Optrex blink test
• Systane non-invasive tear break-up time test
• Fluorescein dye test (a vital dye thought to stain dead and dying cells principally on the cornea)
• Schirmer’s test (an invasive filter paper strip folded over the lower lid to absorb the tear film for a period of five minutes)

Source: Smith JA, Albeitz J, Begley C et al. Ocul Surf 2007;5:93–107

Eyelid twitch

• An eyelid twitch (myokymia) is a repetitive, involuntary spasm of the eyelid muscles. A twitch usually occurs in the upper lid, but it can occur in both the upper and lower lids.
• These spasms are mild and feel like a gentle tug on the eyelid
• Episodes of eyelid twitching are unpredictable.
• The twitch may occur on and off for several days. Then you may not experience any twitching for weeks or even months.The twitches are typically painless and harmless, but they may bother you. Most spasms will resolve on their own without the need for treatment.

Causes

• Mainly dehydration (not enough water)
• Drinking too much caffeine, smoking (tobacco) and/or alcohol
• Environmental irritants, such as wind, bright lights, sun, or air pollution
• Exposed to air conditioned rooms
• Driving
• Fatigue (tiredness) or lack of sleep
• Physical exertion
• Stress and anxiety
• Dry eyes
• Eye irritation, strain, or corneal abrasion
• Light sensitivity
• Uveitis and/or or swelling of the middle layer of your eye
• Blepharitis, or inflammation of your eyelid
• Conjunctivitis (pinkeye)
• Migraine episodes
• Medication

Serious underlying condition to consider:

Eyelid spasms are a symptom of a more serious brain or nerve disorder. When eyelid twitches are a result of these more serious conditions, they’re almost always accompanied by other symptoms.

Brain and nerve disorders that may cause eyelid twitches include:

• Bell’s palsy
• Brain damage from inflammation or a stroke. This is especially true for the thalamus, basal ganglia, or brain stem
• Dystonia, which causes unexpected muscle spasms and your affected area’s body part to twist or contort
• Cervical dystonia (spasmodic torticollis), which causes your neck to randomly spasm and your head to twist into uncomfortable positions
• Meige syndrome (nervous system movement disorder)
• Multiple sclerosis (MS), which is a disease of the central nervous system that causes cognitive and movement problems, fatigue, and eye twitching
• Parkinson’s disease
• Tourette syndrome
• Reaction to certain mental health medicines

Benign essential blepharospasm

• If the spasms become chronic (long term), you may have what’s known as benign essential blepharospasm, which is the name for chronic (long term) and uncontrollable winking or blinking.
• This condition typically affects both eyes (both eyes close or twitch at the same time) and is more common in women than in men.
• The condition will likely worsen over time and may cause problems with the muscle groups around your eye. and it may eventually cause:
  • Eye irritation (often a first symptom)
  • Increased rate of blinking
  • blurry vision
  • Light sensitivity
  • Dry eyes
  • Vision problems, if twitching is frequent
  • Facial spasms

Cause

• Unknown
• Having certain genes (family history)
• Head injury may increase your risk for eye twitching
• Problems with the basal ganglia (a part of the brain)

Hemifacial spasm

• If the eyelid twitch affects just one eye.
• This type of spasm is a neuromuscular disorder usually caused by a blood vessel putting excess pressure on one of your facial nerves.
• This disorder is more common in women than in men, and it’s also more common in people from Asia.
• If left untreated it may cause:
  • frequent, uncontrollable eye twitching
  • an inability to open your eye
  • twitching in all muscles of one side of your face

Healthline

Cedars-Sinai