Dry Eye Syndrome (Keratoconjunctivitis Sicca): Causes

Pathogenesis (disease development)

Normally, the main lacrimal gland as well as numerous small glands (accessory lacrimal glands and meibomian glands/specific sebaceous glands of the eyelid gland that produce the outer lipid film of the lacrimal film) produce the tear fluid in sufficient quantity. The blinking of the eyelids distributes the fluid so that the eye is kept evenly moist. The condition is divided into:

  • Dry eyes with decreased tear production (hypovolemic); indicate: decreased tear film meniscus and reduced umbrella test.
  • Dry eyes with increased evaporation of the tear film (hyperevaporalativ); for it speak: pathologically altered lid edges, a thickened meibomian gland secretion or obstructed meibomian gland excretory ducts; the tear film break-up time is decreased

The hypovolemic form exists in 10% of patients. In about 80% of cases, a hyperevaporative / hypovolemic mixed form is present Triggers of dry eye can be various diseases, but environmental factors (exogenous factors) such as air conditioning also have a major impact on the eye. Primary keratoconjunctivitis sicca is a typical secondary disease or complication of sicca syndrome (Sjögren’s syndrome). For secondary forms, see etiology (disease-related causes).

Etiology (causes)

Biographic causes

  • Genetic burden – lacrimal gland aplasia (incomplete development of lacrimal glands).
  • Lagophthalmos (incomplete closure of the eyelids).
  • Altered tear composition
  • Age – decreasing tear production
  • Hormonal factors – menopause (timing of the last spontaneous menstruation in a woman’s life).
  • Occupations – occupations with intensive screen work.

Behavioral causes

  • Nutrition
    • Low fluid intake
    • Micronutrient deficiency (vital substances) – see Prevention with micronutrients.
  • Consumption of stimulants
    • Alcohol (tear film break-up time↓ (beak up time, BUT), tear film osmolarity↑).
    • Tobacco (smoking, including passive smoking) [1,2]
  • Wearing contact lenses
  • Intensive television

Causes related to disease

  • Allergic rhinitis (hay fever)
  • Diabetes mellitus
  • Facial paresis – paresis (paralysis) of muscles innervated by the facial nerve, consequently part of the facial musculature is paralyzed
  • Hepatitis C
  • HIV/HTLV-1 infection
  • Infections with mumps or trachoma
  • Neurodermatitis – in neurodermatitis patients due to pollen.
  • Leukemia (blood cancer)
  • Rheumatoid arthritis – chronic inflammatory multisystem disease, which usually manifests itself in the form of synovitis (inflammation of the synovial membrane). It predominantly affects the joints (polyarthritis, ie arthritis of ≥ 5 joints), more rarely other organs such as eyes and skin.
  • Sarcoidosis – systemic disease with increased cellular immune activity in the affected organs, mostly affecting the lungs and lymph nodes.
  • Sjögren’s syndrome (group of sicca syndromes) – autoimmune disease from the group of collagenoses, which leads to a chronic inflammatory disease of the exocrine glands, most often the salivary and lacrimal glands; typical sequelae or complications of sicca syndrome are:
    • Keratoconjunctivitis sicca (dry eye syndrome) due to lack of wetting of the cornea and conjunctiva with tear fluid.
    • Increased susceptibility to caries due to xerostomia (dry mouth) due to reduced salivary secretion.
    • Rhinitis sicca (dry nasal mucous membranes), hoarseness and chronic cough irritation and impaired sexual function due to disruption of mucous gland production of the respiratory tract and genital organs.
  • Stevens-Johnson syndrome (dermatostomatitis Baader) – infectious or drug allergic skin disease symptoms: painful blisters in the mouth, throat and genital area and erosive conjunctivitis (eye conjunctivitis).
  • Viral infections – conjunctivitis follicularis.

Exogenous (external) factors that may be a cause of dry eye (keratoconjunctivitis sicca):

  • Environmental factors
    • Insufficient or incorrect lighting
    • Dry room air (low humidity) wg.overheated rooms, underfloor heating, air conditioning.
    • Car fan
    • Ozone, e.g. from copiers and printers
    • Cigarette smoke
    • Environmental pollution (e.g. dust)
  • Activity at the computer screen (screen work, office eye syndrome, gamer eye in computer games).
  • Intensive television
  • Wearing contact lenses (friction between the cornea / conjunctiva).
  • Preservatives in tear substitutes (surfactants destroy lipid layer).

Medication

Surgeries

  • Corneal refractive surgery (eye surgery that changes the refractive power).

Radiotherapy

Environmental exposure – intoxications (poisonings).

  • Exhaust fumes
  • Car fan
  • Low humidity, which means, among other things, dry indoor air due to overheated rooms, underfloor heating, air conditioning systems
  • Ozone, for example, from copiers and printers.
  • Insufficient or incorrect lighting
  • Cigarette smoke
  • Environmental pollution (e.g. dust)
  • Draft