Dry Eye

Dry eye syndrome is the decline of the quality or quantity of tears bathing the eye. The patient experiences constant pain from eye irritation, and a sandy or gritty sensation that, if untreated, can lead to scarring or ulceration of the cornea, and thus loss of vision.

Normal eye	Dry eye
Ratio women / men is approximately 9/1

• Signs & symptoms
   
  • Foreign body sensation
  • Itching
  • Burning
  • Photosensitivity
  • Redness
  • Pain
  • Inability to produce tears or inconsistent tear film
  • Difficulty in moving the lids

   

• Tears & tear film
  
  Tear secretion:
  The lacrimal apparatus is a complex of glands and ducts jointly secreting tears ( lacrimal gland, accessory lacrimal glands) and also draining them (through the canaliculi,lacrimal sac and nasolacrimal duct)
   

• Tear film
  • Composition of tear film:
    
    
    
    Lipid layer: outer layer secreted from meibomian glands.
    Function : decreases evaporation of aqueous layer , lubricates the eye lid , decreases the surface tension of the tear film.
    
    Aqueous layer:middle layer secreted from the lacrimal gland.
    Function: forms 90 % of the tear film , delivers atmospheric O2 to the cornea and it has an antibacterial effect. .
    
    Mucin layer: inner layer secreted from goblet cells .
    Function : changes epithelial cells in cornea from hydrophobic into hydrophilic to moisturize it with water.
     
  • Function of the tear film :

• Tear deficiency states
  All tear deficiency states produce some degree of damage to the ocular surface, leading to epithelial disruption
   
• Etiology
  Causes are grouped according to the location of the problem

• Causes of dry eye syndrome
  
  Diverse factors cause dry eye syndrome. The normal aging of tear glands, as well as the specific diseases and disorders, may cause changes in the amount and condition of tears produced.
  1. “Sjogren’s syndrome” an immune system disorder characterized by inflammation and dryness of the mouth, eyes, and other mucous membranes, damages the lacrimal glands, and hence affects tear production.
  2. Decreased sensitivity of the cornea can also lead to insufficient production of tears. This lack of sensitivity can be brought on by a disease known as "neurotrophic keratitis" as well as by some types of contact lens wearing.
  3. Excessive evaporation of tears can also cause dry eye syndrome. Such evaporation may be caused by "meibomitis," which results from infection and inflammation of the meibomian glands in the eyelids. People with unusually large eyes, as well as those who suffer from thyroid disease, may also experience dry eye syndrome caused by excessive evaporation.
  4. Dry eye can also result from unusual facial anatomy or irregularities in the cornea, resulting in uneven or inadequate tear coverage of the eye.
  5. Some patients suffer from dry eye as a result of medications such as antibiotics , antihistaminics, diuretics, and anti-diarrhoea, which can dry up the mucous membranes. Hormonal changes can also affect secretions from the tear glands.
  6. Vitamin A deficiency causes loss of conjunctival goblet cells and causing dry eye.
      
• Complications of dry eye
   
  • Exposure keratitis
    Corneal drying due to incomplete blinking.
  • Squamous metaplasia
    Corneal epithelial surface becomes scaly, plate like, dried out.
  • Corneal erosions
    Cell loss from the corneal epithelium.
  • Ulcers
    Due to the shedding of inflamed or dead cells.
  • Mucous plaques
    Adhesion of lipid-contaminated mucin strands so that the tear film fails to remove them.
  • Filament formation
    Threads of mucin adhere to corneal dry spots and are coated by new epithelial cells.
  • Secondary infection
    Decreased secretion of lysozyme, lactoferrin, and secretory IgA.
     
• Risk factors to be watched for Dry Eye Syndrome:
  
  It was found out that
  1. 75% of people over the age of 65 will experience dry eye syndrome. It occurs in both men and women, although:
  2. it is most common in women who are pregnant or post-menopausal.
  3. Patients who suffer from Sjogren’s syndrome and 90% of these patients are women.
  4. People suffering from allergies.
  5. Contact lens wearers are at a higher risk for developing dry eye. 
     
     
• Warning signs and how it is detected?
  
  Early signs of dry eye are:
  1. An occasional burning sensation in the eyes when in areas of low humidity or high pollution.
  2. A gritty sensation in the eyes which is persistent and painful.
  3. An inability to cry under emotional stress.
  4. Decreased tolerance for contact lenses.
  5. In extreme cases of dry eye, patients may become abnormally sensitive to light, experience severe eye pain, or notice diminished vision.
      
  Management of dry eye

1. Artificial lubricants
   Tears Guard
2. Minor surgery
   Punctal closure:
   Closing the opening of the tear drain in the eyelid with special inserts .
   This works like closing a sink drain with a stopper, these special plugs trap the tears on the eye keeping it moist.
   Closure of punctum with collagen or silicon plugs ( removable)