WHAT IS DRY EYE?

Dry eye is a multifactorial disease of the ocular surface characterised by a loss of homeostasis of the tear film. It is a general term that is used to describe a range of conditions that affects the surface of the eye.

TEARS

The tears are made up of three layers;


Mucin Layer – the layer closest to the surface of the eye is secreted by goblet cells in the conjunctiva. Its keep the tears on the eye, and provides lubrication.

Aqueous Layer – the middle ‘watery’ portion of the tears is secreted by the Lacrimal and accessory lacrimal gland. Its supplies oxygen to the cornea, washes away debris and has anti-bacterial action.

Lipid Layer – the outer most layer, is secreted by Meibomian glands that are located in the eye lids. This ‘oily layer’ helps reduce evaporation of the tears, and allows the eyelids to glide over the eye.

WHAT CAUSES DRY EYES?

Dry eye is either due to a lack of the watery tear layer (Aqueous deficient) or problems with the oily layer (Evaporative), but is commonly mixed.

People tend to make fewer tears as they get older due to hormonal changes. Both men and women can get dry eye. However, it is more common in women—especially those who have gone through menopause.

Here are some other causes of dry eye:

  • Certain diseases, such as rheumatoid arthritis, Sjogrens Syndrome, thyroid disease, and lupus

  • Blepharitis (when eyelids are swollen or red)

  • Being in smoke, wind or a very dry climate

  • Looking at a computer screen for a long time, reading and other activities that reduce blinking

  • Having refractive eye surgery

  • Taking certain medicines