As the tear film is made up of three distinct layers, a problem at any one of these layers can cause symptoms of dry eye.
The outer most layer of the tear film is formed of lipids which are produced by the glands which run vertically in the eyelid, called the meibomiam glands. This layer prevents tears from evaporating form the eye surface. Below this lies the aqueous layer of the tear film, which is produced by the lacrimal gland, and largely helps lubricate the eye surface, along with providing an antibacterial function. The inner most layer is the mucous layer which is formed by glands from the white part of the eye, the conjunctiva.
- Light sensitivity
- Blurred vision
- Redness (See Figure 1.0)
Though lots of these symptoms can be constant, they will often be made worse in certain conditions, such as in very hot or cold environments.
Sometimes other simple measures such as using hot compress massage against closed eyelids can act in a more natural way to supplement the tear film. This works by thinning and releasing the oils within the meibomiam glands in the eyelids.
If simply supplementing the tear film is not adequate, then further methods can be used such as inserting very small silicone plugs into the tear drainage system to allow the tears to be on the eye surface for longer.