Dry Eye 

Dry Eye is a very common condition, with many symptoms, but often discomfort or variable vision and one  sign can be the eye looks a little red. 

The tears are often assumed to be made simply from water, and if the eye waters then the tears must be ok. This is not the case. Tears are very complex and a watery eye could signify the eye is not being well lubricated. 

The tears are made of three main components, mucus, grease and water. The mucus is produced from the surface of the eye, the grease from glands close to the eye lashes and the water is produced by the lacrimal gland. If the tear volume is reduced, it causes damage to the mucus layer and causes an inflammatory response. The grease stabilises the tear layer, and if the grease secretion is compromised the tears film may be stable for less than 10 seconds before some dry patches appear. 

We have the equipment to measure tear volume and tear stability. We can asses the thickness of the grease ( lipid ) layer. 

Dry Eye Disease results in symptoms of discomfort, visual disturbance and tear film instability and it has the potential to damage the ocular surface. It is accompanied by increased osmolarity of the tear film and inflammation of the ocular surface. The best ways of confirming the diagnosis of dry eye disease are:

  • Assessment of how strong the salt concentration is in the tears  - their osmolarity.
  • Measurement of tear stability.

Tear Stability

We use equipment which has automatic detection of where and when the cornea starts to dry. This is called non invasive tear breakup time. Under 10 seconds suggests poor quality tear film. The equipment detects the time taken for 10% of the corneal surface to have broken up ( dried out )

Lipid Layer Thickness

The quality of the lipid layer produced by the meibomian glands can be assessed using interferometry, and then graded.

Using infra-red light the glands that produce grease can be visualised, from this the number of glands that have failed can be assessed. The equipment automatically shows the percentage loss.


Tear Volume

The tears are very thin across the front of the eye, but any surplus watery volume pools just above the lower lid, this pooling is called the tear meniscus. The equipment automatically detects the meniscus and measures its height in mm. A small height indicates a dry eye, or more specifically and aqueous dry eye.


A sign of the quality of tears is to check how salty they are. Higher salt levels are a sign of dry eye disease. The equipment automatically measures the concentration of salt in the tears - known as osmolarity.


The report shows the quality of the tears and from this can give an indication on how to treat the dry eye, which can be anything from drops, wipes, warm compresses, lid scrubs, and moisture goggles.

There are new treatments available which include IPL and LipiFlow which can have dramatic results for certain kinds of dry eye condition.