Dry eyes may not be.
In most cases the problem that exists when someone has "dry eye" is not a problem with dryness at all, although there definitely are people who actually do have a true tear deficiency. These people are the ones that will probably be helped with the use of punctal plugs which prevent the normal drainage of tears and keep more tears on the eye. They are also likely to be helped with the use of "Restasis" eye drops which are a drug which actually stimulates the production of more tears. To better understand what the true nature of the other condition, which seems to be more prevalent, and is a problem with the oil layer of the tear film, it is necessary to explain the nature of the tear film on the eye. The tear film of our eye is made up of three layers. The first layer and the one closest to the eye is the mucin layer which coats the eye and allows the second layer, which is the aqueous layer to spread out evenly. The mucin layer is produced by specialized "goblet cells".The aqueous layer is the thickest layer and makes up at least 90% of the total tear film. It is the layer that is produced by the lacrimal gland and what people call "tears". The top layer which floats on the aqueous layer is the oil layer and is produced by the meibomian glands in the eyelids. The oil layer is very important because it prevents the aqueous layer from evaporating, from breaking up, and from flowing right off the eyeball. In order to help people with "meibomian gland dysfunction" there are several things which are tried before going on to other types of treatment which may be more problematic to implement. The first thing is to apply heat to the eyelids in order to get the meibomian glands to open and put out more oil. The easiest way to do this is to take a nylon stocking and make a small sack which is filled with Uncle Ben's converted rice. This will be placed in a microwave and heated for one minute and will stay hot for the 10 to 15 minutes two or three times a day that it will be applied over the closed eyelids. After that, it is helpful to lightly massage the eyelids with the fingertip to express more oil. The third thing which must be done is to use an eyedrop as needed to help replace the oil layer when the eyes feel dry, or when tearing since tearing means that the oil layer is not keeping the aqueous layer in place. The best drop at this time is one called "Systane Balance" since it is the first to actually mimic and replace the oil layer. Artificial tears in the past were only lubricants. The last intervention added to this regimen is Erythromycin ointment which is placed inside the lower eyelids at bedtime in order to lubricate the eyes while sleeping and to help keep the meibomian glands open. It may also have effects on the meibomian glands that improve their function through a mechanism which has not been totally elucidated. It is also recommended that fish oil be taken daily as well as a multivitamin in order to support the basic physiology of the eye including the oil glands. Beyond these treatments are such things as the punctal plugs and Restasis which may also help if there is also a component of aqueous deficiency. This can be determined with the "Schirmer test" which uses a strip of filter paper to measure tear production over several minutes. Oil layer function is assessed by looking at the oil as it comes out of the glands when pressed by the examiner at the biomicroscope in the office. A normal oil is clear and thin. Abnormal oil is thicker and cloudier. It can get to a point where it resembles toothpaste coming out of the tube. Another way of testing the oil layer is to measure the "tear break-up time". This involves placing a fluorescent dye in the tear film and measuring how long it takes to start breaking up. A time of less than 15 seconds is indicative of a dysfunctional oil layer. Oral Doxycycline can be taken as a short course as it has been found to improve meibomian gland function as well. As a last thought, it can be very good for the eyes as well as the skin to use some type of humidification system to put more moisture in the air especially during the winter months.