What is Dry Eye?
"Dry eye" is a bad name but is used so commonly that any change is unlikely. A better name would "Chronic Ocular Surface Disorder" but we are likely to have to stay with Dry Eye Syndrome. It is important to understand that tears are complex, and not just "water". Our tear film ages as we do, and become less efficient at providing comfort and good vision. The "Dry Eye Workshop" has pointed out that symptoms from dry eye syndrome are caused by inflammation, and lubricants do not specifically address this. A short course anti-inflammatory drugs may be necessary.
Patients with dry eye syndrome typically complain of "gritty eyes" or a feeling of sand. This may be associated with watering which is technically called "paradoxical epiphora". The paradox is of course having a dry eye which waters! The reason for this is that dry eye syndrome is due to tears not functioning, i.e. lubricating adequately, and this can be due to the quality of the tears being bad even is the quantity is OK. In such circumstances, the failure to lubricate stimulates more tears to be produced and eventually there is over-flow and watering; so a dry eye can be a watering eye!
Good treatment is a complex matter, but includes lubricating drops, gels and ointments; specific dry eye drugs; punctal plugs and surgery. Sometimes changing the drugs you already take, or adding a new tablet can resolve the issue. Exactly what is right for you can only be ascertained at a consultation, and it is helpful if you can bring a list of anything you have tried previously even if it was ineffective. As with all medical treatments, the aim is to reduce or abolish the symptoms with the minimum number of drugs and maximum safety. Sometimes, underlying conditions (such as Conjunctivochalasis as an example) can contribute to dry eye syndrome, and investigations and treatment can occasionally help.
The first line of treatment is to make sure that the environment of the tear film is optimal: this may include treatment of blepharitis, or correction of any lid or lash deformity.
The second line is address the tear film. Commonly there is a combination of "evaporative dry eye" due to Meibomian Gland Disease, and "aqueous deficiency dry eye". The health of the meibomian glands needs to be assessed at a consultation, and if necessary treated (already described in the blepharitis section). One then looks at tear film substitutes or artificial tears. If they contain preservatives, they should be stopped and replaced with preservative-free drops. If evaporative dry eye predominates, then a lipid-containing drop may be particularly beneficial, but the main problem with lubricant eye drops is their short duration of action: not much than 2 hours. Since repeated administration is bothersome, the use of an eye-gel may be better, or punctal plugs which reduce drainage of tear from the eye and allow the lubricants to be retained for longer. Punctal plugs can be fitted in the clinic and is a very low-risk procedure, although occasionally eyes water after they are fitted.
If symptoms are notably bad on waking, this is because humans make no tears when we are asleep. In addition, during "rapid eye movement sleep" we move our eyes a lot, and so the inflammation that creates symptoms is set up during the night and a bad day ensues. This can be relieved by the use of a lubricating ointment used just before sleep. My experience is that a gel does not last the full night, but unfortunately a true ointment does blur vision to some extent so cannot be used during the day.
Occasional patients with severe dry eye syndrome benefit from secretagogues: drugs to stimulate secretion of tears.
Finally, a short course of anti-inflammatory eye drops can be very efficacious in reducing symptoms, and these can be steroids or immune-modulating preparations. A new drug called lifitigrast will soon be available.
Although having dry eye syndrome is not nice, there is good treatment available and if it is individualised it can make a very big difference to symptoms.