There’s a prevalent misconception we cry when emotionally aroused or when the eye is irritated by invasive foreign substance. In fact, using the more correct medical term LACRIMATION, the eye cries continually even when asleep and has been observed even after death. Actually this type of tearing is by far the most common. Tears consist of three components, mucin, the protein components of mucus, aqueous humour, a water similar to blood plasma and lipids “oils” with the water and mucin distributed from the lacrimal apparatus contained in the outer upper corner of the eyelid while the oil is contributed by another type of gland, the meibomians, on the inner edge of the upper eyelids at the base of the lashes. Tears have many functions above and beyond putting a visual to your emotions or protectively coating the eye when a foreign substance blows in. Tears provide oxygen and nutrients to the surface of the eye, remove waste and bacteria by a flushing washout, lubricate the surface and assist sight by smoothing out microscopic “potholes” on the corneal surface.
The prevalent age grouping for dry eye used to be 55 and older but that demographic is trending downward. The average person blinks 12 to 15 times per minute; however, studies show prolonged visual tasking at computer consoles produces a staring practice reducing the blink activity to a low 4 or5 per minute causing water to evaporate from the eye surface. Same observation applies to children and young adults and their video games. Marathon reading creates a similar scenario. With more people wearing contacts for more protracted periods of time there is a similar impact. None of this should be confused with the effects of allergy nor should we overlook the evaporation effect of prolonged exposure to the drying effect of evaporation in high wind outdoors.
The reason “dry eyes” are rarely dry is the concurrent redness and irritation likened to a foreign body being present inducing a reflex outpouring of lacrimal fluids. It’s true tear production reduces with age creating a cycle of drying, then irritation, then reflex outpouring of imbalanced component ratios in tears; thus reimposing the irritant cycle.
We are also a pharmaceutical-dependent society with any number of antihistamines, cardiac meds, antidepressants and diuretics adversely impacting normal tear production. Cataract surgery, laser vision correction and glaucoma surgery are also known to alter tear film dynamics. There are some auto-immune diseases such as lupus, rheumatoid arthritis and dry mouth Sjögren’s syndrome that will produce inflammatory changes in the lacrimal glands reducing their efficiency.
The diagnosis is straightforward by means of a microscope slit lamp examination of the cornea sometimes augmented by a tear highlighting surface dye (all done with surface anaesthesia drops). There is currently no definitive cure for dry eye but management with regular use of lubricant eye drops at a rate proscribed by your ophthalmic care giver will alleviate most symptoms. An omega 3 supplement daily assists. Wrap around sunglasses reduce glare effect and minimize wind exposure. Hot compresses in the evening will reduce the viscosity of the meibomian oils enhancing their release. Regular breaks from computer and video game terminals will reduce eye strain significantly.
Lastly, DO NOT under any circumstances self medicate with topical antihistamines commonly used for allergic “red eye” itching. They will cosmetically reduce but only temporarily the visible redness but their drying properties will exacerbate the surface irritation long term.
Dr. David Carll