Understanding Dry Eye and related conditions of the lid and Cornea
To begin, Dry Eye is a misnomer in that frequently patients do not have a decrease in tears and also their symptoms, blurred vision and or itching are not interpreted as related to tear production or content. Simply put Dry Eye sufferers frequently don’t recognize early symptoms. The attribute them to smog or allergy. This in unfortunate because early diagnosis of Dry Eye and related disorders makes treatment much easier and quicker.
In the past 5 years there has been a leap forward in our understanding of Dry Eye and its relationship to alterations in tear production and content as well as inflammation and the presence of disorders of the secretion of glands in the lids.
The tears or better termed the tear film is made up of 3 layers, each component secreted by different structures in and around the eye. The 3 components form a 3 layer film which on every blink covers and protects the surface of the cornea. The outer layer is made up of lipid or more easily understood as the oil layer. The oil comes from secretions of multiple glands which have exit pores on the lid surface.
The Aqueous portion of the tears which contains water, salt and other factors lies underneath the lipid layer. The next layer, the mucin layer is produced by specialized glands on the surface of the eye. The Mucin layer directly connects to the cells on the surface of the Cornea. When everything is working properly, each blink covers the Cornea, giving the eye its shiny healthy looking surface. A healthy tear film will last between blinks and is crucial to good vision. If the tear film breaks up prematurely, vision is impaired and this premature breakup of the tear film can be measured as diminished tear Break up Time [TBUT]. Diminished tear break up time is one of primary presentations of tear film abnormality
Not infrequently patients will say “I tear all the time but my eyes feel itchy or scratchy. My usual response is ask the patient when the last time they had “good” long cry and how that felt. Usually the response is my eyes were sore and red. That is because causes the Lacrimal gland [located above the eye] secretes excess amounts of aqueous tear which has a high salt content. There is nothing soothing about salt water. In fact people that live near the ocean know how quick moisture from the ocean can corrode metal and ruin pretty much everything else unless it contacts.
It is essential to realize that the ability to produce an adequate volume of aqueous based tears does not mean you have a healthy tear film. Moreover not having a sensation of dryness does not mean you have a healthy tear film.
If you went to your Eye care professional because you were told you need cataract surgery, you want contact lenses or refractive surgery[Lasik] and he/she referred you to me it was because precise measurements of the corneal shape are key to a successful surgical result. If the tear film is abnormal it will cause the cornea to be inflamed and prevent your surgeon from making the precise measurements he needs to give you the best vision possible.
Up until 5 years ago options for the patient with ocular surface disorders were limited. We now have the ability to test for and treat a variety of conditions that disrupt the tear film which leads to abnormalities of the Cornea. At this center we have access to every FDA approved and some experimental treatments available. Some treatments are simple and some are highly technical. Our initial screening tests and your past history will guide our choice of therapy. Although the cornea can heal remarkably quickly, if the tear film problems are allowed to persist, the treatment time may be prolonged and more extensive treatment may be required. There is no simple formula for treating ocular surface problems and we develop an individual treatment plan for every patient.