Dry eyes, also known as dry eye disease, dry eye syndrome, and keratoconjunctivitis sicca (KCS) is one of the most common reasons for a visit to an eye doctor. The tears have three layers. The innermost layer is the mucin layer. The middle layer is the thickest and is the aqueous layer. The outermost layer is the lipid layer.
Causes of dry eye disease include:
Dry eye disease is more common in women than men and has an increased incidence with aging in both sexes. It has become much more common as more people spend time staring at computer screens. Computer vision syndrome is typically associated with a decreased blink rate and therefore dry eyes. Laser vision correction is a common cause of dry eye, typically for three to four months post-op. Those that have inherent dry eyes also are more prone to have laser vision correction because their contact lenses are uncomfortable.
There are two main types of dry eye syndrome. The first is a deficiency to the water component of the tears because the lacrimal glands fail to produce enough of the watery component to maintain a healthy tear surface. This is found in those with Sjogren syndrome and autoimmune disorders such as rheumatoid arthritis. The lack of water also can be seen in situations where there is poor closure of the lids or where the lids to not adequately touch the cornea. The second type of dry eye syndrome is caused by a problem with the lipid layer which is produced by the meibomian glands. The top oily surface of the tears slows down the rate of evaporation of the tears. In situations such as meibomian gland dysfunction, the oil is abnormal and does a poor job of stabilizing the tear film, allowing the tears to evaporate more quickly. Dry eyes also can occur when there is an inadequate production of surfactant (mucin) to keep the tears sticking to the front of the cornea.
Dry eye syndrome may have any of the following signs and symptoms:
A confirmation of the diagnosis of dry eye disease may best be made by history and with the use of the slit lamp. The magnification allows the practitioner to visualize the tear lake which gives a concept of the amount of tears. A small or non-existent tear lake would suggest aqueous deficiency. The appearance of debris in the tear film is associated with lid disease such as blepharitis. Fluorescein break-up time (FBUT) is determined by measuring the interval between instillation of fluorescein dye and the appearance of dry spots on the cornea. An FBUT of less than 10 seconds is considered abnormal. A decreased FBUT indicates tear instability and is a good sign of overall poor tear function. Classically, Schirmer tests were used to measure the amount of tear production, but fewer practitioners use it now than in the past.
Treatment of dry eye syndrome is usually taken on a step-wise approach and includes the following:
Dry eyes are more commonly seen in women than men and are most common in postmenopausal women. During dry winter months, complaints of dryness is common even among young people, particularly those who wear contacts and spend long hours in front of a computer screen. Some younger patients seem to have significant problems for a few years and then get better. 
Commonly, the issue is the wearing of contact lenses, and the individual, with age, gives up contacts as appearance means less. Others have LASIK removing the added stress of the contacts and becoming more comfortable. Many patients get used to the discomfort and manage their dry eye disease with little thought to its treatment.
There are many causes of dry eyes including the constant staring at the PC screen and use of the smartphone. Sometimes patients may have a collagen vascular disorder. When patients present with chronic dry eyes, it is important to refer them to an ophthalmologist for more workup.
The role of the primary care provider, ophthalmic nurse and pharmacist should be to educate the patient on prevention of dry eyes by limiting screen time, wearing sunglasses when going on, blinking often, using artificial tears and keeping the home environment cool and moist.
The prognosis for most patients with dry eyes is guarded. The majority of treatments work for a short time or not all. Use of artificial tears is also prohibitively expensive in the long run.
|||O'Neil EC,Henderson M,Massaro-Giordano M,Bunya VY, Advances in dry eye disease treatment. Current opinion in ophthalmology. 2019 May; [PubMed PMID: 30883442]|
|||Witte T, [Sjögren's Syndrome: Early diagnosis and effective treatment]. Deutsche medizinische Wochenschrift (1946). 2018 Dec; [PubMed PMID: 30508859]|
|||Odani T,Chiorini JA, Targeting primary Sjögren's syndrome. Modern rheumatology. 2019 Jan; [PubMed PMID: 30424703]|