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PLEASE READ THIS: The information contained herein is not intended
as a substitute for medical advice and care from qualified, licensed
health care providers. The reader should regularly consult a
physician in matters relating to his or her health and particularly
with respect to any symptoms that may require diagnosis or medical
attention. The information is presented here to educate and inform
and to guide you to an understanding of cause, prevention as well as
treatment.
(Report revised 10.2006)
Dry Eye Syndrome and the symptoms associated with it is one of most common problems reported to eye doctors.
In this article, I will provide information regarding the
symptoms, causes, diagnosis and
treatment for the clinically dry
eye.
I will post a ’Äúslimmed down’Äù version of this report soon.
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The clinically dry eye is considered to be an ocular surface disease associated with tear film deficiencies or a poorly functioning tear film. The medical term is keratoconjunctivitis sicca. (kerato means cornea, the clear ’Äúwindow’Äù on the front of the eye behind which lies the brown, blue or green iris. The conjunctiva is the normally transparent thin skin-like membrane that covers the sclera, or ’Äúwhite outer shell’Äù of the eye.)The cornea and the conjunctiva require hydration and lubrication to function normally. When these functions are compromised, the symptoms of dry eye occur.
Symptoms include: burning, stinging, a gritty sandy feeling, a foreign body sensation (feels like something stuck under eyelid), itching and often excessive tearing. Sometimes there are strands of stringy mucous present as well.
A common questions is: How can I have dry eye syndrome if one of my symptoms is watering eyes? The answer to that will be revealed shortly!
The treatment of the dry eye focuses on providing substitute artificial tears and lubrication aimed at increasing and enhancing the existing tear production, obstructing the tear outflow to maximize tear contact time with the cornea and other eye tissues, and treatment of the underlying cause if it can be determined.
This last issue is quite important. Certain tear film deficiencies are related to systemic diseases, medications, drugs and environmental causes.
Systemic diseases that may be associated with the clinically dry eye include: Sjorgen's syndrome, thyroid dysfunction, diminished estrogen production, certain auto-immune disorders,lupus erythematosus, Bell's palsy, myasthenia gravis and other neurological disorders effecting lid closure and tear production.
Mechanical causes of dry eyes syndrome include inadequate tear production from the lacrimal gland, excessive tear drainage due to large puncta and drainage canals and poor tear chemistry resulting from lid/meibomian gland disease.
Systemic medications such as beta blockers, antihistamines, and hormones may cause tear dysfunction. Environmental factors such as low humidity can be an issue. Dietary concerns include dehydration, exceessive salt intake and faulty sugar metabolism as in hypo- and hyperglycemia. Additionally, trauma to the ocular surface such as chemical or termal burns and assault by adenovirus can cause the disorder. Post surgery LASIK patients often experience dry eye symptoms as a result of the cornea nerves being severed during the creation of the flap in the initial stage of the procedure.
Drugs and medications are also an issue. Alcohol, and to some degree caffeine, have a dehydrating effect on body fluids in general, smoke from tobacco products are irritants which cause an over production of lacrimal tears resulting in a drying effect (see below). There are numerous medications that effect tear production. These include: anti-anxiety and anti-depression agents, medicines for hypertension, antihistamines and decongestants and other medications.
Environmental causes include: air-conditioning and heating, chemical vapors and smoke, intensive and prolonged near vision tasks. The reason why people engaged in near vision tasks experience dry eye symptoms is due to the fact that the blink rate decreases and this allows the tear film to dehydrate more rapidly. (See article on computers and eyestrain)
It is highly recommended that people who experience dry eye symptoms seek diagnosis and management from an eye doctor. It is often appropriate to address the underlying cause along with and sometimes prior to providing symptomatic relief. Do consult with your eye doctor before beginning treatment!
To understand the cause of the symptoms and treatments, it is useful to know how the tear film works.
Scientifically called the pre-corneal tear film, it is a complex, multi-layer structure. Tthe tears have a number of specific functions:
1. provide water to maintain the hydration of the cornea and carry oxygen and nutritional support.
2. carry anti-bacterial and anti-viral cells to protect the exposed structures of the eyeball from infection.
3. carry off debris so it does not damage the sensitive tissue of the eye.
4. provide lubrication between the inside of the lids and the cornea.
The tear film is actually composed of three separate components: a layer of mucus which lies against the eyeball , a layer of water which is the middle layer and a layer of oil which covers the other two.
There are a number of glands (and the associated ducts systems) that produce these components. They reside in the eyelids and in a special gland called the lacrimal gland above the eyeball. In a properly functioning system, the three elements are produced in perfect balance, mixed and distributed across the eyeball with every blink. You should be unaware of the tear film's existence. Then again, something might happen to disrupt this balance and any or all of the previously discussed symptoms occur.
When the oil or mucus layer is disrupted, our bodies try to compensate in the simplest manner, produce more tears. The problem is that the tears that are produced quickly upon demand are lacrimal tears, consisting mostly of just water and salt. The newly dispensed watery tears simply run off the now destablized tear film. The eyes get dry, red and irritated. The resulting dry spots on the cornea result in more discomfort, which causes more lacrimal tearing, which further destablizes the tear film, etc. An interesting note: when we cry, we are producing excessive lacrimal tears which tends to destablize the tear film causing a dry eye, hence the red, irritated look after crying.
Drops:
The treatment of a dry eye involves re-establishing the normal relationship between the three tear layer components. We use artificial tear replacement drops, of which there are a number of brands and formulations. The primary differences are: preservatives or non- preserved, and the level of viscosity (thickness), and lubricating (slipperiness) agents. Depending upon the severity of tear film dysfunction and symptoms, we treat the dry eye by frequent and proper instillation of the appropriate artificial tear replacement drops. A list of currently available drops follows.
Frequent means every one or two hours. Proper application requires the placement of one drop into the sack created when you gently pull the lower lid out and away from the eyeball. You then close the eyes slowly, open and blink once (to mix the drop with the natural tears) and then close the eyes for 30 seconds. This allows the artificial tears to form temporary attachments to the ocular surface, prolonging the beneficial effects.
This therapy is continued for three to five days (up to two weeks if severe symptoms), then the frequency is diminished---first using the drops every fours hours, then every six hours over the next week or so. You will find that there is a certain frequency of administering the drops that maintains comfort. Sometimes it is possible to slowly taper off the artificial tears completely. It appears that, if the underlying cause is mitigated, the use of tear replacements may stabilize the tear layer situation, allowing the body to resume normal tear film production.
It is not usually appropriate to prescribe tear replacement drops for use as needed or desired By the time the person experiences dry eye symptoms, the tear film has already destabilized, the cornea surface has been impacted and the syndrome has been established. Proper treatment is designed to prevent this situation from occuring by intervening early on in the process and encouraging the body to create a more normal environment.
Mechanical
Additionally, puncta occlusion may be used to reduce the tear outflow from the eye. There are four opening in the eyelid called puncta that drain tears from the eye into the nasal- lacrimal duct and ultimately into the throat. These puncta can be blocked, temporarily with dissolvable collagen plugs (an excellent diagnostic aid), more permanent silicone plugs or permanently by electro-cautery. This procedure is useful as a more permanent treatment for a condition that can not otherwise be mitigated.
Nutritional
Controlling salt and water intake can make a difference. Dietry upplementation with omega 3 fatty acids including flaxseed and fish oils has been shown to be effective, especiallly when the cause of the condition is inflammatory.
Treatment of the lid disease component of dry eye,
including meibobianitis, involves the use of warm compresses, lid scrubs and gentle message a few times daily for three to six weeks, often with continuing parts of the protocol for additional time. Tetracycline-class antibiotics are sometimes used for the treatment of lid-based disease.
Pharmaceutical treatment
includes the use of cyclosporin A (Restasis) and topic steroid or non-steriodal anti-inflammatory drugs.
Note that there are potential side effects using tetracycline-based drugs (photosensitivity/sunburn),immunosuppressents (cyclosporin) and steroids medications. Additionally, omega 3 fatty acids in the dose recommended for dry eye (3-6g per day) may have interactions with other medications and affect certain other diseases.
All are available OTC, no prescription required. PLEASE NOTE: Consult with your doctor for his/her opinion as to which formulation is best indicated for your specific condition. Not all products are compatible with all types of contact lenses.)
When choosing a tear replacement drop, many doctors prefer to use non-preserved products, as the preservatives themselves can exacerbate the symptoms. The down side of preservative free products is their limited shelf life, single use or limited use containers, and the possibility of contamination from misuse. (The tip of the dropper must not contact the eye or fingers.) Users must not allow the packaging to be exposed to extremes of heat and cold. Lanolin-free ointments are preferable for those with allergy to wool.
(in no particular order)
Products containing Carboxyl Methylcellulose (CMC)
TheraTears
This product appears to allow for greater therapuetic effects over a longer period of time between uses and may help stimulate and normalize tear production. Comes in single use containers as well as traditional dropper bottle.
Refresh, Refresh Tears, Refresh Contacts Refresh Plus (Allergan)
Products containing Hydroxyproply Methylcellulose (HPMC)
Genteal (Novartis) comes in PF single use containers and with the disappearing preservative sodium perborate
Bion Tears (Alcon)Similar to Tears Natural Free.
Tears Naturale Free (Alcon)
Products containing Polyvinyl Alcohol (PVA)
Murine Tears
Tears Again
Hypotears PF (Novartis)
Products containing glycerine
Systane (Alcon),Systane PF, Systane Free Gel. Unique formulation contain guar and zinc
Similasan 1(Similasan) A homeopathic and herbal formulation drops
Products containing Castor or mineral oil
Refresh Endura(Allergan)
Soothe (Alimera)
Homeopathic
Viva Drops (Vision Pharmaceuticals) contains vitamin A, but not marketed as therapeutic. Reports are that it is very effective, but no formal double blind controlled studies have been published. Many patients find this one of the best drops for mild to moderate dry eye syndrome.
Similasan 1(Similasan) A homeopathic and herbal formulation drops, very soothing and effective in mild dry eye syndrome.