Trichomes
Derby Eye Surgery
 
Dry Eye (Ocular surface disease)

Introduction:

The term dry eyes (or more accurately ocular surface disease), covers a variety of problems that result in sore, gritty and generally uncomfortable eyes. These symptoms vary from mild discomfort to intolerable pain. It’s a common problem affecting more women than men, particularly in the older population. Until recently it has been thought that it was due either to reduced tear production, excessive evaporation of tears, poor quality of tears or a combination of these. Certain conditions known as autoimmune diseases (rheumatoid arthritis being the commonest), are specifically associated with dry eyes due to reduced tear production. That said the vast majority of people with dry eye symptoms do not have rheumatoid arthritis.

 Artificial tear drops have been the mainstay of treatment. Sometimes this is combined with reducing the tear drainage by blocking the tear drainage tubes in the eyelids. Natural tears are in fact very complicated, containing mixture of water, salt, wax, protein and mucous. Many attempts to replicate tears have been made. As a result there are many different types of artificial tears on the market, all them trying to emulate natural tears with none of them succeeding. Consequently the treatment of dry eyes has been unsatisfactory for both doctors and patients alike. Recently there has been renewed interest in this problem, with the term “ocular surface disease” replacing that of “dry eye syndrome”. This reflects research that has shown the problem is not simply down to lack of tears.  

Causes

Tears are produced by the lacrimal gland, with other glands within the conjunctiva (the covering membrane of the eye) also contributing to their makeup. Deep within each eyelid are twenty or so meibomian glands which produce an important waxy component of the tears. (See diagrams below).  Complicated nerve reflexes help control tear production and quality. The front of the eye requires a constant flow of these tears across its surface. An important function of the eyelids is to evenly spread the tears over the front surface of the eye. As such the eyelids are always in intimate contact with the eye surface. Thus many factors contribute to a healthy eye surface. Maintaining this health is a complex and delicate balancing act.

If this balance is upset the health of the eye surface is compromised, setting off an inflammatory process. Inflammation starting in the front surface of the eye can induce secondary inflammation in the eyelids due to their intimate anatomical association. Conversely, the eyelashes and/or the meibomian glands of the eyelids can become inflamed and set off secondary inflammation on the eye surface. As the Meibomian glands become inflamed this adversely affects the quality of their waxy secretions making the problem worse.

Either way, the immune system is now involved and the inflammation spreads to the lacrimal gland.  If this process persists, protective anti-inflammatory mechanisms break down resulting in a vicious circle of increasing inflammation.
As the lacrimal gland becomes more involved, the quality and quantity of the tears decline which exacerbates the problem. The initial inflammation is usually only at a microscopic level and there is not much to find on looking at the eye. However there are frequently symptoms of discomfort even at this early stage. These increase as the health of the eye surface deteriorates. Once the quality and quantity of the tears degenerates, symptoms worsen. By now there are usually changes visible either on the front surface of the eye, the eyelids, or both.

So what upsets the balance?  It’s thought in most cases to be initiated by an age related reduction in androgen hormone. Whilst this is thought of as a predominantly male hormone it is in fact present in both sexes. Like many hormones it has several roles, one of which is protecting the surface of the eye from inflammation. Sudden reduction in androgens, like that occurring in the female menopause, is thought to be a trigger to ocular surface disease. This would explain why more women are affected as they get older. As men age they also experience a reduction in androgens though this tends to be less drastic than in women.
There are other risk factors especially certain medications. Antihistamines (whatever route they are taken), vitamin A supplements, HRT, tamoxifen, antidepressants, antihypertensives and others have all been implicated. People with autoimmune disease such as rheumatoid arthritis are more at risk. Certain drops such as beta blockers can be a problem as can the preservatives present in almost all drops. Refractive laser surgery is a risk factor too.

Infections of the eyelash roots with a tiny bug caused Demodex can also inflame the eyelids and thus produce symptoms of dry eye.

 

Dry Eyes - Details from Derby Eye Surgery

Diagnosis

Ocular surface disease is diagnosed by examining the front surface of the eye and the eyelids together with assessing the quality and quantity of the tears present.
Special stains are used to see if there signs of damage to the cornea (the front window of the eye) and conjunctiva (the membrane covering the white of the eye). Other changes on the cornea such as abnormal blood vessels are looked for. Tear production is assessed by observing the tears levels in the eye and measuring the amount produced over a fixed time (Schirmers test). A clue to the quality of the tears is how quickly the tear film dries on the eye surface (Tear Break Up Time). None of these methods are wholly reliable at assessing the health of the eye surface or tears. The concentration of tears (osmolarity) is thought to be a better method for grading the health of the eye surface and tears, but this measurement is not widely available.

Eyelid inflammation (called blepharitis) is an important component of ocular surface disease. The eyelashes are examined for inflammatory changes at the roots of the lashes. Behind the eyelash roots are the ducts of the wax-producing meibomian glands. These ducts frequently become inflamed in ocular surface disease. The state of the secretions of these glands is another indication as to whether or not they are healthy. Using all this information the type and severity of the disease is graded.

Dry Eyes - Details from Derby Eye Surgery

As we have seen, ocular surface disease has multiple causes and features. Therefore different therapies are often required for various aspects of the disease, so treatment has to be tailored to each individual. Some people will respond to simple treatment whilst others will not. For those that do not there are a variety of treatment options escalating in their complexity dependant upon the type and severity of the disease.

Treatment

Artificial tears are still important in the management of ocular surface disease. This is especially so when the problem is relatively minor or predominantly down to reduced production of natural tears, as occurs in the autoimmune conditions. Whilst there are many different artificial tear products available, there are three basic types. These are: liquids (thin), gels (thicker) and creams (very thick). The liquids disturb vision the least but don’t last as long. The gels cause more blurring but last longer. The creams cause prolonged blurring and are generally used before going to sleep. There are many variations in these artificial tears such as type of lubricant, electrolyte (salt) balance, reduced or no preservatives, and mucous content. Naturally the manufacturers all claim their product is the best, but in reality none of them are as good as the real thing.

It’s a matter of finding out which lubricant suits a particular individual best in relation to easing the discomfort with minimal inconvenience. Some people find they only need to use lubricants once or twice a day. Others need to use them more frequently whilst many people’s requirements vary from day to day.

It has long been recognised that people with inflamed eyelash roots are more prone to sore, gritty eyes. A traditional approach to this has been termed “lid hygiene”. Cleaning the lids and lashes with dilute bicarbonate of soda (or better still cleaning wipes that are available from pharmacists). This helps clean away normal skin debris (sometimes called eyelash dandruff) that can cause irritation.

Keeping the Meibomian glands healthy and clean is also important. The waxy secretions of the glands often solidify when the glands are inflamed making the situation worse. Gently warming the lids melts the wax and if this is followed by massage of the eyelids (just rubbing your eyelids like a tired toddler) encourages normal gland secretions. There are eyelid heating products available at pharmacists, though a warm flannel will also do the job

Another treatment is to reduce the outflow of tears thereby retaining more of the natural tears on the surface of the eye. There is a tiny tube in the inner corner of each upper and lower eyelid through which tears constantly drain. The entrance to the tube (the punctum) can be blocked thus reducing tear drainage. Using these “punctual plugs” can be successful sometimes to the point of producing a watery eye! There are several types on the market with the newer ones being available in different sizes and lengths depending on how much blockage is required.

Artificial tears, lid hygiene and punctual plugs tend to be most useful for mild ocular surface disease. In many people this is all that is required. However if there is increasing inflammation of the eye surface and/or the eyelids together with reduction in the quality of the tears, these treatments are (or become) less effective. Nowadays other treatment options exist aimed predominantly at modulating the inflammatory process.

It is now recognised that certain medications such as antihistamines and vitamin A supplements can exacerbate the disease. Stopping these and other drugs may help, but this is not always an option and should be done under the guidance of a doctor.

Managing co-existing lid inflammation is important. Lid hygiene has been mentioned although it is frequently not performed adequately or often enough.
If the meibomian glands are inflamed many people will respond to an anti-inflammatory tablet called doxycyclin, taken usually for two or three months. Sometimes a more prolonged treatment is required.

A newcomer is azithromycin (Azasite) which is available as a drop. It’s related to doxycyclin and reduces lid inflammation and improves meibomian gland function. Unlike doxycyclin it does not need to be used for a prolonged period. At the time of writing in the UK azithromycin in not licensed for more than a few days.

It is known that tiny bugs live in the roots of many peoples eyelashes (demodex). Some experts believe these cause eyelid inflammation as well and specifically eradicating them can help control the inflammation. Tea tree shampoo and similar products are available for this. Other experts however do not agree and feel that the treatment is more uncomfortable than the symptoms.

Cyclosporin (restasis) is a potent anti-inflammatory drug that is available as a drop or cream. It can relieve severe symptoms of dryness and grittiness even when the eye surface or lids are not obviously inflamed; the logic being that inflammation is the driving force behind the problem. Unfortunately it causes stinging on instillation for the first few weeks and whilst available in the UK, is not easy to get hold of.  

Omega 3 is a fatty acid found in many foods especially oily fish. It reduces inflammation generally and so can improve symptoms of ocular surface disease. In addition it reduces the risk of heart disease, particularly in men. Taken as a dietary supplement, it is cheap and readily available. Some say the stronger “pharmacy grade” supplements are the best.

Recently other methods of reducing Meibomian gland inflammation have come to the fore. These involve using pulsed light to soften the secretions or devices that are applied to the lid (Lipiflow) which accurately warm the secretions allowing a more thorough massaging of the glands. Also the ducts of the glands can be probed to further encourage free flow of the secretions.

Dry Eyes - Details from Derby Eye Surgery

Heating the eyelids with lipiflow

Summary

Dry eyes are not simply due to a lack of tears. The symptoms are a product of ever increasing inflammatory changes involving the front surface of the eye, the eyelids, and lacrimal gland. Ultimately there is a reduction in both the quantity and quality of the tears. This all combines to produce worsening symptoms of discomfort. The modern term for this is ocular surface disease. This disease is common though frequently under diagnosed. Treatment up to now has involved using artificial tears, reducing tear drainage and lid hygiene. This works in some but by no means all cases and is a cause of frustration for many patients. There are other treatment options available which are worth exploring especially in more severe disease. The idea is to target the underlying inflammatory disease in the eyelids and surface of the eye. These treatments include ant-inflammatory drops, long term antibiotics and more sophisticated management of Meibomian gland inflammation. With time and patience this previously poorly understood condition can be successfully managed.

Useful link: www.dryeyezone.com

 

 

 

General eye problems

Adult Squint
/
AMD
/
Presbyopia and normal ageing of the eye
/
Cataract
/
Cataract FAQ's
/
Refractive surgery of the lens and correction of presbyopia
/
Dry eye
//
Glaucoma
//
Retinal Vein Occlusion

 

Derby Eye Surgery

Appointments. Tel. 0300 790 6190
NHS enquiries. Tel. 01332 787512
Secretary. Tel. 01332 510784
Email. rhoeyes@googlemail.com

 
 
 
 Roger Holden Eye Surgeon
 
Home | About us | Contact us | Useful links | Location | Site map - © 2010 Derby Eye Surgery