Dry eye

Dry eye, also known as keratoconjunctivitis sicca, is one of the most common eye conditions seen in community pharmacy. Dry eye is both gender and age-related. It generally tends to affect people above 60, and it is more common in women than men. Up to a third of people aged 65 or older may have dry eye. However, it is important to keep in mind that up to 30% of the population will experience dry eye at some point in their lives.

Although dry eye is not usually a serious condition it should not be underestimated either due to its effect on a patient’s health and wellbeing. It is also important to keep in mind that in rare cases, if left untreated dry eye syndrome has caused visual impairment and scarring of the eye’s surface. This condition provides community pharmacists with an opportunity to offer advice and share expertise in the treatment and management of this condition.

 

Figure 1: three layered tear film covering the epithelial layer of cornea

 

Tears serve several important functions:

• Lubricates the eye, keeps it clean and free from dust;
• Protects the eye against infection; and
• Aids sight by helping to stabilise vision.

 

Tears are produced and regulated by a system known as the lacrimal functional unit which consist of lacrimal gland, meibomian glands, eyelid, cornea and tear ducts. If any part of the lacrimal functional unit is interrupted the system can break down, resulting in the quantity (low aqueous flow) and or the quality (excessive tear film evaporation) of the tears being affected. This in turn causes tear hyperosmolarity which causes damage to the surface epithelium of the eye by activating a cascade of inflammatory events at the ocular surface and a release of inflammatory mediators into the tears. Epithelial damage involves cell death by apoptosis, a loss of goblet cells and disturbance of mucin expression leading to tear film instability. This instability exacerbates ocular surface hyperosmolarity and completes the vicious circle.

   

Figure 2:  Lacrimal gland secretes lacrimal fluid onto the ocular surface

 

Aetiology

  A number of factors can interfere with the lacrimal functional unit: Medical conditions: Many people with dry eye also have blepharitis, an inflammation along the edge of the eyelids. There are two types of blepharitis:

• Anterior blepharitis is when the inflammation affects the outside front edge of the eyelids, where the eyelashes are attached. It is often caused by bacterial infection; and
• Posterior blepharitis is associated with dry eye when the inflammation affects the Meibomian glands which are on the inside front edge of the eyelids and produces a fatty liquid that spreads onto the tear film contributing to tear stability and preventing tear evaporation. When dysfunction of the meibomian gland occurs, this leads to hyperosmolarity and instability of the tear film which increases bacterial growth on the eye lid. The increased tear evaporation triggers ocular surface inflammation and possible damage. Skin conditions such as seborrheic dermatitis, acne rosacea and atopic dermatitis can affect oil production of these glands and are linked with dry eye.

 

Environment: Factors such as sun, wind, dry climate, hot blowing air, high altitude can have a drying effect on the eyes. Regular exposure to these environmental factors can cause dry eye syndrome. For example, the combination of dry climate and warm air conditioning found in many offices can cause dry eye in some people.

Occupation: Activities that require visual concentration such as computer work, reading and writing tend to reduce blinking leading to tear evaporation and dry eye.

Medicines: Many commonly prescribed medicines and OTC medicines can cause or exacerbate dry eye in some people. These include antihistamines, anti-cholinergics, anti-depressants, beta-blockers, diuretics, vasoconstrictive eye drops, oral contraceptives, retinoids, anti-arrhythmics.

Laser surgery: Some people after having LASIK surgery can experience dry eye in weeks after surgery. However, the symptoms generally clear up after a few months.

Contact Lenses: Contact lenses can irritate the eye and cause dry eye syndrome. Contact lens wearers are 12 times more likely than non-contact lens wearers to report dry eye symptoms. Changing to a different type of lens or limiting their use, usually helps to resolve the symptoms.

Other possible causes of dry eye:

• Oestrogen/Androgen deficiency- the hormone and nervous system stimulate the production of tears. The imbalance of oestrogen and progesterone levels in menopause contributes to dry eye in women (combination of age and menopause in women is a possible reason why it is more common in women);
• Autoimmune conditions such as Sjögren’s syndrome, Rheumatoid Arthritis, Lupus;
• Shingles, Bell’s Palsy, HIV;
• Chronic Conjunctivitis; and
• Vitamin A deficiency.

 

Symptoms of Dry eye:

• ‘Dry eye’ sensation;
• Sticky eyelids in morning;
• Tired eyes;
• Red, itchy, burning, pain; and
• Foreign body sensation.

 

If any of the following present, immediate referral is advised:

• History of glaucoma (in family);
• Extreme pain and red eyes;
• Deterioration in vision;
• Severe photophobia;
• Recent trauma;
• Unilateral signs; and
• Intolerance to contact lenses (even after a few hours).

 

Figure 3: Location of the Meibomian glands

 

 

Figure 4: Meibomian gland

   

Treatment

 

The aim of treatment is to relieve the symptoms associated with dry eye, return the ocular surface and tear film to its normal homeostatic state, and prevent or minimise possible structural damage to the ocular surface. Although symptoms are rarely eliminated, they can often be improved with treatment.

 

Ocular lubricants (tear substitutes)

 

When choosing a lubricant, it is important to take into consideration certain factors to ensure the best patient compliance:

• Is the applicator multi use, easy to use;
• Does the lubricant give immediate relief;

 

Does blurring of vision occur after application and for how long: Gels have less blurring effect than ointments;

Duration and frequency of use:  Gels have longer retention times than solutions;

• Is it compatible with contact lenses;
• Does it contain preservatives;

 

Preservatives added to prevent bacterial growth in lubricants. Frequent use of preservative drops can cause irritation. If irritation occurs, preservative free formulations are more appropriate for user. Ideally a preservative that completely dissipates before reaching the tear film is best. Ointments generally do not support bacterial growth and do not require preservatives;

Once opened, how long does the product last: 28 days, 3 months, or 6 months; and

• Side-effects.

 

Guideline for treatment of dry eye

Key question: Are the eyes dry due to aqueous deficiency or excessive evaporation?
Features of aqueous deficiency: Unable to produce tears when crying Sore eyes on waking without a history of recent eye injury Pain			Features of evaporative deficiency: Excessive watering on windy day Blepharitis Ocular Rosacea
Aqueous deficiency			Evaporative deficiency
Mild (<4 drops a day)	Moderate (4-6 drops a day)	Severe (>6 drops a day)	Systane Propylene glycol 0.6% eye drops preservative free
Hypromellose 0.5% eye drops	Hypromellose 0.3% eye drops, preservative free	Carmellose 0.5% eye drops, preservative free	Systane Balance Propylene glycol 0.6% eye drops
Polyvinyl alcohol 1.4% eye drops	Sodium hyaluronate 0.2% eye drops preservative free	Thealoz Duo (Sodium hyaluronate 0.15% & trehalose 0.3% drops) preservative free	Advice on lid hygiene
Carbomer 0.2% eye gel			Other options may be recommended in secondary care (VisuXL, Ikervis)
Finding an effective treatment can vary between patients. Try at least two products prior to stepping up to next level of treatment
At night in both aqueous and evaporative deficiency: Paraffin eye ointment preservative free Carbomer 0.2% eye gel		Note: preservative free preparations should be used in the following situations: Patients with ocular surface eye disease Patients with contact dermatitis to           preservatives in eye products Soft contact lens wearers Patients with evidence of punctuate epithelial erosion from use of preservatives Frequency more than 6 times daily or using multiple preserved preparations

 

Role of the pharmacist

Taking into consideration the significant percentage of people in the general population that suffer with dry eye and the fact that community pharmacy serves an older population, pharmacists can play an important role in supporting patients in the management and treatment of dry eye:

 

1. Remain alert and aware of the key symptoms of dry eye;
2. Identify patients that present with Blepharitis and discuss current treatment options they are using. Reiterate the importance of regular compliance with their treatments and good eye hygiene;
3. Review dry eye OTC products currently in pharmacy. Re familiarise with available products, preservative free, multi-use, single use, expiry when opened, compatible with contact lenses and even price point for customers; Identify patients with prescriptions for ocular lubricants. Maybe next time when attending pharmacy have a chat with them about their drops. Do they use them regularly? Do they get relief with drops/ointment/gel? Are they managing ok with administration? Consider an alternate if possible or encourage patient to discuss with doctor;
4. Advise patients about environmental factors (wind, hot air, smoke), which may exacerbate their symptoms. Wrap around glasses may provide good protection. If required, discuss any lifestyle changes to reduce exposure to such factors,
5. Other factors to take into consideration — computer use, take regular screen breaks to help reduce symptoms. Use of a humidifier will add moisture to the surrounding air. Diet —encourage Omega-3 fats intake. The aim is to eat at least two portions of fish a week, one of which should be oily fish.

 

References available on request