Section ONE Preliminaries

6.3.9 Tear dilution test

Rose bengal and fluorescein are both instilled into the tear film which is examined after five minutes. Dilution is detected by a change in colour of the tear prism. In the normal eye it should appear as yellow in colour whereas with a dry eye it typically remains red.

6.3.10 Protein assays

The Lactoplate test consists of a small filter paper disk placed in the lower cul- de-sac for several minutes to collect the patient’s tear secretion. The disk is then transferred to a receptacle containing an immunoreactive gel where a precipitation ring is formed over a three day period. The size of the ring is proportional to the lactoferin concentration of the sample collected.

6.3.11 Tear ferning test

This test is known as the Mucous Ferning Patterns, but also reflects the quality of the tear proteins. Tears are collected with a glass capillary and placed on a glass slide and left to dry at room temperature. The sample is then observed by polarised microscopy and classified according to its appearance following crystallisation. The tears of dry eye patients exhibit reduced ferning patterns compared with normal.

6.3.12 Lacrytest

This test is a rapid assay for total IgE determination in the tears, which can be helpful when deciding if a patient has ocular allergies. The presence and density of control markers on a Schirmer-like strip indicate the total IgE in the tears which should be below 2.5 kUl/l. A higher level is above normal and is a strong indication of ocular allergy.

6.4 Contact lens signs

The typical contact related signs with a dry eye patient are:

Rigid gas permeable lenses

•3 and 9 o’clock staining

•Inferior desiccation

•Surface drying, deposition or areas of non-wetting

Soft lenses

•Inferior arcuate (SMILE) stain

•Superior arcuate (SEAL) stain

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•Surface deposition

•Conjunctival compression ring

•Inferior desiccation

•Upper lid margin staining

6.5 Treatment and management

Treatment goals are to:

•Encourage healing

•Encourage epithelialisation of the corneal tissue

•Re-establish a normal ocular surface

Patient education is very important in the management of dry eyes since compliance with treatment regimens improves the chances of success.

6.5.1 Aqueous deficiency

Aqueous deficiency is dealt with by either tear replacement or tear retention.

Artificial tear supplements

Numerous strategies are available to help deal with the signs and symptoms of dry eye but to date the primary and most commonly used form of treatment is artificial tear supplements. They improve comfort but are also thought to reduce ocular inflammation by reducing tear osmolarity and flushing out inflammatory and other harmful agents. The beneficial effects of artificial tear preparations are transient in nature: this remains their main limitation since solution drainage via the lacrimal system reduces the time that they are in contact with the ocular surface. Contact time can be increased by using more viscous solutions but these tend to blur vision. Some supplements have do not have approval for use with contact lens wear and especially with soft lenses unpreserved products are usually the preferred option.

Low viscosity artificial tears

Free flowing liquids that replace or replenish the tear aqueous element.

•Hypromellose products (isopto-alkaline, isopto-plain) require constant replenishment for most people.

•Carmellose Sodium (Celluvisc) reduces evaporation, remains longer but can cause blurring of vision.

•Polyvinyl alcohol (Liquifilm Tears, Sno Tears) reduces the surface tension to help spreading of the tear film.

•Povidone (Refresh) is a common product for use with contact lenses.

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Viscoelastics

Viscoelastics (thixotropic) are derived from gel polymers. These are high viscosity solutions when stationary but low viscosity during blinking. They therefore exhibit both liquid and gel properties. The liquid state is initiated with blinking and spreads the fluid over the ocular surface; on opening the eyes, gel-like properties are exhibited. Blurring symptoms are much less than with high viscosity products.

•Carbomers (GelTears, Viscotears) have been known to cause allergies.

•Sodium Hyaluronate (Blink, Vislube) is a naturally occurring product.

•Tamarind Seed Polysaccharide and Hyaluronic Acid (Roht®) are naturally occurring viscoelastic products.

High viscosity artificial tears

Ocular lubricants are high viscosity products and come in the form of an ointment. They give resistance to flowing and reduce friction between the palpebral and ocular surfaces.

•Soft Paraffin (Simple Eye Ointment)

•Liquid Paraffin (Lacrilube, Lubritears)

Both are good at night if there are comfort issues on waking.

The ocular surface compromised by dry eye disease is improved by replacing the essential ions and metabolites of the disrupted tear film. Current developments in artificial tears aim at providing ocular protection and improving contact time without compromising ocular health or visual function.

Tear retention

Punctal and intra-canalicular occlusion work on the principle of retaining the tears over the ocular surface by blocking their outflow via the naso-lacrimal ducts.

The lacrimal drainage system is about 40 mm in length. Lacrimal drainage begins at the puncta which should be in apposition to the ocular surface at the nasal upper and lower lid margins. The superior and inferior canaliculi continue for 3-4 mm from each punctum before making a fairly sharp 90°–110° turn nasally and converging at the common canaliculus, the nasal end of which enters the lacrimal sac via the valve of Rosenmuller at the head of the nasolacrimal duct.

Care is required to ensure that punctal occlusion is the most suitable management strategy for a contact lens wearer. It becomes appropriate where all underlying lid disease has been treated and symptoms are not adequately controlled with tear supplements either with or without contact lenses.

Punctal Plug options

Where possible a temporary collagen plug should be fitted but there are problems in obtaining such plugs in Europe due to nvCJD issues with the bovine material.

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A temporary synthetic plug (Lacrimedics Opaque Dissolvable Herrick  Lacrimal Plug) can be used. This dissolves after 2-3 months and is especially useful for those having temporary dry eye symptoms following refractive surgery.

The Medennium Smart Plug is manufactured from thermodynamic hydrophobic acrylic with a heat-induced elastic memory. It becomes a soft gel when exposed to body temperature after insertion and is designed to expand to the size of any punctal canal. The main advantage is that one size fits all, so measurement is unnecessary and there is no protrusion from the punctum which might potentially cause irritation.

Procedure

If it is possible to use a temporary collagen plug, it is good practice to occlude one punctum. In this way the practitioner’s objective findings can be correlated with the patient’s subjective impression of the relative success or failure of the procedure.

The area should be anaesthetised using 0.4% benoxinate or 0.5% proxymetacaine. Small puncta can be dilated using the recommended stainless steel dilating tool. The plug is held gently on the tip of a pair of forceps and eased into  the dilated punctum as the patient looks supero-temporally to avoid corneal abrasion as a result of Bell’s phenomenon. Patients should be monitored  after 4-7 days when they can report any perceived advantages, difficulties or discomfort.

6.5.2 Lipid deficiency

Any associated lid margin disease should be treated. The treatment of meibomian gland dysfunction is aimed at controlling rather than curing the underlying disorder. Standard treatment consists of regular lid hygiene and in unresponsive disease the use of topical systemic antibiotics such as tetracyclines where it is not necessary to use as large a dosage as that required for treating infections.

Lid hygiene involves the application of a hot flannel, cotton wool pad or EyeBags to the lids for a few minutes to warm the meibomian glands and increase the fluidity of the meibomian oils. Secretions can be expressed by squeezing and massage if they are heated to above 37°C. Excessive oil can be removed with a cotton bud soaked in mild shampoo which also helps dislodge scales and other debris which may be present if there is accompanying blepharitis.

Commercial products include:

•Lid Care

•Supranettes, witch hazel and marigold dissolved in water

EyeBag

The EyeBag is more versatile because it has two heat options. It is designed with one side of silver silk and the other of matt black suede which is cooler. The EyeBag is filled with flax seeds (linseed). Flax was chosen for its size, shape and

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density and because of its use as a natural medicinal treatment. The bag is put in a microwave for up to 60 seconds and then applied over the closed eyes for about 5 minutes.

Sprays (e.g. Clarymist)

Clayrimist is a Liposome aerosol eye spray which supplements the bipolar lipid phase usually leached from the lid margins into the tears. The product contains soy lecithin which is the same phospholipid as that found in tears. It also includes Vitamins A and E which are lipid soluble and have anti-oxidant benefits. The fluid is sprayed onto the closed eye to allow the liposomes to make the lids soft and moist. This reduces inflammation of the lid margins which are frequently associated with dry eye symptoms. The preservative, phenoxyethanol, volatises during the aerosol phase minimising skin and eye contact so that the spray can be used during soft contact lens wear.

Delivery of tear supplements

In eye wetting drops are delivered in various forms:

-Multi-dose

-Novel multi-dose, non-preserved (Hycosan, Clarymist)

-Unit dose, non-preserved. Ideal for contact lens wearers. (see Table 6.3)

Prolonged use of preserved drops with preservatives such as benzalkonium chloride, chlorobutanol and chlorhexidine can cause iatrogenic effects and worsen the ocular surface disease.

Table 6.3  Examples of Preservative free and multi-dose eye drops

Blinking exercises

Passive incomplete blinking or reduced blink rate may be helped by actively practicing a regime of blinking exercises. Contact lens wearers are required to

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blink 10 times each in five positions of gaze including the primary position without tightly squeezing the lids. Blinking exercises are normally advised as an adjunct to other strategies.

Diet

The dietary Essential Fatty Acids (EFAs), Omega 3 (Gamma-Linolenic acid) and Omega 6 (Linoleic acid), have a role of moderating the secretions of the lipidproducing glands. Symptoms of dry eye seem to diminish when the intake of EFAs is increased and the tear prism height has been found to increase.13 The ideal diet includes a ratio of 4 : 1 of Omega-6: Omega-3.

Sources of Omega-6 are:

Pecans, Almonds, Walnuts, Sesame seeds, Sunflower seeds, Grape seed oil, Evening Primrose oil.

Sources of Omega-3 are:

Salmon, Mackeral, Sardines, Herring, Cod, Cod liver oil, Flaxseed oil, Walnuts.

6.5.3 Mucin production

Changes in the mucin layer can be due to deficiency (eg Sjogren’s) syndrome or over-production (e.g. CLIPC). There are new products which claim to stimulate the production of goblet cells to counteract any mucin deficiency (eg Thera­ Tears). Dietary intake of Zinc is also speculated to be helpful.

Conjunctival folds

As conjunctival folds alter the apposition of the lid margin against the globe they can contribute to an abnormal tear prism. The folds reduce the amount of fluid available so that friction is increased which in turn increases their severity. Management is directed at making the conjunctival surface more uniform. This can be achieved by ocular lubrication with a gel rather than eye drops. The recommended routine is to use a gel at night (e.g. ViscogelTears (CIBAVision)) and a slightly less viscous liquid lubricant during the day (e.g. Systane (Alcon)). Neither of these is suitable to use during contact lens wear.14

6.5.4 Therapeutic management

Cyclosporine

Topically applied cyclosporin 0.05% has been reported to produce significant improvement in the signs and symptoms of dry eye. An eye drop emulsion, Restasis, is approved by the FDA but not in the UK.15

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