Dry Eye - Treatment 4/4

Treatment of Dry Eye

I. Treatmemnt Strategy

• The causative processes of dry eye are generally not reversible and management is therefore control of symptoms and the prevention of surface damage. 
• According to dews (dry eye workshop); suggested treatment options depend on the level of severity of disease graded from 1 to 4.

Level 1:

1. Education and environmental/dietary modifications:

• Lifestyle review including the importance of blinking whilst:
• Reading, 
• Watching television or using a computer screen, and 
• The management of contact lens wear.
• Environmental review, e.g.
• Increasing humidity may be possible for some environments. 
• Laser refractive surgery can exacerbate dry eye

2. Systemic medication review:

• To exclude contributory effects and eliminate offending agents. 
• Discontinuation of toxic preserved topical medication if possible.

3. Artificial tear substitutes including gels and ointments:

• Some authorities advocate that use of preserved drops should fall within level 1. 
• Mucolytic agents may be specifically indicated for some patients.

4. Eyelid therapy:

• Warm compresses and lid hygiene: for blepharitis, 
• Reparative lid surgery: entropion, ectropion, 
• Taping the lids: in nocturnal lagophthalmos

Level 2:

• Non-preserved tear substitutes are categorized as level 2 treatment by some authorities.
• Anti-inflammatory agents such as topical steroids, oral omega fatty acids and other agents such as topical ciclosporin.
• Tetracyclines (for meibomianitis, rosacea).
• Punctal plugs.
• Secretagogues, e.g. Pilocarpine, cevilemine, rebamipide.
• Moisture chamber spectacles and spectacle side shields.

Level 3:

• Serum eye drops: Autologous or umbilical cord serum.
• Contact lenses.
• Permanent punctal occlusion.

Level 4

• Systemic anti-inflammatory agents.
• Surgery
• Eyelid surgery, such as tarsorrhaphy.
• Salivary gland autotransplantation.
• Mucous membrane or amniotic membrane transplantation for corneal complications.

II. Tear substitutes:

• Tear substitutes have a relatively simple formulation that cannot approximate the components and structure of the normal tear film.
• There are no mucus substitutes and paraffin is only an  Approximation to the action of tear lipids.
• Available forms are:

a. Drops and gels:

• Cellulose derivatives  are appropriate for mild cases. E.g.
• Hypromellose, 
• Methylcellulose
• Carbomer gels adhere to the ocular surface and so are longer-lasting, but some patients are troubled by slight blurring.
• Polyvinyl alcohol (PVA): which increases the persistence of the tear film and is useful in mucin deficiency, e.g.
• Sodium hyaluronate, 
• Povidone, glycerine, 
• Propylene glycol, 
• Polysorbate and others.
• Diquafosol is a newer agent that works as a topical secretagogue.

b. Ointments:

• Containing petrolatum (paraffin) mineral oil.
• Used at bedtime to supplement daytime drops

c. Eyelid sprays

• Contain a liposome-based agent that may stabilize the tear film and reduce evaporation.

d. Artificial tear inserts

• Emplaced once or twice daily offer extended duration of treatment and are preferred by some patients.

e. Mucolytic agents

• Acetylcysteine 5% drops may be useful in patients with corneal filaments and mucous plaques

f. Preservatives

• Can be a potent source of toxicity, especially after punctal occlusion. 
• Numerous non-preserved drops are now available, including some multi-dose products

III. Punctal occlusion: 

• Punctal occlusion reduces drainage and thereby preserves nnatural tears and prolongs the effect of artificial tears. 
• It is of greatest value in patients with moderate to severe  dry eye who have not responded to frequent instillation of topical agents.
• Punctal occlusion are of three types: 
• 1. Temporary occlusion
• 2. Reversible prolonged occlusion
• 3. Permanent occlusion

1. Temporary occlusion

• Can be achieved by inserting collagen plugs into the canaliculi; these dissolve over a number of weeks.
• The main aim is to ensure that epiphora does not occur following permanent occlusion.
• Initially the inferior puncta are occluded and the patient is reviewed after 1 or 2 weeks.
• If the patient is now asymptomatic and without epiphora, the plugs can be removed and the inferior canaliculi permanently occluded (see below).
• In severe kcs both the inferior and superior canaliculi can be plugged.

2. Reversible prolonged occlusion:

• Can be achieved with silicone or long-acting (2–6 months) collagen plugs.
• Problems include extrusion, granuloma formation and distal migration.
• Plugs that pass into the horizontal portion of the canaliculus cannot be visualized and although they can usually be flushed out with saline, if they cause epiphora this is not always possible and surgical retrieval may be needed

3. Permanent occlusion:

• Should be undertaken only in patients with severe dry eye who have had a positive response to temporary plugs without epiphora.
• It should be avoided in patients, especially if young, who may have reversible pathology. All four puncta should not be occluded at the same time.
• Permanent occlusion is performed following punctual dilatation by coagulating the proximal canaliculus with cautery; following successful occlusion, it is important to watch for signs of recanalization.
• Laser cautery seems to be less consistently effective than surgical thermal coagulation.

IV. Anti-inflammatory agents:

• Topical steroids, generally low-intensity preparations such as fluorometholone, are effective supplementary treatment for acute exacerbations. The risks of longer-term treatment must be balanced against the potential benefits in each case.
• Omega fatty acid supplements (e.g. Omega-3 fish oil, flax seed oil) can have a dramatic effect on symptoms and may facilitate the reduction of topical medication.
• Oral tetracyclines for an extended course, often 3 months at a relatively low dose, may control associated blepharitis, especially meibomianitis, and reduce tear levels of inflammatory mediators.
• Topical ciclosporin (usually 0.05%) reduces t-cell mediated inflammation of lacrimal tissue, resulting in an increase in the number of goblet cells and reversal of squamous metaplasia of the conjunctiva.

V. Contact lenses:

• Although contact lens wear can exacerbate dry eye, particularly due to inflammatory, sensory and evaporative effects, these can be outweighed by the reservoir effect of fluid trapped behind the lens, and they are effective at relieving symptoms from secondary corneal changes. 
• Patients should be cautioned regarding the possibility of bacterial keratitis.
• Low water content HEMA lenses:
• Successfully fitted to moderately dry eyes.
• Silicone rubber lenses:
• Contain no water and readily transmit oxygen are effective in protecting the cornea in extreme tear film deficiency.
• Occlusive gas permeable scleral contact lenses:
• Provide a reservoir of saline over the cornea. They can be worn on an extremely dry eye with exposure.

VI. Optimization of environmental humidity:

• Reduction of room temperature to minimize evaporation of tears.
• Room humidifiers 
• Moist chamber goggles or side shields to glasses.

VII. Miscellaneous options:

• Botulinum toxin injection:
• In the orbicularis muscle may help control the blepharospasm that often occurs in severe dry eye.
• Oral cholinergic agonists:
• Reduce the symptoms of dry eye and dry mouth in patients with sjögren syndrome.
• Submandibular gland transplantation:
• For extreme dry eye requires extensive surgery and may produce excessive levels of mucus in the tear film.
• Serum eye drops: 
• Autologous or umbilical cord serum (20–100, they may aid the healing of persistent epithelial defects. Their production and storage carries practical challenges.

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