Medical Management of Dry Eye Disease-Identify and Treat Associated Conditions
Local Factors Associated with Dry Eye
These factors include: (i) Posterior lid margin disease (blepharitis) may exacerbate evaporative dry eye. This may be associated with rosacea and aller¬gic eye disease. (ii) Corneal exposure from lagophthalmos, lid margin defects, or seventh nerve palsy allows excessive evaporation. Abnormal globe position, lid retraction or exophthalmos from thyroid eye disease should be treated. (iii) Relative corneal anaesthesia with reduced reflex tearing following LASIK may precipitate dry eye symptoms.
Systemic Disease
A number of systemic conditions also cause ocular surface disease and severe dry eye, although dry eye disease is rarely the presenting symptom. These conditions should be investigated and treated appropriately, but the treatment of the associated dry eye disease is then usually still based on ocular signs rather than the underlying condition. These diseases include: (i) Sjogren's syn¬drome; (ii) rheumatoid arthritis; (iii) scleroderma (crest syndrome - calcinosis,
Reynaud's phenomenon, oesophageal hypomotility, sclerodactyly, and telang-iectasia); (iv) systemic lupus erythematosis; (v) retroviral infection: infection with HTLV1, HIV, hepatitis C, or chronic Epstein-Barr virus (EBV) infection - EBV infection has been proposed as a trigger for the onset of Sjogren's syn¬drome, and (vi) cicatricial conjunctivitis (mucous membrane pemphigoid, Stevens-Johnson syndrome, atopic keratoconjunctivitis, graft-versus-host disease).
Tear Substitutes
These have a relatively simple formulation compared to normal tears and their delivery is periodic rather than continuous. Although continuous delivery pumps are available, they are usually restricted to the treatment of extreme dry eye. The relative contribution of their individual components to the overall desired effect - lubrication, replacing tear components, reducing osmolarity, or diluting inflammatory agents - is difficult to prove. Slightly alkaline pH drops are better tolerated than neutral or acidic drops . Almost all artificial tears aim to replace the aqueous phase of the tear film. There are no mucus substi¬tutes, and oils and lipids are only an approximation to the action of tear lipid layer. Simple electrolyte solutions and saline are rapidly lost from the ocular surface and attempts have therefore been made to increase the ocular surface residence time by adding macromolecules that increase the viscosity or gel properties of the solution, contribute a demulcent effect, and potentially com¬bine with the mucus component of the tear film . These viscous or gel agents are otherwise inactive components of the drop. For example, the ocular surface residence time of arboxymethylcellulose is significantly longer than smaller molecule hydroxypropylmethylcellulose, although it is uncertain whether this fact fully explains the difference in effect. Because relative effi¬cacy or artificial tear drops is difficult to compare the principal categories are listed in alphabetical order .
(1)Acetylcysteine 5% drops are commercially available and are useful in patients with filamentary keratitis and mucous plaques secondary to dry eye. They are used 4 times daily and may cause stinging following instillation if there is epithelial disease. Acetylcysteine 10 and 20% is not available commer¬cially and they have a limited bottle life even if kept refrigerated.
(2)Cellulose-based products have been the mainstay of artificial drop treatment for years. Except for carmellose they have a short ocular surface res-idence time.
(3)Carbomers 974P and 980 make a relatively viscous solution, which increases ocular residence time.
Local Factors Associated with Dry Eye
These factors include: (i) Posterior lid margin disease (blepharitis) may exacerbate evaporative dry eye. This may be associated with rosacea and aller¬gic eye disease. (ii) Corneal exposure from lagophthalmos, lid margin defects, or seventh nerve palsy allows excessive evaporation. Abnormal globe position, lid retraction or exophthalmos from thyroid eye disease should be treated. (iii) Relative corneal anaesthesia with reduced reflex tearing following LASIK may precipitate dry eye symptoms.
Systemic Disease
A number of systemic conditions also cause ocular surface disease and severe dry eye, although dry eye disease is rarely the presenting symptom. These conditions should be investigated and treated appropriately, but the treatment of the associated dry eye disease is then usually still based on ocular signs rather than the underlying condition. These diseases include: (i) Sjogren's syn¬drome; (ii) rheumatoid arthritis; (iii) scleroderma (crest syndrome - calcinosis,
Reynaud's phenomenon, oesophageal hypomotility, sclerodactyly, and telang-iectasia); (iv) systemic lupus erythematosis; (v) retroviral infection: infection with HTLV1, HIV, hepatitis C, or chronic Epstein-Barr virus (EBV) infection - EBV infection has been proposed as a trigger for the onset of Sjogren's syn¬drome, and (vi) cicatricial conjunctivitis (mucous membrane pemphigoid, Stevens-Johnson syndrome, atopic keratoconjunctivitis, graft-versus-host disease).
Tear Substitutes
These have a relatively simple formulation compared to normal tears and their delivery is periodic rather than continuous. Although continuous delivery pumps are available, they are usually restricted to the treatment of extreme dry eye. The relative contribution of their individual components to the overall desired effect - lubrication, replacing tear components, reducing osmolarity, or diluting inflammatory agents - is difficult to prove. Slightly alkaline pH drops are better tolerated than neutral or acidic drops . Almost all artificial tears aim to replace the aqueous phase of the tear film. There are no mucus substi¬tutes, and oils and lipids are only an approximation to the action of tear lipid layer. Simple electrolyte solutions and saline are rapidly lost from the ocular surface and attempts have therefore been made to increase the ocular surface residence time by adding macromolecules that increase the viscosity or gel properties of the solution, contribute a demulcent effect, and potentially com¬bine with the mucus component of the tear film . These viscous or gel agents are otherwise inactive components of the drop. For example, the ocular surface residence time of arboxymethylcellulose is significantly longer than smaller molecule hydroxypropylmethylcellulose, although it is uncertain whether this fact fully explains the difference in effect. Because relative effi¬cacy or artificial tear drops is difficult to compare the principal categories are listed in alphabetical order .
(1)Acetylcysteine 5% drops are commercially available and are useful in patients with filamentary keratitis and mucous plaques secondary to dry eye. They are used 4 times daily and may cause stinging following instillation if there is epithelial disease. Acetylcysteine 10 and 20% is not available commer¬cially and they have a limited bottle life even if kept refrigerated.
(2)Cellulose-based products have been the mainstay of artificial drop treatment for years. Except for carmellose they have a short ocular surface res-idence time.
(3)Carbomers 974P and 980 make a relatively viscous solution, which increases ocular residence time.
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