Inflammation is the vascular and
cellular response of the tissues to injury (endogenous and exogenous stimuli).
Response to the injury is by production and release of many inflammatory
mediators such as mast cells, lymphocytes, leukocytes, compliment, histamines,
plasma kinins, proteolytic enzymes etc.
Various anti-inflammatory drugs
developed so far have been directed against these inflammatory mediators.
Ophthalmic anti-inflammatory can be broadly classified as corticosteroids,
non-steroidal anti-inflammatory (NSAIDs) and immunosuppressive agents.
CORTICOSTEROIDS; the anti-inflammatory
effects of corticosteroids are non-specific because they inhibit inflammation
without regard to the cause. Their mechanism of action leads to
vasacontriction, stabilization of lysosomal membranes, retardation of
macrophage movement, prevention of kinin release, inhibition of lymphocyte and
neutrophil function, inhibition of prostaglandin synthesis and in prolonged
use. They decrease antibody production. They prevent symblepharon formation
(adhesion of cornea or sclera and the eyelid) and decrease scarring by inhibiting fibroblastic proliferation and
vascularization that usually occurs in chemical and thermal burns.
Corticosteroid is
indicated in the following conditions; Episcleritis and Scleritis, Anterior and
panuveitis, Postoperative eye inflammations, superficial keratitis
(non-specific or punctuate), Traumatic eye inflammations, Corneal injury from
chemical, radiation and thermal burns, Iritis, Cyclitis, Chalazion,
interstitial and disciform keratitis, Vernal and Alergic conjunctivitis,
Blepharitis , Hemangioma, ete.
It should not be used in acute
superficial herpes simplex keratitis, vaccinia, varicella and other viral eye
diseases (cornea and conjunctiva), fungal eye diseases, ocular tuberculosis,
hypersensitivity and after uncomplicated removal of superficial corneal foreign
body. Topical steroids are not effective in sjogrens keratoconjunctivitis and
are only used by pregnant and lactating women potential benefits outweigh
potential hazards.
Many of the steroid preparations
are formulated as suspensions because of their inability to dissolve in a
solution. For topical solutions, instill one to two drops into the lower
conjunctival sac every hour during the day and every two hours during the night
in acute inflammatory conditions of the eye. In mild to moderate inflammations,
instill one drop every four to six hours.
For ointments, apply a thin
coating in the lower conjunctival sac three to four times a day in severe
inflammation. In mild to moderate cases, one application at bed time may be
sufficient to control symptoms.
Ointments are especially convenient when eye
pad is used and may be a preparation of choice when prolonged contact of drug
with ocular tissues is needed.
Examples of ophthalmic
corticosteroids include the following;
- Hydrocortisone: Commercially available as suspensions, solutions and ointments.
- Prednisolone: Commercially available as suspensions, solutions and ointments.
- Dexamethasone: Commercially available as suspensions, solutions and ointments.
- Betamethasone: Commercially available as solutions and ointments.
- Rimexolone: Commercially available as suspensions.
- Triamcinolone: Commercially available as suspensions, ointments and periocular injections.
- Fluorometholone: Commercially available as suspensions and ointments.
- Loteprednol Etabonate: Commercially available as solutions.
- Difluprednate: Commercially available as emulsion.
NON-STEROIDAL ANTI-INFLAMMATORY
DRUGS; In the treatment of ocular inflammation, need of NSAIDs was felt due to
the complications associated with
the more established corticosteroid therapy such as elevation of intraocular
pressure, progression of cataract, increased risk of infection, worsening of
stromal melting etc. hence the use of NSAIDs is safer than the use of
corticosteroid as NSAIDs are relatively free of potential adverse effects of
steroids.
Examples include the following;
- Flurbiprofen: Commercially available as solutions.
- Ibuprofen: Commercially available as solutions.
- Ketorolac : Commercially available as solutions.
- Fenoprofen: Commercially available as solutions.
- Ketoprofen: Commercially available as solutions.
- Naproxen: Commercially available as solutions.
- Piroxican: Commercially available as solutions.
- Indomethacin: Commercially available as solutions and suspensions.
- Diclofenac: Commercially available as solutions.
- Bromfenac: Commercially available as solutions.
- Nepafenac: Commercially available as solutions.
IMMUNOSUPPRESSIVE AGENTS: The
immunosuppressant drugs should be prescribed with caution and preferably in
concert with an oncologist. Patients should be fully informed as to potential
risk and benefits. They are indicated when response to conventional
corticosteroid therapy have filled or when they present unacceptable side
effects. They include the following;
- Cyclophosphamide
- Chlorambucil
- Azathioprine
- Methotrexate
- Cyclosporin
- AInfliximab
They all come in form of oral
tablets or intravenous injections.
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