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Saturday, December 18, 2010

Blepharitis

SIGNS AND SYMPTOMS
Blepharitis is a generic term for several types of eyelid inflammation usually surrounding the lid margin and eyelashes, including both infectious and non-infectious forms. Chronic blepharitis is often linked to an occupation that causes dirty hands, or poor hygiene in general.

The presentation is typically bilateral. Symptoms vary but may include any or all of the following: itching, burning, scratchiness, foreign body sensation, excessive tearing and crusty debris around the eyelashes, especially upon waking. Visible ocular signs include lid erythema, collarettes (a fibrin crust encircling an eyelash), madarosis (missing lashes), trichiasis (an inturned lash), plugged meibomian glands, conjunctival injection and superficial punctate keratitis on the lower third of the cornea. There is often an associated conjunctivitis with papillary hypertrophy of the palpebral conjunctiva.

PATHOPHYSIOLOGY
Though many types of lid inflammation exist, only those that affect lipid secretions are considered blepharitis. The cause is either meibomianitis, seborrhea (excess sebum production), Staphylococcal infection, or some combination of the three.

Excess lipid production by the meibomian glands is the most common form of seborrheic blepharitis, but the condition can also occur from overactive sebaceous glands of the scalp, eyebrows and face as well. The meibomian glands themselves are often inflamed, but not necessarily in all cases.

Paradoxically, this excess oil production ultimately reduces the lipid layer of the tear film. How? The excess quantity of oil on the lid margin promotes the formation of a crusty debris in and around the meibomian glands which eventually clogs the meibomian orifices, or at the very least interferes with meibomian secretions.

These oily deposits on the lid margin provide bacteria with an ideal environment for infestation and multiplication, so it's not surprising that indigenous Staphylococcal infection often accompanies and exacerbates seborrheic blepharitis.

In infectious blepharitis, bacterial exotoxins called lipases break down the cholesterol compounds within the meibomian secretions. This frees fatty acids, which are directly toxic to the corneal epithelium, resulting in punctate epitheliopathy and inflammation. Disturbance to the lipid layer increases tear evaporation and subsequently promotes dry eye.

MANAGEMENT
The mainstay of therapy is improved lid hygiene. This alone may enable you to control symptoms and prevent further complications. Eyelid scrubs using a mild, deodorant-free soap or tearless shampoo will resolve or ameliorate most cases. The treatment dissolves eyelash and skin debris that is often laden with bacteria. Commercially available lid scrubs include Ocu-clear, Lids and Lashes, Lid Wipes SPF and Lid Scrub.

For moderate, severe or chronic cases, you may need to prescribe topical and/or oral medications. When choosing medications, consider these four factors:

the severity of the condition
the effectiveness of the agent
the potential for toxicity reactions
the propensity for allergic reaction

Sulfa drugs (i.e., sulfacetamide) are the classic medications for treating Staphylococcal infection. These work by competitive inhibition of para-amino benzoic acid (PABA), which inhibits cellular processes of the bacteria.

Today, despite a reputation for broad spectrum activity, sulfa-based medications are often ineffective because many organisms have developed resistance to sulfa drugs. In these cases, other acceptable preparations include gentamicin, tobramicin, erythromicin and neomycin, polymyxin B and bacitracin, prescribed BID/QID in either ointment or drop form.

If there's excessive inflammation and/or discomfort, try using an antibiotic-steroid combination prescribed BID or QID, in either ointment or eye drop form. Acceptable choices include:

tobramycin and dexamethasone alcohol (Tobradex)
neomycin or polymyxin B with hydrocortisone (Cortisporin)
neomycin or polymyxin B with dexamethasone (Maxitrol)
sulfacetamide and prednisolone acetate (Blephamide)
sulfacetamide & prednisolone sodium phosphate (Vasocidin)

In recalcitrant cases, try oral tetracycline, 250 to 500mg, BID or QID. While this concentration is not bactericidal, it inhibits the bacterial production of lipases, which increases stability of the tear film.

CLINICAL PEARLS

If, upon digitally expressing clogged meibomian glands, the exudate appears milky white rather than clear, the bacteria have infected the gland itself. This usually warrants oral antibiotic therapy.
Check patients on non-steroidal medications in seven to 10 days, and those using antibiotic-steroid combination within three to five days, for IOP response to the steriod. Follow-up with unmedicated patients every six months or as needed.
Patients with chronic or recurrent history or those who fail to respond to medical therapy may be suffering from acne rosacea. These patients need oral antibiotics and possibly a dermatologic consult.
Rarely, infectious blepharitis occurs from a fungus such as Candida albicans or Aspergillus fumigatus rather than indigenous Staphylococcal bacteria. The distinguishing factor is the presence of granulomas in fungal infection; non-granulomatous infections are bacterial.
Left unattended, chronic blepharitis can spawn degenerative changes in the skin (ulcerative blepharitis), meibomianitis, hordeola, chalazia and marginal sterile keratitis.

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