aqueous tear evaporation rate; however, average tear production and tear volume increased. Therefore, the mechanism of action of omega-3 supplementation for MGD is not yet established.
Treatment with systemic tetracyclines can be very effective. Because tetracycline must be taken on an empty stomach and requires more frequent dosing, doxycycline and minocycline are now used with increasing frequency. The dosages of doxycycline and minocycline are 100 mg and 50 mg, respectively, every 12 hours for 3–4 weeks, tapering to 40–100 mg per day, based on clinical response. Lower doses may be equally effective. It often takes 3–4 weeks to achieve a clinical response. Therapy must often be continued long-term. Erythromycin can be used as alternative therapy in patients with known hypersensitivity to tetracycline or in children. Patients with MGD should be informed that therapy may control but not eliminate their condition.
Adverse effects of systemic tetracyclines include photosensitization, gastrointestinal upset, and, in rare instances, azotemia. Long-term use may lead to oral or vaginal candidiasis in susceptible patients. The use of tetracyclines is contraindicated during pregnancy, in women who are breastfeeding, and in patients with a known hypersensitivity to these agents. These agents should be used with caution in women of childbearing age, women with a family history of breast cancer, patients with a history of liver disease, and patients taking certain anticoagulants (eg, warfarin). Tetracyclines may also reduce the efficacy of oral contraceptives. These antibiotics should also be avoided in children younger than 8 years because they cause permanent discoloration in teeth and bones in this population.
Recently, several new therapies have been proposed for MGD. A commercially available system combines gentle pulsatile pressure and thermal energy to increase blood flow to the eyelid and open obstructed meibomian gland ductules. It is also possible to use special instruments designed to probe and open the meibomian glands mechanically.
American Academy of Ophthalmology Cornea/External Disease Panel. Preferred Practice Pattern Guidelines. Blepharitis. San Francisco: American Academy of Ophthalmology; 2011. Available at: www.aao.org/ppp.
Blackie CA, Korb DR, Knop E, Bedi R, Knop N, Holland EJ. Nonobvious obstructive meibomian gland dysfunction. Cornea. 2010;29(12):1333–1345.
Macsai MS. The role of omega-3 dietary supplementation in blepharitis and meibomian gland dysfunction. Trans Am Ophthalmol Soc. 2008;106:336–356.
Wojtowicz JC, Butovich I, Uchiyama E, Aronowicz J, Agee S, McCulley JP. Pilot prospective, randomized, double-masked placebo-controlled clinical trial of an omega-3 supplement for dry eye. Cornea. 2011;30(3):308–314.
Other Eyelid Diseases Associated With Ocular Surface
Disorders
Rosacea
PATHOGENESIS Rosacea (sometimes called acne rosacea) is a chronic acneiform disorder that can affect both the skin and eyes. This disease has no proven cause; however, it may be related to the overexpression of cathelicidin antimicrobial peptides. Cathelicidins cause neutrophil recruitment, angiogenesis, and cytokine release, which may contribute to the inflammatory skin changes seen in patients with rosacea. It is associated with cutaneous sebaceous gland dysfunction of the face, neck, and shoulders. Although rosacea has generally been thought to be more common in fair-skinned individuals, it may simply be more difficult to diagnose in people with dark skin. It is important to look for the sometimes subtle clinical findings by external examination under bright room light. Although alcohol can contribute to a worsening of this disorder because of its effect on vasomotor
stability, most patients with rosacea do not have a history of excessive alcohol intake.
CLINICAL PRESENTATION A skin condition that frequently involves the eyes, rosacea is characterized by excessive sebum secretion with frequently recalcitrant chronic blepharitis. Eyelid margin telangiectasia is very common, as are meibomian gland distortion, disruption, and dysfunction, which can lead to recurrent chalazia. Ocular involvement can also progress, leading to chronic conjunctivitis, marginal corneal infiltrates (Fig 3-14), sterile ulceration, episcleritis, or iridocyclitis. If properly treated, these lesions can resolve with few sequelae. Repeated bouts of ocular surface inflammation can cause corneal neovascularization and scarring (Fig 3-15).
Figure 3-14 Marginal keratitis associated with rosacea.
Figure 3-15 Rosacea with chronic superficial keratopathy and corneal neovascularization.
This disorder is generally found in patients aged 30–60 years, with a slight female preponderance. However, ocular rosacea can be encountered in younger patients and is often underdiagnosed. Facial lesions consist of telangiectasias, recurrent papules and pustules, and midfacial erythema (Fig 3-16). Rosacea is characterized by a malar rash with unpredictable flushing episodes, which are sometimes associated with the consumption of alcohol, coffee, or other foods. Rhinophyma, thickening of the skin and connective tissue of the nose, is a characteristic and obvious sign associated with this disorder, but such hypertrophic cutaneous changes occur relatively late in the disease process.
