Most patients with chronic ocular irritation have one of two conditions: dry eye or meibomitis, also known as posterior blepharitis. Dry eye is caused by any condition that decreases tear production or increases tear evaporation sufficiently to result in a loss of water from the tear film and increase tear film osmolarity.1 Tear production can be decreased by lacrimal gland disease or any condition that decreases corneal sensation. Tear evaporation can be increased by large palpebral fissure widths or by meibomian gland dysfunction resulting from meibomitis (Figure 1).

Dry eye patients have bacterial overgrowth on their eyelids, probably due to a decrease in the antibacterial tear proteins lysozyme and lactoferin.2 In tissue culture these bacteria decrease conjunctival goblet cell proliferation, and perhaps more important, just as in patients with primary meibomitis, these bacteria produce esterases and lipases that make the meibomian gland oils pro-inflammatory. This may explain why many aqueous deficient dry eye patients present with meibomitis, with or without meibomian gland dysfunction.3,4

FIGURE 1 Dry eye disease. (Modified from Gilbard JP: Dry-Eye Disorders. In Albert DM, Jakobiec, FA, eds. Principles and Practice of Ophthalmology. Philadelphia, W.B. Saunders, 2000, pp 982-1001.)

Both anterior and posterior blepharitis are characterized by bacterial overgrowth on the lid margins.5 As mentioned, these bacteria produce lipases and esterases that hydrolyze meibomian oils, making them pro-inflammatory.6,7 In the most common type of anterior blepharitis the bacterial overgrowth causes inflammation at the base of the lashes. In posterior blepharitis bacterial overgrowth cause an inflammatory process centered around the meibomian glands. This inflammatory process can spread throughout the lid margin and spill over to involve the ocular surface. Inflammation involving the meibomian gland leads to vascularization and fibrosis, causing stenosis and then closure of the meibomian gland orifices, resulting in dysfunction of the meibomian glands.9

There are two forms of blepharitis that are not bacterial. Seborrheic blepharitis is due to overgrowth of Malassezia ovale, a lipophilic yeast that in older works is called Pityrosporum ovale,8  and Demodex blepharitis is characterized by collarettes at the base of the eyelashes.
           

Differentiating Dry Eye and Meibomitis by History
Dry eye patients typically complain of a sandy-gritty feeling in their eyes or a burning sensation that becomes worse as the day progresses. At night the closed eyelids form a watertight seal blocking evaporation, and the ocular surface has a chance to recover. With eye opening, evaporation begins, and as the day progresses evaporation outstrips tear production and tear film osmolarity increases. Thus, the symptoms increase as the day proceeds.10 Initially patients may complain of an increased awareness of their eyes. As the cornea becomes involved, patients may develop light sensitivity.

Meibomitis patients also complain of chronic sandy-gritty irritation or burning in their eyes, but the symptoms are worse upon eye opening in the morning. At night, the inflamed eyelids remain tight against the cornea, tear secretion decreases, and inflammatory mediators have time to build up and irritate the ocular surface. As an inflammatory condition, patients may also have redness of their eyes upon eye opening in the morning.

FIGURE 2 Appearance of the meibomian glands in health and disease. (Modified from Gilbard JP: Dry-Eye Disorders. In Albert DM, Jakobiec, FA, eds. Principles and Practice of Ophthalmology. Philadelphia, W.B. Saunders, 2000, pp 982-1001.)

Meibomian gland inflammation causes gland damage, and dysfunction develops, including meibomian orifice stenosis and, later, closure (Figure 2). Deprived of the lipids that inhibit evaporation, tear film evaporation then increases, and these patients develop a second symptom peak from increased tear film osmolarity late in the day. With time, the meibomian gland architecture is destroyed. At that point, patients’ early morning symptoms will resolve, but the evaporative dry eye symptoms that get worse later in the day will persist.

Differentiating Dry Eye and Meibomitis by Examination
The dry eye diagnosis can usually be made from the patient history, and the exam permits a determination of the cause(s). Patients with dry eye may appear normal on examination; the first changes can be best detected by painting a wetted fluorescein strip across the inferior tarsal conjunctiva and having the patient blink. As tear production decreases, the nasal inferior marginal tear strip will not fluoresce. With further decreases, the entire tear film will not fluoresce, and later the tear film will appear more viscous in quality, with debris.

Acne rosacea is often associated with meibomitis, but patients may exhibit only facial telangiectasias with no central facial flushing. Meibomitis patients have lid margin telangiectasis and, later, stenosis or closure of meibomian gland orifices, thickening of the meibomian gland secretions, and first bloating, then distortion, and finally obliteration of the normal subconjunctival meibomian piano key pattern.

Both dry eye and meibomitis may cause ocular surface staining. Dry eye staining, if seen, is limited to the interpalpebral fissure, the nasal conjunctiva typically staining more than the temporal (except in very dry patients where staining can be equivalent), and the cornea stains inferiorly and less than the conjunctiva. Meibomitis staining, if seen, may extend outside the interpalpebral zone and affect the cornea as much as the conjunctiva. There is normal tear film fluorescence in meibomitis, and as oil production decreases, the tear film takes on a watery appearance.

Treatment Tools for Blepharitis
Anterior Blepharitis For anterior blepharitis, bacterial overgrowth on the outer eyelids needs to be controlled. Previously, lid cleansing with diluted baby shampoo was recommended, but drying of the delicate eyelid skin and inability to affect bacteria has led to specialized lid hygiene products. The ideal eyelid cleanser is rapid acting and effective against both gram negative and gram positive bacteria. One product, SteriLid® Foaming Eyelid Cleanser (Advanced Vision Research), contains linalool and provides at least a one log reduction in common eyelid pathogens, including Staphylococcus aureus and methicillin resistant S. aureus (MRSA), in 60 seconds. This rapid action allows for increased patient compliance, and I believe that SteriLid’s antibacterial action makes it useful for both blepharitis and dry eye patients.

Posterior Blepharitis For posterior blepharitis, bacterial overgrowth surrounding the meibomian glands needs to be controlled, inflammation suppressed, and meibomian gland oil thinned. At diagnosis, patients with mild meibomitis (ie, signs but no symptoms) should be started on a topical eyelid cleanser (eg, SteriLid) to control bacterial overgrowth and an oral flaxseed oil and fish oil omega-3 supplement plus warm compresses to thin meibomian gland oils and suppress inflammation. 

Clinical experience and pilot studies have suggested that TheraTears Nutrition (an omega-3 supplement with flaxseed oil and fish oil) is useful in the treatment of dry eye and meibomitis, as well as dry mouth.11,12 The omega-3 free fatty acids from flaxseed oil appear to thin meibomian gland oils and improve the lipid layer of the tear film, while the fish oil suppresses inflammation. The blend of these two oils in TheraTears Nutrition have been shown to increase salivary gland secretion, and we believe it increases tear production by the same mechanism of action.11,12

Warm compresses thin meibomian glands oils, thicken the tear film lipid layer, and have been shown to decrease tear film evaporation, improve tear film break-up time, decrease ocular surface staining, and improve dry eye symptoms.13,14 Compresses should be applied in the morning, and, ideally, in the early afternoon as well to prevent dry eye symptoms in the late afternoon. This can be done with a washcloth warmed by hot water, or by an easier and more pleasant-to-use waterless and portable system (iHeat® warm compress system; Advanced Vision Research) that promotes compliance.

For patients with symptomatic posterior blepharitis, oral doxycycline is recommended along with TheraTears Nutrition and warm compresses. Doxycycline, 50 to 100 mg per day, suppresses lid inflammation and decreases bacterial overgrowth.

A new prescription kit (Nutridox® Convenience Kit; Advanced Vision Research) provides a 1-month supply of Doxycycline, 75 mg/day, TheraTears Nutrition, 3 softgels/day, and a starter supply of warming units for the iHeat warm compress system. For severe meibomitis, the doxycycline is continued for 1 to 3 months. If the patient’s early morning symptoms have resolved, the doxycycline can be stopped and the patient continued long-term on TheraTears Nutrition, SteriLid, to replace the anti-bacterial action of doxycycline, and warm compresses.