Staphylococcal blepharitis is seen more commonly in younger individuals. Symptoms include burning, itching, foreign-body sensation, and crusting, particularly upon awakening. Symptoms of irritation and burning tend to peak in the morning and improve as the day progresses, presumably as the crusted material that accumulates on the eyelid margin overnight is liberated.
Typical clinical manifestations include hard, brittle fibrinous scales and hard, matted crusts surrounding individual cilia (collarettes) on the anterior eyelid margin (Fig 3-18B). Small ulcers of the anterior eyelid margin may be seen when the hard crusts are removed (see Fig 3-17). Injection and telangiectasis of the anterior and posterior eyelid margins, white lashes (poliosis), lash loss (madarosis), and trichiasis may be seen in varying degrees, depending on the severity and duration of the blepharitis.
Staphylococcal blepharoconjunctivitis may present as a chronic (>4-week duration) unilateral or bilateral conjunctivitis. Clinical findings include a papillary reaction of the tarsal conjunctiva, particularly the inferior tarsal conjunctiva near the eyelid margin, as well as injection of the bulbar and tarsal conjunctivae. Conjunctival injection is mild and mucopurulent discharge scant. Concomitant ATD and/or lipid-induced tear film instability may also occur. If unilateral signs or symptoms persist, the clinician should consider obstruction of the nasolacrimal system and perform a dye disappearance test or perhaps irrigation of the nasolacrimal system.
Specific clinical signs in patients with chronic conjunctivitis may implicate certain bacterial species. Staphylococcus aureus is often associated with matted, honey-colored crusts and ulcers on the anterior eyelid margin, inferior punctate keratopathy, marginal corneal infiltrates, and, in rare cases, conjunctival or corneal phlyctenules. Moraxella lacunata may cause a chronic angular blepharoconjunctivitis, with crusting and ulceration of the skin in the lateral canthal angle and a papillary or follicular reaction on the tarsal conjunctiva, sometimes with adjacent keratitis. Moraxella angular blepharoconjunctivitis is frequently associated with concomitant S aureus blepharoconjunctivitis.
Several forms of keratitis may develop in association with staphylococcal blepharoconjunctivitis. Punctate epithelial keratopathy manifests as erosions that stain with fluorescein; these erosions are often distributed across the inferior cornea, coinciding with the contour of the eyelids across the corneal surface. A diffuse pattern may also be observed, and asymmetric or unilateral keratopathy is not uncommon. The degree of corneal involvement can be markedly disproportionate to the severity of the eyelid disease, a circumstance that can lead to diagnostic confusion. Marginal corneal infiltrates may be the most distinctive clinical finding, with creamy white elliptical opacities typically separated from the limbus by a relatively lucent zone. They most often occur near the point of intersection of the eyelid margin and the limbus, that is, at 10, 2, 4 and 8 o’clock (Fig 3-19; also see Fig 3-15A).
Figure 3-19 Staphyloccocal marginal corneal infiltrates are typically oval, white opacities; usually, there is a clear zone between the lesions and the limbus.
(Courtesy of David Rootman, MD.)
Phlyctenulosis is a local corneal and/or conjunctival inflammation that is believed to represent a cell-mediated, or delayed, hypersensitivity response induced by microbial antigens such as the cell wall components of staphylococcus. Phlyctenulosis is frequently associated with S aureus in developed countries and is classically associated with Mycobacterium tuberculosis infection affecting malnourished children in tuberculosis-endemic areas of the world.
Phlyctenules are hyperemic, focal nodules consisting of chronic inflammatory cells. They often present unilaterally at or near the limbus, on the bulbar conjunctiva or cornea, as small, round, elevated, gray or yellow nodules accompanied by a zone of engorged hyperemic vessels (Fig 3-20A). Phlyctenules typically become necrotic and ulcerate centrally; they then spontaneously involute over a period of 2–3 weeks. Conjunctival phlyctenules do not lead to scarring, but residual wedge-shaped fibrovascular corneal scars form along the limbus; when such scars are bilateral and inferior, they may suggest previous phlyctenulosis. Corneal involvement is recurrent, and centripetal migration of successive inflammatory lesions may eventually occur, affecting vision if untreated (Fig 3-20B). Occasionally, such inflammation leads to corneal thinning and, in rare cases, perforation.
Eyelid and conjunctival cultures can be performed in suspected cases of staphylococcal blepharoconjunctivitis when the initial diagnosis is in doubt, the treatment response is poor, or the infection is worsening. An antibiotic washout period of at least a week should be employed prior to culture. In chronic unilateral conjunctivitis refractory to therapy, conjunctival malignancy (eg, sebaceous cell carcinoma) and factitious illness should be ruled out.
The characteristic laboratory finding in staphylococcal blepharoconjunctivitis is a heavy, confluent growth of S aureus. Nevertheless, the finding of a light to moderate growth of bacteria and/or the isolation of staphylococcal species other than S aureus does not exclude the diagnosis, particularly if a predominant manifestation of the disease is punctate epithelial keratopathy, marginal infiltrates, or phlyctenulosis. Susceptibility testing may be useful in guiding treatment in cases that have been refractory to empiric antibiotic therapy.
Figure 3-20 Phlyctenule. A, Confluent phlyctenules secondary to staphylococcal blepharitis. B, Recurrent phlyctenular involvement may result in fibrovascular scarring that progresses across the cornea and into the visual axis.
(Part B courtesy of Robert S. Feder, MD.)
Effective treatment addresses both the infection and the associated inflammation. Eyelid hygiene, with either commercially available eyelid scrub kits or warm water mixed with baby shampoo, may help reduce bacterial colonization and the accumulation of sebaceous secretions. With these treatments, patients should focus their attention on the base of the lashes, where colonization and seborrhea are the greatest. Aggressive scrubbing should be discouraged. Topical bacitracin, erythromycin, azithromycin, or tobramycin may be applied to the eyelid margin to reduce both the bacterial load and associated inflammation. As stated earlier, ATD and/or lipid-induced tear film instability may occur concomitantly; these should be treated to improve patient comfort. Because many strains of bacteria have developed resistance to sulfa drugs, these antibiotics are less efficacious in the treatment of staphylococcal blepharitis.
In selected cases, anti-inflammatory therapy consists of limited use of mild doses of topical corticosteroids. Phlyctenulosis and staphylococcal marginal keratitis readily respond to judicious use of topical steroids used in concert with antibiotic therapy and eyelid hygiene. If epithelial defects are noted over the infiltrates, diagnostic cultures should be considered before corticosteroid treatment is begun. Long-term or indiscriminate use of corticosteroids should always be avoided.
Patients with routine staphylococcal blepharitis or blepharoconjunctivitis obtain more rapid symptomatic relief with adjunct topical corticosteroids; however, punctate epithelial keratopathy related to drug toxicity is unlikely to respond. The long-term use of topical corticosteroids should be weighed against the risk of adverse effects and, less likely, further proliferation of the pathogen.
Excerpted from BCSC 2020-2021 series: Section 10 - Glaucoma. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.