Lisa M. Nijm

Historical Classification of Blepharitis

Blepharitis represents one of the most common anterior segment disorders encountered in ophthalmology. Data from the National Disease and Therapeutics Index reported 590 000 patient visits in 1982 due to blepharitis.¹ More recent studies have shown that ophthalmologists and optometrists observe blepharitis in 37–47% of their patients.^2,3 Indeed, epidemiologic data from one study in Britain indicated that blepharitis and conjunctivitis account for 71% of ocular cases of inflammation that presented to the emergency room.⁴

Despite the prevalence of blepharitis in both presentation and contribution to ocular conditions, the etiology of blepharitis remains largely unknown. Available evidence suggests that the etiology is most likely multifactorial and this has led to a fair amount of variation in classification of the disease (Table 8.1). Historically, Elsching first described the condition in 1908⁵ and Thygeson classified blepharitis into different types in 1946.⁶ Thygeson initially described the entity as a ‘chronic inflammation of the lid border’ and further divided it into two general categories: squamous and ulcerative. He went on to describe findings associated with seborrheic blepharitis, staphylococcal blepharitis and a combination of the two clinical entities. Thygeson established the association of blepharitis with abnormal Staphylococcus colonization and attributed infection of the meibomian glands to be the primary cause of blepharitis.⁶

Interestingly, over three decades passed before McCulley et al. first reported blepharitis caused by non-infectious means. Studies conducted by McCulley and others revealed that the disease of blepharitis encompassed much more than infection of the meibomian glands.⁷ In fact, one study, comparing 26 control patients to 26 patients with chronic blepharitis, demonstrated that all of the blepharitis patients possessed a generalized sebaceous gland dysfunction, which included the meibomian glands.⁸ Further, investigators of these initial studies noted that stagnation of the meibomian glands seemed to cause a defect in the tear lipid layer, resulting in a superficial punctate keratopathy consistent with tear film deficiency states.⁷ Further investigations led to the notion that the disease of blepharitis encompassed several factors in addition to Staphylococcus aureus that were not of an infectious nature.

Subsequently, McCulley and colleagues designed a more elaborate classification system based on the intense study of changes induced in the lid, lashes, hair follicles, meibomian glands, conjunctiva and cornea in blepharitis patients.⁷ They divided blepharitis into six distinct categories: (1) staphylococcal blepharitis, (2) seborrheic blepharitis, (3) mixed seborrheic and staphylococcal, (4) seborrheic with meibomian seborrhea, (5) seborrheic blepharitis with secondary meibomianitis, and (6) primary meibomianitis.⁴ The authors noted the distinct clinical features of each entity that separated them into different categories. For instance, those patients with staphylococcal blepharitis tended to have relatively more inflammation of the anterior portion of the lid, but for a shorter duration, compared to the other categories. Further more, unlike patients with primary or secondary meibomitis, these patients were culture positive for either S. aureus or S. epidermidis (compared to controls). Strikingly, those patients with seborrheic blepharitis, of any type demonstrated a 95% incidence of associated seborrheic dermatitis, while staphylococcal patients had relatively no dermatologic findings.⁷ This detailed classification and study greatly expanded on the early observations of Thygeson and emphasized the complex nature of the disease.

In 1991, Huber-Spitzy proposed a simplified classification compared to McCulley, consisting of only three groups based on clinical features: (1) blepharitis sicca, (2) blepharitis seborrheica and (3) blepharitis ulcerosa.⁹ The authors described blepharitis sicca as a local eczematous disease, consisting of only superficial inflammation with dry scaling of the lid margin.⁹ On the other hand, blepharitis seborrheica was characterized as having marked inflammation with large ‘greasy scales’ and excessive sebaceous gland secretions. Finally, the most severe form, blepharitis ulcerosa, was diagnosed only when the follicles of the lashes were encrusted with thickly matted, hardened crusts which frequently resulted in bleeding on forceps removal.⁹

Further research detailing the coexistence of blepharitis with dry eye, led Mathers and colleagues to create a multifaceted classification system for blepharitis, ocular surface disease and dry eye, based on cluster analysis of several different variables.¹⁰ In 2004, the investigators presented data suggesting that by assessing meibomian gland dropout, lipid volume, Schirmer test value, evaporation, and lipid viscosity, patients could be placed in one of nine distinct diagnostic groups.⁹ These groups were identified as: (1) obstructive MGD with rosacea and dry eye, (2) obstructive MGD and dry eye, (3) seborrheic MGD, (4) seborrheic MGD with dry eye, (5) seborrheic, obstructive MGD with dry eye, (6) low evaporation and dry eye, (7) high evaporation and high schirmer’s test, (8) low Schirmer’s, high evaporation and dry eye, and (9) normal Schirmer’s high evaporation and dry eye.

In 2003, the American Academy of Ophthalmology advocated the anatomic model of classification that many ophthalmologists were using to divide blepharitis into two main categories, based on anatomic delineation of lid margin: anterior and posterior blepharitis.¹¹ The AAO preferred practice pattern then further subcategorized blepharitis by its presentation, i.e., anterior blepharitis, encompassing both staphylococcal and seborrheic blepharitis and posterior blepharitis, referring mainly to meibomian gland dysfunction.¹¹

More recently, Shapiro and Abelson devised a photographic standardized scale for blepharitis and meibomitis based on anatomical classifications.¹² These anatomical classifications include assessing the lash follicles, dermis, eyelid, vascularity, mucocutaneous junction, meibomian gland orifices and tarsal conjunctiva. Digital images were reviewed by a panel of clinicians and were arranged from least severe to most severe; representative images were then selected to generate a scale of 0 to 3 or 0 to 4 (normal to severe) and subsequently used for several FDA studies.^13,14

Though many detailed classification systems have been proposed, there is no single universally accepted system of classification. Practically, most clinicians continue to classify blepharitis by anatomic location and subcategorize by disease components. Therefore, for purposes of discussion, this chapter will discuss the classification of blepharitis in terms of anterior and posterior lid margin disease and the conditions associated with each entity.

Anterior Blepharitis

Common symptoms of blepharitis include burning, itching, a gritty or foreign body sensation, crusting and redness or irritation of the lid margins. However, there is significant overlap of these symptoms in all forms of blepharitis, and therefore, clinical features must be utilized to distinguish between different etiologies of blepharitis (Table 8.2). Of note, the symptoms of blepharitis are traditionally bilateral and any unilateral presentation, marked asymmetry or resistance to therapy, should alert the clinician to the presence of other diseases masquerading as blepharitis, such as sebaceous cell carcinoma (Fig. 8.1).¹⁵