Blepharitis

INTRODUCTION — Blepharitis is a common chronic ophthalmologic condition characterized by inflammation of the eyelid margin associated with eye irritation. Other related eyelid conditions are discussed separately, as is dry eye disease, which is a frequent complication of blepharitis. (See "Eyelid lesions" and "Dry eye disease".)

CLASSIFICATION AND PATHOPHYSIOLOGY — Blepharitis is classified as either posterior or anterior. However, there tends to be considerable overlap of both types, with a predominance of posterior. The etiology and pathophysiology of blepharitis differ somewhat based on the type (posterior versus anterior).

Posterior blepharitis — Posterior blepharitis, the more common type, is characterized by inflammation of the inner portion of the eyelid at the level of the meibomian glands (picture 1) [1]. Meibomian glands are modified sebaceous glands, located within the tarsal plates of the eyelids, responsible for secretion of the oily layer of the tear film (figure 1). This oily layer prevents tear evaporation, reduces the surface tension of the tear layer, and facilitates the spread of tears [2]. It is critical for normal eye lubrication.

Hyperkeratinization of the meibomian gland ductal epithelium is an early finding in patients with posterior blepharitis [3]. Altered lipid composition in gland secretions leads to instability of the tear film [4-10]. The abnormal secretions also have a direct toxic effect on the ocular surface [7,11]. Additionally, the altered lipid composition provides an environment that promotes bacterial growth, which perpetuates the meibomian gland abnormalities. Long-term inflammation leads to gland dysfunction and fibrosis as well as damage to the eyelid and ocular surface.

Anterior blepharitis — Anterior blepharitis is characterized by inflammation at the base of the eyelashes (picture 2). Patients with anterior blepharitis tend to be younger than those with posterior blepharitis [4]. The pathophysiology of anterior blepharitis is not completely understood, although lid-colonizing staphylococcal bacteria appear to play a role in some cases [12]. Anterior blepharitis can be further categorized as staphylococcal or seborrheic type:

●Staphylococcal type is characterized by fibrinous scales and crust around the eyelashes caused by colonization of the eyelids by Staphylococcus aureus and coagulase-negative staphylococci [13-16]. Staphylococci may alter meibomian gland secretion and cause blepharitis via various mechanisms, including direct infection of the lids, production of staphylococcal exotoxin, and provoking an allergic response [11,13-16]. It is likely that a combination of these factors is responsible for the manifestations of anterior blepharitis.

●Seborrheic type is characterized by dandruff-like skin changes and greasy scales around the base of the eyelids [11].

PREDISPOSING CONDITIONS — Several conditions can predispose patients to blepharitis, although it may occur in their absence. These conditions fall into the following categories: inflammatory skin conditions, infections, irritants or allergens, and medications (table 1). Several of these conditions are associated with both posterior and anterior blepharitis:

●Chronic inflammatory skin conditions such as rosacea and seborrheic dermatitis may cause posterior blepharitis [2,17,18]. Other possible causes of both anterior and posterior blepharitis include contact (allergic) dermatitis, eczema, and psoriasis [19]. Blepharitis in patients with such underlying chronic dermatoses tends to be more severe, with increased redness, eyelid swelling, and discomfort. (See "Seborrheic dermatitis in adolescents and adults".)

●Colonization of the eyelids by S. aureus and coagulase-negative staphylococci can cause anterior blepharitis as described above. Chronic colonization may also play a role in posterior blepharitis, although it is less well studied than in anterior blepharitis. The bacteria that comprise the lid and conjunctival flora in posterior blepharitis are the same as those on normal skin but present in greater numbers [14]. They include coagulase-negative staphylococci, Corynebacterium species, and Cutibacterium acnes [4,5,15]. Bacterial lipase produced by colonizing bacteria on the ocular surface may contribute to the differences in lipid composition in the tear film in patients with blepharitis [2,13,16,20].

Demodex folliculorum is a parasite that has been identified in 30 percent of patients with chronic anterior blepharitis but is also found with approximately the same prevalence in asymptomatic persons [21,22]. However, it is clearly a contributing factor in some patients as evidenced by the improvement seen in response to eradicative therapy [22]. A second species, Demodex brevis, has been associated with posterior blepharitis.

●Contact blepharitis is an acute inflammatory reaction of the skin of the eyelids, usually occurring as a reaction to an irritant (eg, cosmetics) [19]. Factors that may provoke or exacerbate blepharitis symptoms include allergic conjunctivitis, cigarette smoking, and contact lens use [23].

●Retinoids (eg, isotretinoin) and chemotherapeutic agents (eg, 5-fluorouracil) may predispose to posterior blepharitis [23].

CLINICAL FINDINGS

Symptoms — Patients with either anterior or posterior blepharitis generally present with chronic recurrent symptoms, which may vary over time, involving both eyes. These include:

●Red, swollen, or itchy eyelids

●Gritty or burning sensation

●“Pink eyes” (see "The red eye: Evaluation and management")

●Excessive tearing (which can paradoxically be a sign of dry eye)

●Crusting or matting of eyelashes in the morning

●Flaking or scaling of the eyelid skin

Advanced cases may also have:

●Light sensitivity

●Blurred vision (transient in nature; usually improves with blinking)

Dry eye disease (picture 3) is a frequent complication of blepharitis, occurring in 25 to 40 percent of patients [24]. (See "Dry eye disease".)

Blepharitis is more common in adults than children, and its prevalence increases with age. However, children can have dramatic episodes of anterior and/or posterior blepharitis, often characterized by more conjunctival and corneal findings than in adults [25,26].

Blepharitis related to Demodex infestation characteristically presents with cylindrical dandruff or “sleeves” on the eyelashes [27].

Contact (allergic) blepharitis from an irritant (eg, cosmetics) manifests with red, swollen, and itchy eyelids occurring acutely after exposure.

Symptoms of an associated chronic inflammatory skin condition may also be noted (eg, facial redness or flushing suggestive of rosacea; itchy and flaking skin involving the scalp, external ear, central face, or trunk suggestive of seborrheic dermatitis). (See "Rosacea: Pathogenesis, clinical features, and diagnosis", section on 'Clinical features' and "Seborrheic dermatitis in adolescents and adults", section on 'Clinical manifestations'.)

Eye examination — The major findings of blepharitis on physical examination include pink or irritated eyelids, which may be associated with crusting.

The eyes should be examined using a slit lamp or, if a slit lamp is not available, a focused light source such as a penlight or otoscope lamp. The eyelids, conjunctivae, tear film, and cornea can be examined more closely with a slit lamp; however, it is generally not necessary to establish the diagnosis.

Eyelids and eyelashes

●The eyelid edges in patients with blepharitis often appear pink or irritated (picture 1 and picture 2). Crusting of the lashes or lid margins may also be visible.

●Patients with anterior blepharitis typically have adherent material around their eyelashes. In the seborrheic variant of anterior blepharitis, there are often greasy-appearing flakes; whereas in the staphylococcal variant, a hard cylindrical crust develops around the eyelash (called a "collarette") [28].

●In posterior blepharitis, it is common to see enlargement of the meibomian gland openings and plugging with thickened, waxy secretions appearing as white or yellow mounds at the gland opening (picture 4).

●The presence of cylindrical dandruff or “sleeves” on the eyelashes can indicate Demodex infection. (See 'Ancillary testing' below.)

●Chronic inflammation can be detected on examination:

The eyelashes should be carefully evaluated as chronic inflammation can lead to trichiasis (misdirected eyelashes), madarosis (loss of lashes), poliosis (loss of pigmentation of lashes), or distichiasis (abnormal growth of eyelashes from meibomian gland orifices). Chronic inflammation can lead to structural changes resulting in entropion (inward turning of eyelid) (picture 5) or ectropion (outward turning of eyelid) (picture 6).

Other findings that are suggestive of chronic inflammation include neovascularization and dilation of blood vessels of the lid margins, thickening of the lid skin, irregularity of the lid contour, and ulcerations along the lid margin. These findings can be observed with a penlight but are more easily appreciated with slit-lamp magnification.

Conjunctivae — Diffuse conjunctival injection is a common but nonspecific finding in patients with blepharitis. Injection may be more prominent on the palpebral conjunctiva [2]. Blepharitis can also be associated with a papillary conjunctival reaction (picture 7), which appears as raised but flat-topped nodules with central vessels.

Tear film — Tear film irregularities are suggested by the presence of debris and/or a foamy appearance on slit-lamp examination. Tear film stability can be formally assessed by measuring the tear break-up time or tear evaporation rate.

Tear break-up time is performed by examining the tear film with a slit lamp using blue light after instilling fluorescein stain in the eye. A healthy tear film appears as a green sheen that remains stable for at least 10 seconds. An abnormal tear film becomes irregular or breaks up in less than 10 seconds.

The tear evaporation rate, which is more often used in research than clinical practice, also assesses the tear film stability and is measured with advanced imaging instruments that use interferometry.

Cornea — Corneal abnormalities are infrequent complications of blepharitis. They are best seen with a slit lamp and may include the following:

●Erosions – Corneal erosions are most commonly found where the inflamed lid margins cross the cornea at the 2, 4, 8, and 10 o'clock positions. Punctate epithelial erosions may appear in the inferior third of the cornea [11]. Similar erosions may be associated with dry eyes, but in that condition they are more commonly distributed throughout the interpalpebral space. (See "Dry eye disease".)

●Infiltrates – Marginal corneal infiltrates may occur as a hypersensitivity reaction to staphylococcal antigens [29]. These appear as an area of superficial whitening near the limbus (border of the cornea and sclera). An area of clear cornea between the limbus and the infiltrate is characteristic.

●Nodules – Corneal nodules (phlyctenules) develop near the limbus and then spread onto the cornea, carrying behind them a leash of vessels. They are considered to be another form of hypersensitivity reaction to staphylococcal antigens [30].

●Ulcers – Rarely, corneal marginal ulcers can develop in the setting of blepharitis. These must be recognized and treated appropriately to avoid progression to corneal perforation.

●Scarring – Chronic irritation and recurrent corneal infiltrates can lead to scarring and development of a superficial corneal pannus (“pseudo-pterygium”) (picture 8).

Ancillary testing — Ancillary testing (eg, bacterial culture, microscopic examination of the eyelash, imaging techniques [meibography]) is not necessary to establish the diagnosis of blepharitis but may have a role in some clinical settings. Culture of the eyelid margins has limited utility because of the difficulty in distinguishing bacterial infection from colonization. However, it may be useful in patients with severe blepharitis and in those who are not responding to empiric therapy [23].

Epilation of the eyelashes for microscopic examination to detect Demodex mites is warranted when the clinical presentation (eg, presence of cylindrical dandruff or “sleeves” on the eyelashes) is suggestive of this diagnosis or when there is severe or refractory blepharitis [23]. It is performed by the ophthalmologist placing the eyelashes on a glass slide and examining under a cover slip after a drop of fluorescein has been added.

Techniques of imaging and measuring the meibomian gland size and function, ocular surface, and tear film dynamics are available and can provide more objective measures of the eyelids and tear function in patients with blepharitis [31-33]. However, these are not routinely used in clinical practice.

DIAGNOSIS — Blepharitis is a clinical diagnosis based on characteristic findings of redness and irritation of the eyelid margin associated with crusting or flakes on the lashes or lid margins (picture 1 and picture 2). It is a bilateral condition but can have asymmetric findings. Slit lamp allows for more detailed examination of the meibomian glands, which can help distinguish between posterior and anterior blepharitis. However, it is generally not necessary to make the diagnosis. (See 'Eye examination' above.)

The diagnosis of blepharitis can be made by the primary care practitioner in most instances. If the diagnosis is unclear based upon clinical findings, referral to an ophthalmologist for slit-lamp examination (if not available in primary care site) is advised. (See 'Indications for referral' below.)

DIFFERENTIAL DIAGNOSIS — Blepharitis can be distinguished from other conditions associated with redness and discomfort of the eyelid based upon the history and physical examination:

●Conjunctivitis – Conjunctivitis, which may be infectious, allergic, or toxic in etiology, is characterized by erythema of eye (rather than eyelids) and the presence of clear or purulent discharge. Vision should be normal, and there should be no evidence of other causes of “red eye” (eg, keratitis, iritis). (See "Conjunctivitis", section on 'Evaluation and diagnosis'.)

●Hordeolum – A hordeolum (stye) is an acute inflammation of an oil gland of the eyelid that presents as a red tender bump on the eyelid (picture 9). It can be associated with blepharitis because abnormal oily secretions block lid glands that may become secondarily infected. Treatment involves application of warm, moist compresses four times a day.

●Chalazion – A chalazion is a firm, non-tender bump on the eyelid that represents a chronic sterile inflammation of an oil gland of the eyelid (picture 10). It results from a granulomatous inflammatory reaction to the lipid content of the blocked lid gland (figure 2) [2]. Treatment involves application of warm, moist compresses four times a day. If the symptoms do not respond after several weeks, incision and curettage or intralesional glucocorticoid injection can be performed.

●Eyelid malignancy – A malignant tumor of the lid skin (sebaceous carcinoma) should be suspected in a patient with persistent unilateral eyelid inflammation (picture 11) [34-37]. Other symptoms of malignancy include a nodular mass, ulceration, extensive scarring, or conjunctival nodules with inflammation [23]. Eyelid malignancy should be considered in patients with unilateral blepharitis that does not respond to treatment. The diagnosis it is confirmed with biopsy. (See "Eyelid lesions", section on 'Sebaceous carcinoma'.)

INDICATIONS FOR REFERRAL — Most patients with blepharitis can be diagnosed and managed by the primary care practitioner. However, referral to an ophthalmologist is warranted if any of the following are present [23]:

●Severe eye redness, pain, or light sensitivity.

●Impaired vision.

●Corneal abnormalities (eg, erosions, ulcers, scarring).

●Uncertain diagnosis or concern for malignancy. (See 'Differential diagnosis' above.)

●Suspicion of Demodex infection. (See 'Ancillary testing' above.)

●Severe or refractory symptoms with poor response to standard management. We define severe symptoms as those affecting vision or quality of life. (See 'Severe or continuing symptoms' below.)

MANAGEMENT

General approach — Patients should be counseled that blepharitis is a chronic condition and many people will require long-term care. Good lid hygiene is the mainstay of treatment for all forms of blepharitis. The goal is to alleviate symptoms and to develop a maintenance regimen to prevent or minimize future exacerbations. Our management approach is based on clinical experience, limited clinical trial and observational data, and consensus expert opinion [38,39]. Our approach is presented in the algorithm (algorithm 1).

All patients should be advised to eliminate or limit potential triggers or exacerbating factors (eg, allergens, cigarette smoking). Contact lenses may continue to be worn if comfortable. Some wearers may benefit from refitting of lenses or the use of a different lens material.

The management of contact (allergic) blepharitis consists of eliminating use of the offending agent (eg, cosmetics). Patients who use cosmetics should be vigilant about removing their makeup at night, cleaning applicators, and avoiding old or expired products.

Mild to moderate symptoms — For patients with mild to moderate symptoms, management consists of warm compresses, lid massage, lid washing, and artificial tears. These patients can generally be managed by the primary care practitioner.

Blepharitis is a chronic condition that requires long-term management. The intensity level of treatment varies based on patient symptoms. Most patients with mild to moderate symptoms respond well to the basic interventions described below. Although it may vary based on the severity of symptoms, in general, these measures should be trialed for approximately six weeks before moving on to other treatments. The efficacy of lid hygiene measures for symptom relief in patients with chronic posterior or anterior blepharitis has been demonstrated in several small clinical trials [38].

Warm compresses — Application of heat to the lids and meibomian glands can liquefy the abnormal solidified secretions by heating them above their melting point. Heat may also promote increased circulation in the meibomian glands and thereby increase the quantity of secretions.

Patients should be advised to soak a wash cloth in warm (not hot) water and place it over the eyes. As the wash cloth cools, it should be rewarmed and replaced for a total of 5 to 10 minutes of soaking time. Warm compresses should be applied two to four times a day as long as the patient has symptoms and at a decreased frequency in the maintenance phase. Numerous eyelid-warming devices are commercially available [40,41]. Such devices are unlikely to be more or less efficacious than using a warm wash cloth, but some patients may prefer them.

Lid massage — Lid massage may help empty the meibomian glands and improve secretion, especially in patients with posterior blepharitis and meibomian gland inspissation. Lid massage should be performed immediately following application of a warm compress, a few times a day. Either the wash cloth that was used for the compress or a clean fingertip should be used to gently massage the edge of the eyelid towards the eye with a gentle circular motion.

Lid washing — Patients with accumulation of debris on the eyelashes may benefit from gentle washing of the eyelid margins following the use of a warm compress. Either warm water or very dilute baby shampoo can be placed on a clean wash cloth, gauze pad, or cotton swab. The patient should then be advised to gently clean along the lashes and lid margin to remove the accumulated material with care to avoid contacting the ocular surface. If shampoo is used, thorough rinsing is recommended. Vigorous washing should be avoided, as it may cause more irritation. Commercially available eyelid scrub solutions are safe and effective and may be preferred for convenience and ease of use [42,43].

Artificial tears — Patients often need to use supplemental artificial tear eye drops to treat the dryness associated with blepharitis (see "Dry eye disease"). Ocular lubrication may also improve contact lens tolerance in patients with blepharitis.

Ineffective therapies — We do not routinely suggest omega-3 fatty acid supplementation for patients with blepharitis. Clinical trials of oral omega-3 fatty acid supplementation for treatment of meibomian gland dysfunction, posterior blepharitis, and dry eye have shown mixed results [44-50]. Most studies have been small and have evaluated surrogate outcomes such as tear break-up time. In the largest trial, there was no apparent benefit [47].

Severe or continuing symptoms

Overview — For patients who do not respond to the symptomatic measures described above and for those with severe symptoms (affecting vision or quality of life), we suggest initiating treatment with topical or oral antibiotic therapy in addition to continuing symptomatic measures. Because of the potential for systemic side effects with oral drugs, topical therapy is usually tried first. Patients with severe or refractory symptoms should be referred to an ophthalmologist for confirmation of the diagnosis and for monitoring during treatment. Other treatment options include topical glucocorticoids and cyclosporine (only to be prescribed by or in consultation with an ophthalmologist).

Topical antibiotics — We suggest topical antibiotic therapy for patients who do not respond to the symptomatic measures described above.

Topical ophthalmic antibiotic ointments (eg, bacitracin, erythromycin) may improve symptoms by reducing the bacterial load of the lashes and conjunctivae. These agents tend to be more effective in anterior blepharitis when the inflammation is more localized to the lash follicles than the meibomian glands; however, as previously described, there is considerable overlap between anterior and posterior blepharitis, and patients with posterior blepharitis may also respond. Both bacitracin and erythromycin have broad spectrum antimicrobial activity and are generally well tolerated. Antibiotic ointment is placed directly onto the lid margin once daily at bedtime for two weeks. Once symptoms improve, treatment can be stopped, but lid hygiene measures should be continued. (See 'Lid washing' above.)

Topical azithromycin ophthalmic solution 1% is an alternative agent particularly for patients with posterior blepharitis. Dosing is one drop twice daily for 10 to 14 days. Azithromycin has been shown to improve meibomian gland secretions and to decrease eyelid redness compared with warm compresses alone [51].

A systematic review of randomized controlled trials and quasi-randomized controlled trials of patients with chronic posterior or anterior blepharitis found that topical antibiotics were effective in providing symptomatic relief and in eradicating bacteria at the lid margin in patients with anterior blepharitis [38]. Additional studies have suggested that antibiotics may have a direct effect on improving meibomian gland function [52,53].

Oral antibiotics after trial of topical antibiotics — Oral antibiotics (eg, doxycycline, tetracycline, azithromycin), are generally reserved for patients with chronic moderate to severe blepharitis that have an inadequate response to topical antibiotic therapy. Treatment is initiated with doxycycline 100 mg or tetracycline 1000 mg daily in divided doses and tapered after improvement (usually two to four weeks) to doxycycline 50 mg or tetracycline 250 to 500 mg once a day. An alternative regimen is azithromycin 500 mg on day 1, followed by 250 mg for four more days.

Evidence supporting the use of oral antibiotics to treat blepharitis is based on mainly observational studies. In a systematic review of eight studies (one randomized trial and seven observational studies) evaluating antibiotic therapy for treatment of posterior blepharitis, all of the included studies documented improvements in ocular surface disease [54]. Most of the studies were small (five included ≤20 patients), and each used a different treatment regimen, including doxycycline, minocycline, or azithromycin. Another systematic review found that the evidence for efficacy of oral antibiotics was inconclusive [38].

Tetracyclines effectively reduce the load of colonizing lid and conjunctival bacteria [55]. They also decrease keratinization and bacterial lipase production [56-58]. Tetracyclines may be especially useful in patients with ocular manifestations of rosacea [59]. In addition, they are associated with reduction of matrix metalloproteinase activity that may play a role in chronic blepharitis [60].

Tetracyclines may cause photosensitization, gastrointestinal side effects, and pseudotumor cerebri, as well as interfere with warfarin and the effectiveness of oral contraceptives. They are contraindicated in pregnant or nursing women and in children under 12 years of age. Azithromycin or other macrolides should be used in these settings. Nausea and other gastrointestinal side effects are common with azithromycin.

Refractory symptoms — Patients with refractory symptoms should be referred to an ophthalmologist.

Topical glucocorticoids — Topical glucocorticoid eyedrops, gels, and ointments are generally reserved for patients with blepharitis that is unresponsive to other therapies [23]. Low-potency agents such as rimexolone, loteprednol etabonate, and fluorometholone are preferred to reduce the risk for adverse effects. Topical glucocorticoids should only be prescribed by or in consultation with an ophthalmologist. Treatment should be limited to two to three weeks to reduce the risk for cataract formation or glaucoma. If topical glucocorticoids are prescribed, patients should be reevaluated in a few weeks to measure intraocular pressure and to determine response to treatment.

Small clinical trials demonstrated short-term improvements in symptom scores, clinical findings (eg, lid margin injection, tear break-up time, meibomian gland expressibility), and tear cytokine levels in patients treated with topical glucocorticoids compared with controls [61,62]. A systematic review concluded that the evidence for the effectiveness of topical glucocorticoids in blepharitis is inconclusive [38].

Topical cyclosporine — Topical cyclosporine should be reserved for patients with blepharitis who do not respond to standard therapies and should be prescribed by an ophthalmologist [23]. It is available as 0.05% eye drops.

Several small prospective studies have demonstrated improvements in objective measures of meibomian gland dysfunction (eg, lid margin injection, tear break-up time, meibomian gland expressibility) in patients treated with topical cyclosporine compared with controls; only one study demonstrated improvement in symptoms [63-65].

The choice between topical glucocorticoids and topical cyclosporine is based on clinician and patient preference. In our experience, topical glucocorticoids tend to be more effective than topical cyclosporine but have greater potential for adverse effects.

Topical cyclosporine is approved by the US Food and Drug Administration (FDA) and European Medicines Agency (EMA) for treatment of dry eyes, but its use in treatment of blepharitis in the absence of dry eye disease is “off-label.” The use of topical cyclosporine in management of dry eyes is discussed separately. (See "Dry eye disease", section on 'Topical cyclosporine'.)

“Off-label” use of topical tacrolimus has also been described. Limited evidence suggests that tacrolimus can improve symptoms and ocular surface status in patients with refractory posterior blepharitis [66].

Demodex infestation — Blepharitis associated with Demodex species infestation can be treated either with oral ivermectin (200 mcg/kg in a single dose and repeated once in one week), topical tea tree oil eyelid scrubs (administered weekly for six weeks) or tea tree shampoo (applied daily for six weeks) [23,67,68]. Demodex infestation is suggested by the presence of cylindrical dandruff or “sleeves” on the eyelashes or by severe or refractory blepharitis. The diagnosis is confirmed by the presence of Demodex mites on microscopic examination. (See 'Ancillary testing' above.)

INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5^th to 6^th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10^th to 12^th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.

Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)

●Basics topics (see "Patient education: Blepharitis (The Basics)" and "Patient education: Stye (The Basics)" and "Patient education: Chalazion (The Basics)")

SUMMARY AND RECOMMENDATIONS

●Classification and pathophysiology – Blepharitis is a common chronic ophthalmologic condition characterized by inflammation of the eyelids associated with eye irritation. The etiology and pathophysiology of blepharitis differ somewhat based on the type (posterior versus anterior) (table 1). However, there is considerable overlap between these categories.

•Posterior blepharitis – Posterior blepharitis, the more common condition, is characterized by inflammation of the inner portion of the eyelid at the level of the meibomian glands (modified sebaceous glands located within the tarsal plates of the eyelids), which are dysfunctional (picture 1). It can be associated with rosacea or seborrheic dermatitis.

•Anterior blepharitis – Anterior blepharitis is characterized by inflammation at the base of the eyelashes (picture 2). It can be associated with staphylococcal colonization or seborrhea. (See 'Classification and pathophysiology' above.)

●Predisposing conditions – Several conditions can predispose patients to blepharitis, although it may occur in their absence. These conditions fall into the following categories: inflammatory skin conditions, infections, irritants or allergens, and medications (table 1). Several of these conditions are associated with both posterior and anterior blepharitis. (See 'Predisposing conditions' above.)

●Clinical features – Patients with blepharitis generally present with symptoms of chronic irritation involving both eyes. These include red, swollen, or itchy eyelids; gritty or burning sensation; “pink eyes”; excessive tearing (which can paradoxically be a sign of dry eye); crusting or matting of eyelashes in the morning; flaking or scaling of the eyelid skin; light sensitivity; and blurred vision (transient in nature, usually improves with blinking). The eyelid edges often appear pink or irritated. Crusting of the lashes or lid margins may also be visible. (See 'Clinical findings' above.)

●Diagnosis – Blepharitis is a clinical diagnosis based on characteristic findings of redness and irritation of the eyelid margin associated with crusting or flakes on the lashes or lid margins (picture 1 and picture 2). Slit lamp allows for more detailed examination of the meibomian glands, which can help distinguish between posterior and anterior blepharitis. However, it is generally not necessary to make the distinction. (See 'Diagnosis' above.)

●Differential diagnosis – The differential diagnosis for blepharitis includes other conditions associated with redness and discomfort of the eyelid such as conjunctivitis, hordeolum (stye), chalazion, and eyelid malignancy. Blepharitis is distinguished from these conditions based upon the history and physical examination. (See 'Differential diagnosis' above.)

●Indications for ophthalmologic referral – Indications for referral to an ophthalmologist include severe eye redness or pain, light sensitivity, impaired vision, corneal abnormalities (eg, erosions, ulcers, scarring), uncertain diagnosis or concern for malignancy, Demodex infection, or severe or refractory symptoms. (See 'Indications for referral' above.)

●General treatment measures – Good lid hygiene is the mainstay of treatment for all forms of blepharitis. In addition, patients should be advised to eliminate or limit potential triggers or exacerbating factors (eg, allergens, cigarette smoking, contact lenses). The goal is to alleviate symptoms and to develop a maintenance regimen to prevent or minimize future exacerbations. Blepharitis is a chronic condition that requires long-term management. The intensity level of treatment varies based on patient symptoms (see 'Management' above). Our approach is presented in the algorithm (algorithm 1):

•Treatment for mild or moderate symptoms – All patients with blepharitis should be advised to use warm compresses, lid massage, and lid washing. This treatment is typically sufficient in patients with mild to moderate symptoms. In addition, patients may benefit from supplemental artificial tear eye drops to treat the dryness associated with blepharitis. Patients whose symptoms do not respond to these measures should be treated with topical antibiotics. (See 'Mild to moderate symptoms' above.)

•Treatment for more severe symptoms or continuing symptoms – Patients who present with more severe symptoms or who do not respond to the symptomatic measures described above should generally be managed by an ophthalmologist. In such patients, we suggest addition of topical antibiotic therapy to symptomatic measures (Grade 2C). Although oral antibiotic therapy is an alternative, topical therapy is usually tried first because of the potential for systemic side effects with oral drugs.

For most patients, antibiotic ointment (eg, bacitracin, erythromycin) is placed directly onto the lid margin once daily at bedtime. Topical azithromycin ophthalmic solution 1% is an alternative agent for patients with predominantly posterior blepharitis. Dosing is one drop twice daily for 10 to 14 days. Once symptoms improve (generally one to two weeks), treatment can be stopped, but lid hygiene measures should be continued.

In patients whose response to topical therapy is inadequate, we suggest switching to oral antibiotic therapy rather than using glucocorticoids or cyclosporine (Grade 2C). Doxycycline, tetracycline, or azithromycin are typically used. (See 'Topical antibiotics' above and 'Oral antibiotics after trial of topical antibiotics' above.)

•Treatment of refractory symptoms – Patients with symptoms refractory to antibiotic therapy can be treated with topical glucocorticoids and cyclosporine. These agents should only be prescribed by or in consultation with an ophthalmologist. (See 'Severe or continuing symptoms' above.)