Exact aetiology of blepharitis is complex and not fully understood, though infection and inflammation contribute to the disease.

Acute blepharitis is commonly due to chemical or allergic drug reaction.

Chronic blepharitis may be associated with exposure to smoke, smog, chemical fumes or any other irritant.

Specific causes of blepharitis include:

-       Dry eye syndrome: Dry eye is reported to be present in staphylococcal blepharitis, and conversely, patients with dry eye develop staphylococcal blepharitis. It is postulated that a decrease in local lysozyme and immunoglobulin levels with tear deficiency may alter resistance to bacteria, thereby predisposing to staphylococcal blepharitis.

 

Some patients with seborrhoeic blepharitis and MGD also develop dry eye. This may result from increased tear evaporation due to deficiency in the superficial lipid layer of tears as well as reduced ocular surface sensation.

-       Acne rosacea.

-       Seborrhoeic dermatitis.

-       Parasitic infestations, such as Demodex folliculorum (causes Demodicosis) and Phthiriasis palpebrarum.

 

Demodex infestation, characterised by cylindrical dandruff like sleeves around eyelashes may be found in patients with chronic blepharitis. Its role is not firmly established since Demodex can be found with nearly same prevalence in asymptomatic patients. However, patients with recalcitrant blepharitis have responded to therapy directed against Demodex mites.

-       Herpes simplex dermatitis.

-       Varicella-zoster dermatitis.

-       Molluscum contagiosum.

-       Allergic or contact dermatitis.

 

Sjögren syndrome may present as blepharitis.

The exact pathogenesis of blepharitis is not known and is suspected to be multi-factorial.

Staphylococcal blepharitis:

The mechanism by which bacteria Staphylococcus aureus cause symptoms of blepharitis is not known. There may be direct irritation from staphylococcal toxins and/or enhanced cell-mediated immunity to bacteria.

Seborrhoeic blepharitis:

Seborrhoeic blepharitis has less inflammation than staphylococcal blepharitis but has more oily or greasy scaling. Some patients of seborrhoeic blepharitis also show meibomian gland dysfunction.

Meibomian gland dysfunction (MGD):

Meibomian gland dysfunction shows abnormalities and altered secretion of meibomian glands. Both altered composition and quantitative deficiency of meibomian gland secretion can contribute to symptoms of blepharitis.

 Diagnosis depends upon the clinical presentation and examination of patient by an eye specialist.

Examination of patients with blepharitis shows findings of associated systemic disease such as:-

-       Acne rosacea: Rosacea is associated with pustules, telangiectasias, rhinophyma or erythema.

-       Seborrhoeic dermatitis: Seborrhoeic dermatitis is characterised by oily skin and flaking from the scalp or eyebrows.

-       Herpes simplex: Herpes simplex may show features of erythema and vesicle formation.

Macroscopic examination of eyelids:

Macroscopic gross examination of eyelids shows erythema and crusting of eyelashes and lid margins.

Slit-lamp examination:

Slit-lamp examination may show features like:-

Eyelid changes:-

-       Madarosis (loss of eyelashes).

-       Poliosis (whitening of the eyelashes).

-       Trichiasis (scarring and misdirection of eyelashes).

-       Plugging and ‘pouting’ of meibomian orifices.

-       Crusting of lashes and meibomian orifices.

-       Ulcers on eyelid margins.

-       Tylosis (lid irregularity).

-       Telangiectasias.

-       Entropion.

Conjunctival changes:-

-       Papillary injection.

-       Loss of normal tarsal vascular architecture.

-       Tarsal thickening.

-       Conjunctival scarring.

-       Cicatricial contraction and distortion of tarsus.

 

Corneal findings:-

-       Punctate epithelial erosions.

-       Marginal infiltrates or ulcers.

-       Limbitis (limbal inflammation and thickening).

-       Peripheral corneal ectasia.

-       Pannus.

-       Phlyctenule formation.

Tear film break-up time (BUT):

This is the interval between last blink and the appearance of first dry spot.

Fluorescein dye is instilled in the eye and patient blinks to spread it and then stops blinking. Eye is examined under cobalt blue filter. After an interval, appearance of black spot or lines, indicate formation of dry areas. Formation of dry area at same spot shows local corneal abnormality and is ignored. A BUT of less than 10 seconds suggests tear film instability.

 

Anterior blepharitis:

Anterior blepharitis involves mainly eyelashes and associated oil glands. Various formations of debris adhere to lashes such as:-

-       Crusting: Crusting refers to flakes of material that adhere to the lashes and usually represents seborrhoeic disease. Seborrhoeic blepharitis primarily involves anterior lid and is associated with formation of greasy crusts adherent to eyelash.

-       Collarette: Collarette is an irregular ring like formation around the base of eyelashes and is seen in staphylococcal blepharitis.

-       Sleeve: Sleeve is a smooth tube of material that also surrounds the base of eyelash as seen in Demodex infestation.

-       Ulcers: Ulcers form at the base of eyelash. These are covered by a crust of fibrin, which is lifted up with the growth of eyelash shaft.

 

Corneal disease is most common with staphylococcal blepharitis.

Posterior blepharitis:

Posterior blepharitis causes alterations in secretory metabolism and function of meibomian glands. Meibomian secretions become wax like causing blockage of gland orifices. Stagnant material causes growth of bacteria and leads to inflammation.

-       Meibomian seborrhoea: Meibomian seborrhoea is characterised by dilated meibomian glands which produce copious amounts of lipids. This appears on lid margins as small oil globules or as collection of waxy material. Tear film is excessively oily and foamy. In severe cases, secretions collect as a frothy discharge at the inner canthus (meibomian foam). This causes burning sensation on first waking in the morning.

 

-       Primary meibomitis: Primary meibomitis is characterised by diffuse inflammation around meibomian gland orifices. It may be associated with acne rosacea or seborrhoeic dermatitis.

 

The meibomian gland orifices may show pouting and be capped by domes of oil (meibomana). Meibomian gland secretions may be turbid and contain particulate debris. Firm pressure on tarsal glands show inspissated secretions.

 

Obliteration of main meibomian ducts may cause secondary cystic dilatation and formation of chalazion (meibomian cyst). In advanced cases, posterior lid margin may show thickening, rounding, vascularisation and notching. There may be secondary changes like papillary conjunctivitis, inferior punctate epitheliopathy and tear film instability.

 

-       Meibomitis with secondary blepharitis: Meibomitis with secondary blepharitis is always associated with seborrhoeic dermatitis. In contrast to primary meibomitis, involvement of meibomian glands is mild and patchy. There is inflammation surrounding the glands and secretions are solidified and are difficult to express. Secondary conjunctival and corneal changes are usually mild. Some patients may have associated tear film instability.

Salient features in general are:-

-       Plugging of meibomian glands.

-       Inspissated lipid secretions.

-       Inflammation of gland orifices.

-       Blockage of orifices may cause chalazion formation or hordeolum due to infection.

-       Tear film instability.

-       Papillary conjunctivitis.

 

Corneal changes can also result from posterior blepharitis.

Diagnostic procedures:-

There are no specific clinical diagnostic tests for blepharitis, however, following tests may be helpful:-

-       Culture from eyelid margins: Culture from eyelid margins may be done for patients with recurrent anterior blepharitis having severe inflammation or who are not responding to treatment.

-       Microscopic evaluation: Microscopic evaluation of eyelashes may reveal Demodex mites.

-       Biopsy: Biopsy from eyelid may be indicated to exclude the possibility of carcinoma in cases showing marked asymmetry or one with unifocal recurrent chalazion not responding to therapy.

Histological findings:

-       Seborrhoeic blepharitis: Seborrhoeic blepharitis shows spongiosis, mild perivascular lymphohistiocytic, mononuclear cellular infiltrates in superficial dermis.

-       Staphylococcal blepharitis: Staphylococcal blepharitis is a chronic non-granulomatous inflammation, usually with neutrophils and often shows acanthosis or parakeratosis.

 

Imaging studies:

-       LipiView (Tear science): LipiView (Tear science) allows visualisation of individual meibomian glands in everted inferior tarsal plate and produces semi-quantitative analysis of meibomian gland viability. This also measures incomplete blink rate and thickness of lipid oil layer.

-       Keratograph 5M (Oculus): Keratograph 5M (Oculus) may be used to obtain images of meibomian glands.

Blepharitis should be differentiated from conditions like:

-       Bacterial infections: Bacterial infections such as impetigo or erysipelas.

-       Viral infections: Viral infections like papillomavirus or vaccinia.

-       Parasitic infections: Parasitic infections e.g. Phthirus pubis (Pediculosis palpebrarum).

-       Dermatoses: Dermatoses such as psoriasis and erythroderma.

-       Immunological conditions: Immunological conditions like atopic dermatitis or contact dermatitis.

-       Benign eyelid tumours: Benign eyelid tumours like actinic keratosis or squamous cell papilloma.

-       Malignant eyelid tumours: Malignant eyelid tumours like basal cell carcinoma or squamous cell carcinoma.

-       Trauma: Trauma may be mechanical, thermal or produced by radiations.

-Toxic conditions: Toxic condition such as medicamentosa (produced by use of medicines).

 

Management should be carried out under medical supervision.

Blepharitis is a chronic condition for which therapy is directed to provide relief in patients who report discomfort or experience visual symptoms.

Pathophysiology of anterior and posterior blepharitis may be different but the treatment options are similar.

General measures:

-       Eyelid hygiene: Eyelid hygiene includes warm compresses, eyelid massage and eyelid scrubs with wet washcloth and no tears baby shampoo, help to clear scales and debris.

Medical therapy:

-       Topical antibiotics: Topical antibiotics are useful to provide symptomatic relief and in eradicating bacteria from eyelid margin.

-       Oral antibiotics: Oral antibiotics are recommended for patients with MGD not controlled with eyelid hygiene or patients with associated rosacea.

-       Topical Steroids: Short courses of topical steroids provide symptomatic relief in cases with significant ocular inflammation.

-       Topical combined antibiotic and steroid: Topical combination of antibiotic and steroid is useful in cases with coexistent bacterial infection and inflammation.

-       Topical artificial tears: Many blepharitis patients have tear film abnormalities. Topical lubrication with artificial tears may improve symptoms when used as an adjunct to eyelid hygiene and medications.

-       Topical cyclosporine: In patients with severe blepharitis, topical cyclosporine improve symptoms superior to combined antibiotic and steroid regimen.

Surgical therapy:

Surgical therapy for blepharitis is required only for complications such as trichiasis, chalazion, ectropion, entropion or corneal disease.

Prognosis:

The prognosis for patients with blepharitis is good to excellent. Blepharitis causes significant morbidity in an extremely small subset of patients. For most, it remains more of a symptomatic affliction rather than a true threat to the health and function.

Blepharitis is a chronic condition and has periods of exacerbation and remissions. Patients experience a considerable amount of discomfort and misery that can greatly reduce their well-being and ability to carry out daily activities of life and work. Symptoms may be frequently improved by management through a prolonged program rather than via an instant cure, but it is difficult to eliminate blepharitis. Rarely, severe blepharitis may result in permanent alterations in eyelid margin.

 Complications of blepharitis may be:

-       Conjunctivitis.

-       Keratitis.

-       Corneal infiltration.

-       Corneal ulcer.

-       Trichiasis.

-       Eyelid notching.

-       Entropion.

-       Ectropion.

Maintenance of long-term regimen of eyelid hygiene helps in prevention of outbreaks and recurrent manifestations of systemic disease.