Blepharitis

Introduction

Blepharitis is inflammation of the eyelids, and is commonly seen in general practice.

It occurs more commonly in dogs than cats, but can also occur in horses and small mammals such as rabbits.

The owner will report eye irritation and a discharge may be present. The condition is most likely to be insidious in onset and gradually progressive, although acute presentations do occur.

There are many underlying causes for blepharitis, and it can occur along with conjunctival hyperaemia. The most common cause is bacterial infection of the eyelids, most often with Staphylococcal species, followed by an inappropriate allergic or sensitivity reaction to the bacterial toxins.

In dogs, blepharitis can also be caused by fungi such as the ringworm species and Aspergillus. Dermatological conditions such as atopy, Leishmania or puppy strangles can also be responsible.

In horses, primary bacterial infection is rare, and more common causes include trauma, allergic reactions to insect bites, exposure to intense solar radiation, ringworm and cutaneous habronemiasis.

In rabbits, bacterial blepharitis is the most common cause, but Treponema cuniculi and myxomatosis infections can also lead to the condition.

Clinical Signs

Many forms of blepharitis are part of a general dermatological condition, and so skin changes are common.

Ophthalmic examination will reveal eyelid swelling and hyperaemia, possibly with crusting or exudative erosions close to the eyelid margins. Some lesions are erosive and a serosanguinous discharge may be present.

Periorbital hyperaemia and alopecia may be signs of self-trauma.

Conjunctival hyperaemia will accompany most cases of blepharitis, and corneal ulceration may develop.

Normally there is no intraocular involvement with blepharitis, but if uveitis is present this may suggest either the uveodermatological syndrome, or Leishmania infection.

Diagnosis

Swabs for bacterial culture and sensitivity should be taken from the ocular discharge and the lid margins themselves. The contents of the meibomian glands at the eyelid margins can be expressed for sampling.

Impression smears of the lid margins can be useful, as can hair plucks and scrapes to look for parasites.

If Leishmania is suspected, serological testing should be performed.

Biopsy may be considered if a more generalised condition is suspected, and the sample should include the eyelid margin wherever possible.

Treatment

The specific treatment regime will depend upon the underlying aetiology for the blepharitis.

General hygiene and preventing self-trauma will apply to all cases.

For a primary bacterial blepharitis, broad-spectrum systemic antibiotics for 2-4 weeks are advised. Eyelids are part of the skin and require systemic medication.

A topical lubricant can be considered as involvement of the meibomian glands will affect the lipid layer of the tear film and there will be increased evaporation, leading to qualitative tear film abnormalities.

If inflammation is particularly severe, an anti-inflammatory such as a NSAIDs can be administered systemically. If an immune-mediated condition is suspected, systemic steroids can be administered at immuno-suppressive levels until signs resolve.

Blepharitis Learning Resources
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References

Slatter, D. (2001) Fundamentals of veterinary ophthalmology Elsevier Health Sciences

Gelatt, K. (2000) Essentials of veterinary ophthalmology Wiley-Blackwell

Turner, S. (2008) Small animal ophthalmology Elsevier Health Sciences

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