Dry Eye

Dry Eye (in Facial Palsy)

Individuals with Facial Palsy frequently encounter problems with the affected eye being dry.

This is caused by lack of tear production in the affected eye, causing a dry, possibly painful eye, with risk of corneal ulceration.

In Facial Nerve palsy there are 2 problems which contribute towards making the eye dry:
1. The greater petrosal nerve, derived from the facial nerve, supplies the parasympathetic autonomic component of the lacrimal gland. - controlling production of moisture/tearing in eyes.
2. The zygomatic branch of the Facial Nerve supplies Orbicularis Oculi, and the resulting paralysis causes inability(or reduced ability) to close the eye or blink, so the tears (or indeed artificial lubrication in the form of drops, gel or ointment) are not spread across the cornea properly.

 

The following efffects may be observed:

• The widening of the distance between the upper and lower eyelids, technically described as a "widened palpebral fissure".
• The loss of blink reflex and inability to close the eyelid, due to impaired orbicularis oculi function, can lead to excessive dryness of the cornea, "exposure keratopathy".
• The lower eyelid may turn upwards (a condition known as paralytic eyelid ectropion). When associated with upper and lower lid retraction, this prevents the eyelids from closing to cover the eye completely. (The medical term for this is lagophthalmos).
• Dysfunctional lacrimation (abnormal flow of tears); the overflow of tears onto the face (known as epiphora) being further increased by the absence of lower lid nasal twist – as the nasal twist helps pump tears into the lacrimal drainage system.
  

Symptoms caused by Dry Eye

Symptoms may include:

• Gritty, burning or scratchy feeling in the eye
• Redness of the eye
• Feeling of dryness in the eye
• Pain in the eye
• Blurred vision
• Frequent eye infections
• Corneal damage
• Excessive watering of the eye - confusingly, this can occur for short periods of time in an otherwise dry eye
  

Other factors which can exacerbate Dry Eye

1. Age: Dry occur can occur in the elderly even without any damage to the facial nerve
2. Medical  conditions: Rheumatoid Arthritis, diabetes, Parkinsons's Disease and thyroid problems can all cause Dry Eye syndrome. In addition conditions such as seborrhaeic dermatitis and blepharitis can affect the tear production and exacerbate Dry Eye.
3. Medications: antihypertensives, antihistamines and antidepressants can all reduce tear production.
4. Gender: women can be more susceptible to Dry Eye syndrome due to hormonal changes, eg. at menopause, during pregnancy or when taking oral or injected contraception.

Management of Dry Eye

 It is important to stress to the patient the risks of Dry Eye in Facial Palsy: ie. that it can lead to formation of a corneal ulcer, which in turn can cause loss of vision in the affected eye. Any Facial Palsy patient with an acutely red and sore eye should attend their local Eye Hospital or local A & E as soon as possible.

It is also essential to establish whether the eye is closing fully at night. Often the patient reports that it is, as they are "in the dark" when they close their eyes. But this does NOT mean that they have full eye closure, often they have little or no eye closure but do have a strong "Bell's Phenomenon" where the eyeball rolls upward.

• If they do not have full eye closure then advise them to tape the eye closed overninght, and apply lubrication in the form of Lacri-Lube ointment
• During the day, advise regular use of lubricating drops or gel
• Protect the eye from winds, so when walking outside in windy weather it is helpful to wear wrap-around style sunglasses
• Avoid air conditioning as much as possible (switch of the air-con in the car!) as this dries out the eye