Infrequent blinking

The most disabling feature of this disorder is hypokinesia (sometimes called bradykinesia or akinesia) — a slowness of voluntary movement and a reduction in automatic movement, such as swinging the arms while walking. The patient s face is relatively immobile (masklike faces), with widened palpebral fissures, infrequent blinking, with certain fixity of facial expression, and a smile that develops and fades slowly. The voice is of low volume (hypophonia) and tends to be poorly modulated. Fine or rapidly alternating movements are impaired, but power is not diminished if time is allowed for it to develop. The handwriting is small, tremulous, and difficult to read. 

In some patients, especially those over age 50 years, a localized or diffuse desquamation of corneal epithelium becomes evident (figure 6-3). This epithelial reaction usually consists of superficial punctate keratitis and probably results from exposure and tear film instability associated with decreased reflex tearing, infrequent blinking, and increased tear evaporation. The punctate keratopathy is frequently absent immediately after anesthetic instillation but may appear 5 to 30 minutes later (Figure 6-4). 

Numerous neurologic and mechanical fectors may result in chronic corneal drying due to infrequent or incomplete blinking or inadequate eyelid closure (lagophthalmos). The resultant irritation to the corneal tissue is known as exposure keratopathy. 

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