Changes in corneal aesthesiometry and the sub-basal nerve plexus in benign essential blepharospasm

Area of Science:

• Ophthalmology
• Neuroscience
• Sensory Science

Background:

• The underlying causes of blepharospasm are not fully understood.
• The role of the afferent pathway in blepharospasm is suspected but requires further investigation.

Purpose of the Study:

• To investigate the hypothesis that the afferent limb of the blink reflex is abnormal in blepharospasm.
• To assess corneal sensory function using various quantitative measures.

Main Methods:

• A prospective case-control study involving 21 blepharospasm patients and 21 controls.
• Evaluated corneal sensitivity via corneal aesthesiometry and sub-basal nerve morphology using confocal microscopy.
• Utilized questionnaires (Ocular Surface Disease Index) and other tests (tear osmolarity, Schirmer test, tear-film break up time, vital staining, meibomian gland assessment).

Main Results:

• Significantly reduced corneal sensitivity was observed in blepharospasm patients compared to controls (p=0.009).
• A statistically significant reduction in the number of main nerve trunks was found in blepharospasm patients (p=0.04).
• Trends towards lower nerve density, fewer branches, and reduced total nerves were noted in blepharospasm, though not statistically significant.

Conclusions:

• Blepharospasm is linked to diminished corneal sensitivity and a tendency for reduced sub-basal nerve counts.
• Findings suggest impaired corticosensory processing and a potential defect in sensorimotor gating, affecting blink reflex inhibition.