Neurostimulation device presents a new approach to dry eye disease
Nasal neurostimulation could be a promising new approach for the management of dry eye disease, suggest the results of an early clinical study presented at the 2016 ASCRS•ASOA Symposium & Congress in New Orleans, USA.
Tear secretion is regulated by a complex of factors known as the lacrimal function unit. Sensory stimulation of the ocular surface initiates a sensory autonomic reflex that results in tear secretion. Afferent nerves in the nose contribute to the process, stimulating reflex tearing, explained Stephen C Pflugfelder MD, Baylor College of Medicine, Houston, Texas, USA.
The lacrimal glands produce fluid and tear proteins, and the conjunctival goblet cells secrete gel forming soluble mucins that coat the ocular surface. Neural signalling of tear secretion may be interrupted by a variety of mechanisms. These include decreased corneal sensitivity, nerve damage, anticholinergic medications, and a variety of inflammatory cytokines.
“The Oculeve neurostimulator takes advantage of these neurostimulatory pathways. Developed at Stanford University (California, USA), the device delivers a titratable intranasal electrical stimulus to stimulate tear secretion. This appears to be an exciting new treatment modality for dry eye,” reported Dr Pflugfelder.
The nasal neurostimulation device includes a rechargeable base unit and disposable tip. It provides five levels of patient-adjustable stimulation to obtain tingling in the nose. After the tip is placed in the nostril, and the stimulus adjusted, patients begin to feel a gush of tears.
Dr Pflugfelder and colleagues conducted a multicentre randomised controlled clinical trial evaluating the effects of neurostimulation on lacrimal gland and goblet cell secretion. Patients with dry eye disease in the study had to have tear breakup time of less than seven seconds and a tear meniscus height of less than or equal to 240 microns. Patients and controls had a screening visit and two treatment visits. All patients underwent optical coherence tomography (OCT) and impression cytology, before and after neurostimulation.
The researchers took advantage of new OCT technology that allows measurement of the ocular surface at the micron level. They were able to measure the tear meniscus height to assess tear production using this technique. Measurement of inferior tear meniscus height showed significant increases following intranasal stimulation in both dry eye patients and normal controls.
Cytological studies compared intact and degranulated goblet cells. Patients treated with intranasal stimulation saw an associated increase in goblet cell degranulation and mucin production compared with those who received extranasal control treatment. The researchers also noted a treatment-associated increase in tear volume.
Stephen C Pflugfelder: firstname.lastname@example.org