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M. Ono, M. Haida; Objective Discomfort: Non–Invasive Detection of Brain Activation of the Prefrontal Cortex From Eye Opening in Patients With Dry Eye by Near–Infrared Ray Spectroscopy (NIRS) Topography . Invest. Ophthalmol. Vis. Sci. 2006;47(13):256.
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© ARVO (1962-2015); The Authors (2016-present)
Discomfort is a primary symptom of diseases; however, without a direct complaint from the patient there is no other effective method that can communicate the discomfort to others. This study was designed to objectively detect ocular discomfort from the brain by near–infrared ray spectroscopy (NIRS) topography in patients with dry eye.
Six severe dry eye patients (DE) (3 males, 3 females; 51.8 +/– 15.9 years of age) and 6 normal controls (NC) matched for age and sex were enrolled. Utilizing an eye–opening task, ocular discomfort was numerically detected in the brain–activated area (24 channels) of the prefrontal cortex using the NIRS topography system ETG–100 (Hitachi Medical Co. Tokyo, Japan). Each set of measurements was performed sequentially in the dark for a total of 5 minutes. The task consisted of five 1–minute parts alternating between keeping the eyes closed, followed by opening the eyes with free blinking. For NC, four measurements were taken 1) ocular discomfort negative (ODN) in a naive condition, 2) ocular discomfort positive (ODP) by Schirmer 1 test, 3) post 0.1% sodium hyaluronic acid instillation (HAI) as a lubricant and 4) post 0.4% oxybuprocaine hydrochloride instillation (OBI) as an anesthetic. For DE, three measurements were taken 1) ODP in a naive condition, 2) HAI and 3) OBI. The subjective symptoms of ocular discomfort were scored, based on the Schirmer 1 test, as previously examined, as 10 points for all conditions.
Low brain activation was detected in NC–ODN and high brain activation was detected in both NC and DE–ODP. In ODP conditions, brain activation was partially suppressed by HAI (NC: p=0.03, DE: p=0.40) and suppressed by OBI (NC: p=0.03, DE: p=0.04). Subjective ocular discomfort correlated with objective brain activation (r=0.65, p=0.001).
Subjective discomfort can be objectified in patients with dry eye by brain activation of the prefrontal cortex while utilizing NIRS topography during an eye–opening task.
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