Endothelin-1 plasma levels in normal-tension glaucoma: abnormal response to postural changes

Area of Science:

• Ophthalmology
• Vascular Biology
• Endocrinology

Background:

• Endothelin-1 (ET-1) is a potent vasoconstrictor implicated in vascular diseases.
• Elevated ET-1 plasma levels have been reported in normal-tension glaucoma (NTG) patients.

Purpose of the Study:

• To investigate ET-1 plasma levels and their association with vascular function in high-tension glaucoma (HTG), NTG, and control groups.
• To explore the role of vascular dysfunction in the pathogenesis of optic nerve damage in NTG.

Main Methods:

• Measured ET-1 concentration, plasma renin activity, and 24-h blood pressure in 21 HTG, 19 NTG, and 20 control subjects.
• Assessed ET-1 levels in supine and upright positions to evaluate physiological responses.

Main Results:

• ET-1 plasma levels showed a non-significant trend towards being higher in NTG patients.
• NTG patients exhibited significantly greater individual variability in ET-1 levels, indicating heterogeneity.
• The typical increase in ET-1 upon assuming an upright position was absent in NTG patients.
• Plasma renin activity tended to be lower in NTG patients, potentially explaining their lower blood pressure despite elevated ET-1.

Conclusions:

• Vascular dysfunction is a potential contributing factor to optic nerve damage in normal-tension glaucoma.
• The blunted ET-1 response to postural changes in NTG patients supports the hypothesis of impaired vascular regulation.