Main Organiser

Julius Centre University of Malaya

Co-organiser

Department of Social and Preventive Medicine, Faculty of Medicine, University of Malay

Supported by

University of Malaya

LOW NOCTURNAL OCULAR PERFUSION PRESSURE AS A RISK FACTOR FOR NORMAL TENSION GLAUCOMA

Author

Norlina Ramli, Nurull,Bahiyah Suliman, Noran N Hairi, Mimiwati Zahari

Institution

University Malaya

Abstract

Objectives: To determine intraocular (IOP) and haemodynamic parameters relating to ocular perfusion pressures over a 24 hour period in patients with normal tension glaucoma (NTG) and normal patients (controls).

Methods: A cross sectional study of 72 NTG patients and 55 controls were recruited for IOP and blood pressure (BP) monitoring at two hourly intervals over a 24 hour period in a hospital ward setting. Optic nerve perfusion defined as ocular perfusion pressure is calculated as the difference between arterial BP and IOP. Measurements were divided into three time periods, daytime (0800- 1400 hours), evening (1600-2200 hours) and nocturnal (000-0600 hours).

Results: IOP were significantly higher and BP parameters lower for both groups in the nocturnal period (p<0.001). There were no significant differences between the NTG and normal patients in terms of IOP parameters. However NTG patients had significantly lower BP parameters compared with normal controls. This is reflected in significantly lower mean ocular perfusion pressure in NTG patients (p<0.005).

Conclusion: Office hour IOP reading does not reflect deficient ocular perfusion pressures seen in nocturnal period in NTG patients. Therapy should be targeted at haemodynamic parameters in this group.