Blood flow per unit retinal nerve fibre tissue volume is lower in the human inferior retina

• Published in: British journal of ophthalmology Vol. 87; no. 2; pp. 184 - 188
• Main Authors: Harris, A, Ishii, Y, Chung, H S, Jonescu-Cuypers, C P, McCranor, L J, Kagemann, L, Garzozi, H J
• Format: Journal Article
• Language: English
• Published: BMA House, Tavistock Square, London, WC1H 9JR BMJ Publishing Group Ltd 01.02.2003; BMJ; BMJ Publishing Group LTD; Copyright 2003 British Journal of Ophthalmology
• Subjects: Adult; Biological and medical sciences; Capillaries - physiology; Cataracts; Clinical Science; Cross-Sectional Studies; Female; Glaucoma; Glaucoma and intraocular pressure; Humans; Laser-Doppler Flowmetry - methods; Lasers; Male; Medical sciences; Microcirculation - physiology; Nerve Fibers - physiology; Ophthalmology; Optic Disk - blood supply; optic nerve head; Regional Blood Flow - physiology; Retina; retinal blood flow; Retinal Vessels - physiology; scanning laser tomography; Tomography - methods; Human; Nervous system diseases; Optic nerve; Healthy subject; Pathophysiology; Inferior segment; Ocular hypertension; Retina; Neuropathy; Blood flow; Eye disease; Cranial nerve disease; Glaucoma (eye); Volume; Complication; Hemodynamics; Nervous tissue; Nerve fiber
• ISSN: 0007-1161; 1468-2079
• DOI: 10.1136/bjo.87.2.184

Aim: To determine if perfusion per unit tissue volume of retinal nerve fibre layer and optic nerve head in the inferior sector is lower than in the superior sector. Methods: Heidelberg retinal tomogram (HRT) for topographic measurement of optic nerve head and retinal nerve fibre layer and Heidelberg retinal flowmeter (HRF) for retinal blood flow were performed on 19 normal healthy subjects. Measurements from the superior and inferior sectors were compared. The perfusion/nerve fibre ratio (PNR); the blood flow per unit retinal nerve fibre tissue volume, was calculated in each sector with a formula; HRF flow measurements divided by HRT measurements. Results: Retinal nerve fibre layer thickness in the inferior retina was significantly higher than in the superior retina (p<0.05). There were, however, no differences in retinal blood flow between the superior and inferior retinal sectors. The PNR in the inferior sector were significantly lower than in the superior sector (p=0.047 for HRF mean flow/rim volume and p = 0.0282 for HRF 75th percentile flow/rim volume). Conclusions: The inferior sector of retinal nerve fibre layer and optic nerve head may have lower blood flow per unit nerve tissue volume compared to the superior sector. This result suggests that the inferior sector is more vulnerable to elevated intraocular pressure (IOP) and ischaemic insults in glaucomatous optic neuropathy.