title: The effect of posture on the intraocular pressure and pulsatile ocular blood flow in patients with non-arteritic anterior ischaemic optic neuropathy.
abstract: Intraocular pressure (IOP) and pulsatile ocular bloodflow (POBF) have been recorded in 15 patients with unilateral non-arteritic anterior ischaemic optic neuropathy (na-AION) and in 28 healthy subjects of comparable age. Measurements were obtained in both the upright and lying postures with a pneumotonometer linked to a Langham ocular bloodflow system. By comparison with the healthy subjects, patients with na-AION were found to have a significantly greater postural pressure change in IOP (3.9 +/- 0.4 mmHg in the affected eye and 3.6 +/- 0.6 mmHg in the unaffected eye of the patients with na-AION compared to 2.2 +/- 0.4 mmHg in the right eye of the healthy subjects P less than 0.01 and less than 0.05 respectively). There was no significant difference between the IOP in the affected and unaffected eyes of patients with na-AION nor between this group and the healthy subjects in either posture. Pulsatile ocular bloodflow measurements were similar in both groups and in both eyes of the patients with na-AION. In both groups POBF fell significantly on lying down (healthy right eyes -84 +/- 16 ul/min p less than 0.01, na-AION affected eye -84 +/- 24 ul/min p less than 0.01, unaffected eye -83 +/- 26 ul/min p less than 0.001). These figures represent decrements of 19% in all groups. These findings suggest that assumption of the supine posture may be associated with a reduction in the pulsatile component of ocular perfusion. The importance of this in the pathogenesis of na-AION is discussed.
authors.affiliation: Division of Pharmacological Sciences and Toxicology, United Medical School, Guy's Hospital, London.
authors.forename: C B
authors.initials: CB
authors.lastname: James
authors.forename: S E
authors.initials: SE
authors.lastname: Smith
mesh_terms: D000328:Adult; D000368:Aged; D001794:Blood Pressure; D005260:Female; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology*; D007511:Ischemia / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D009898:Optic Disk / Q000098:blood supply*; D009901:Optic Nerve Diseases / Q000503:physiopathology*; D011187:Posture / Q000502:physiology*; D011673:Pulsatile Flow / Q000502:physiology*; D012039:Regional Blood Flow; D013484:Supination / Q000502:physiology