Non-arteritic anterior ischaemic optic neuropathy in Malaysia: A 5 years review

Department of Ophthalmology, School of Medical Sciences, Universiti Sains Malaysia, Health Campus, 16150 Kubang Kerian, Kelantan, Malaysia.
International journal of ophthalmology 06/2011; 4(3):272-4. DOI: 10.3980/j.issn.2222-3959.2011.03.12
Source: PubMed


To evaluate the clinical presentations and visual outcomes of non-arteritic anterior ischaemic optic neuropathy (NAION).
A retrospective study was conducted involving 18 consecutive patients (20 eyes) with NAION attending Hospital Universiti Sains Malaysia from January 2005 until December 2009.
Most patients were Malay (94.4%), and followed by Chinese (5.6 %). The female-to-male ratio was 3.5:1. The age of patients ranged from 36 to 85 years (mean, 57.1 years). The main risk factors in systemic diseases were hypertension (55.5%), diabetes mellitus (44.4%), and ischaemic heart disease (11.1%). Most patients (77.8%) presented with acute loss of vision while gradual onset was in 22.3% of cases. Majority had visual acuity worse than 1/60 (80%). The most common fundoscopic findings were peripapillary splinter haemorrhage (90%), sectorial swollen optic disc (60%) and hyperemic disc (60%). During follow up, 20% of the patients showed stabilization in visual acuity, and 80% showed worsening of vision.
Majority of patients with NAION presented with acute poor vision involving middle-aged and elderly individuals. Hypertension and diabetes mellitus were among the main risk factors involved. NAION can lead to permanent visual loss despite treatment.

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    ABSTRACT: The scientific community continues to accrue evidence that blood flow alterations and ischemic conditions in the retina play an important role in the pathogenesis of ocular diseases. Many factors influence retinal hemodynamics and tissue oxygenation, including blood pressure, blood rheology, oxygen arterial permeability and tissue metabolic demand. Since the influence of these factors on the retinal circulation is difficult to isolate in vivo, we propose here a novel mathematical and computational model describing the coupling between blood flow mechanics and oxygen ([Formula: see text]) transport in the retina. Albeit in a simplified manner, the model accounts for the three-dimensional anatomical structure of the retina, consisting in a layered tissue nourished by an arteriolar/venular network laying on the surface proximal to the vitreous. Capillary plexi, originating from terminal arterioles and converging into smaller venules, are embedded in two distinct tissue layers. Arteriolar and venular networks are represented by fractal trees, whereas capillary plexi are represented using a simplified lumped description. In the model, [Formula: see text] is transported along the vasculature and delivered to the tissue at a rate that depends on the metabolic demand of the various tissue layers. First, the model is validated against available experimental results to identify baseline conditions. Then, a sensitivity analysis is performed to quantify the influence of blood pressure, blood rheology, oxygen arterial permeability and tissue oxygen demand on the [Formula: see text] distribution within the blood vessels and in the tissue. This analysis shows that: (1) systemic arterial blood pressure has a strong influence on the [Formula: see text] profiles in both blood and tissue; (2) plasma viscosity and metabolic consumption rates have a strong influence on the [Formula: see text] tension at the level of the retinal ganglion cells; and (3) arterial [Formula: see text] permeability has a strong influence on the [Formula: see text] saturation in the retinal arterioles.
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