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Optic nerve head change in non-arteritic anterior ischemic optic neuropathy and its influence on visual outcome.

ABSTRACT: To evaluate changes in cup/disc (C/D) diameter ratios and parapapillary atrophy in patients with non-arteritic anterior ischemic optic neuropathy (NA-AION), using morphometric methods.The clinical non-interventional study included 157 patients with unilateral or bilateral NA-AION. Optic disc photographs taken from both eyes at the end of follow-up were morphometrically examined.Follow-up was 86.3±70.3 months. Horizontal and vertical disc diameters (P = 0.30;P = 0.61, respectively), horizontal and vertical C/D ratios (P = 0.47;P = 0.19,resp.), and size of alpha zone and beta zone of parapapillary atrophy (P = 0.27;P = 0.32,resp.) did not differ significantly between affected eyes and contralateral normal eyes in patients with unilateral NA-AION. Similarly, horizontal and vertical disc diameters, horizontal and vertical C/D ratios, and size of alpha zone and beta zone did not vary significantly (all P>0.05) between the unaffected eyes of patients with unilateral NA-AION and the eyes of patients with bilateral NA-AION. Optic disc diameters, C/D ratios, size of alpha zone or beta zone of parapapillary atrophy were not significantly associated with final visual outcome in the eyes affected with NA-AION (all P>0.20) nor with the difference in final visual acuity between affected eyes and unaffected eyes in patients with unilateral NA-AION (all P>0.25).NA-AION did not affect C/D ratios nor alpha zone and beta zone of parapapillary atrophy. Optic disc size was not related to the final visual acuity outcome in NA-AION.

SUBMITTER: Jonas JB

PROVIDER: S-EPMC3357379 | biostudies-other | 2012

REPOSITORIES: biostudies-other

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Project description:Anterior ischemic optic neuropathy (AION) can be divided into nonarteritic (NAION) and arteritic (AAION) forms. NAION makes up ~85% of all cases of AION, and until recently was poorly understood. There is no treatment for NAION, and its initiating causes are poorly understood, in part because NAION is not lethal, making it difficult to obtain fresh, newly affected tissue for study. In-vivo electrophysiology and post-mortem studies reveal specific responses that are associated with NAION. New models of NAION have been developed which enable insights into the pathophysiological events surrounding this disease. These models include both rodent and primate species, and the power of a 'vertically integrated' multi-species approach can help in understanding the common cellular mechanisms and physiological responses to clinical NAION, and to identify potential approaches to treatment. The models utilize laser light to activate intravascular photoactive dye to induce capillary vascular thrombosis, while sparing the larger vessels. The observable optic nerve changes associated with rodent models of AION (rAION) and primate NAION (pNAION) are indistinguishable from that seen in clinical disease, including sectoral axonal involvement, and in-vivo electrophysiological data from these models are consistent with clinical data. Early post-infarct events reveal an unexpected inflammatory response, and changes in intraretinal gene expression for both stress response, while sparing outer retinal function, which occurs in AAION models. Histologically, the NAION models reveal an isolated loss of retinal ganglion cells by apoptosis. There are changes detectable by immunohistochemistry suggesting that other retinal cells mount a brisk response to retinal ganglion cell distress without themselves dying. The optic nerve ultimately shows axonal loss and scarring. Inflammation is a prominent early histological feature. This suggests that clinically, specific modulation of inflammation may be a useful approach to NAION treatment early in the course of the disease.

Project description:BackgroundMechanisms of peri-operative ischaemic optic neuropathy remain poorly understood. Both specific pre-operative and intra-operative factors have been examined by retrospective studies, but no animal model currently exists.ObjectivesTo develop a rodent model of peri-operative ischaemic optic neuropathy. In rats, we performed head-down tilt and/or haemodilution, theorising that the combination damages the optic nerve.DesignAnimal study.SettingLaboratory.AnimalsA total of 36 rats, in four groups, completed the functional examination of retina and optic nerve after the interventions.InterventionsAnaesthetised groups (n>8) were supine (SUP) for 5 h, head-down tilted 70° for 5 h, head-down tilted/haemodiluted for 5 h or SUP/haemodiluted for 5 h. We measured blood pressure, heart rate, intra-ocular pressure and maintained constant temperature.Main outcome measurementsRetinal function (electroretinography), scotopic threshold response (STR) (for retinal ganglion cells) and visual evoked potentials (VEP) (for transmission through the optic nerve). We imaged the optic nerve in vivo and evaluated retinal histology, apoptotic cells and glial activation in the optic nerve. Retinal and optic nerve function were followed to 14 and 28 days after experiments.ResultsAt 28 days in head down tilted/haemodiluted rats, negative STR decreased (about 50% amplitude reduction, P = 0.006), VEP wave N2-P3 decreased (70% amplitude reduction, P = 0.01) and P2 latency increased (35%, P = 0.003), optic discs were swollen and glial activation was present in the optic nerve. SUP/haemodiluted rats had decreases in negative STR and increased VEP latency, but no glial activation.ConclusionAn injury partly resembling human ischaemic optic neuropathy can be produced in rats by combining haemodilution and head-down tilt. Significant functional changes were also present with haemodilution alone. Future studies with this partial optic nerve injury may enable understanding of mechanisms of peri-operative ischaemic optic neuropathy and could help discover preventive or treatment strategies.

Project description:IntroductionThe peripapillary choroid shares a blood supply with and is directly apposed to the optic nerve, and therefore may contribute to the pathogenesis of non-arteritic anterior ischemic optic neuropathy (NAION). Prior studies evaluating peripapillary choroidal thickness (PCT) or choroidal vascularity index (CVI; the ratio of the perfused area to total choroid area) have produced mixed results. None investigated the relationship between PCT and CVI or demonstrated functional correlates. We hypothesized that greater PCT and lower CVI would correlate with visual function in patients presenting with NAION.MethodsSeventeen eyes with NAION (9 acute, 8 non-acute) and 6 unaffected "fellow" eyes in 13 patients, and 18 eyes in 18 age-matched control subjects were imaged using swept-source optical coherence tomography (SS-OCT) prospectively between 2017-2018. Mean PCT and CVI measurements were compared across groups and with respect to corresponding automated perimetric performance at the same visit.ResultsAnalysis of variance showed significantly greater PCT (NAION: 278 ± 65 μm, Fellow: 221 ± 50 μm, Control: 158 ± 27 μm, p<0.001) and lower CVI (NAION: 0.35 ± 0.03, Fellow: 0.35 ± 0.04, Control: 0.38 ± 0.02, p<0.005) in patients with NAION compared to control subjects. Bonferroni-corrected pairwise comparisons showed greater PCT and lower CVI in NAION-affected eyes compared to control eyes (p values<0.008), and no significant differences in PCT or CVI between NAION and fellow eyes (p values>0.06). PCT was negatively correlated with CVI among unaffected fellow eyes (r=-0.8, p<0.05), but not among acute NAION eyes (r=-0.1, p>0.7), non-acute NAION eyes (r=0.1, p>0.7), or controls (r=-0.3, p>0.2). Nasal CVI was positively correlated with mean deviation scores in non-acute NAION (r=0.8, p<0.02), but not among fellow unaffected eyes (r=0.8, p>0.05) or acutely affected NAION eyes (r=-0.3, p>0.4). Mean and temporal PCT correlated with pattern standard deviation scores among unaffected fellow eyes (r=0.8, p<0.04; r=0.9, p<0.03), but not among acute NAION eyes (r=-0.2, p>0.5; r=-0.1, p>0.7) or non-acute NAION eyes (r=0.1, p>0.7; r=0.05, p>0.9).ConclusionNAION and unaffected fellow eyes demonstrate increased choroidal thicknesses and reduced vascular density. Perimetric performance is directly associated with vascular density among non-acutely affected eyes with NAION. Ongoing work will provide further insights into these structure-function relationships with pathogenic and pathophysiologic relevance.

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Optic nerve head change in non-arteritic anterior ischemic optic neuropathy and its influence on visual outcome.

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