Analysis of prothrombotic and vascular risk factors in patients with nonarteritic anterior ischemic optic neuropathy

Evaluation and management of nonarteritic anterior ischemic optic neuropathy: a national survey

PURPOSE

The evaluation and management of Nonarteritic Anterior Ischemic Optic Neuropathy (NAION) lacks standardized guidelines. This study aimed to investigate the real-world practices of neuro-ophthalmologists in the evaluation and management of typical NAION cases.

METHODS

A national survey, conducted between 2019 and 2021, involved all practicing neuro-ophthalmologists. A structured questionnaire assessed their approach to risk factor evaluation and treatment of NAION, with 19 questions about risk factors and six questions concerning treatment and prevention of fellow-eye involvement.

RESULTS

Thirty-six out of 37 neuro-ophthalmologists participated. Most physicians referred patients for evaluation of the following risk factors: obstructive sleep apnea (83.3%), diabetes mellitus (83.3%), hypertension (77.7%), dyslipidemia (72.2%), and optic disc drusen (38.8%). However, there was considerable variation in the choice of diagnostic tests recommended. Furthermore, nearly 47% recommended an embolism workup. Regarding treatment, the majority (91%) did not recommend routine treatment for NAION, although in 16.7%, high-dose corticosteroids were occasionally prescribed. Secondary prevention with aspirin (80.6%), smoking cessation advice (86.1%), and advising against erectile dysfunction medications for men (80.6%) were common recommendations.

CONCLUSION

While the risk factors associated with NAION are well-reported, there is a lack of uniformity on which tests should be ordered to evaluate these risk factors. Most neuro-ophthalmologists concur that routine treatment for NAION is not warranted, but not unanimously. Future studies to develop a consensus guideline for post-NAION work-up and management recommendations may assist in the detection and management of preventable risk factors.

Study of nycthemeral variations in blood pressure in patients with non-arteritic anterior ischemic optic neuropathy

PURPOSE

The objective of this study was to analyze the nycthemeral variations in blood pressure (BP) in individuals who presented with non-arteritic anterior ischemic optic neuropathy (NAION).

METHODS

BP was recorded for 24 h (ambulatory blood pressure monitoring, ABPM) in 65 patients with acute NAION. Three definitions of nighttime periods were used: definition 1, 1 a.m.-6 a.m.; definition 2, 10 p.m.-7 a.m.; and definition 3, 10 p.m.-8 a.m. For each of these definitions, patients were classified according to the value of nocturnal reduction in BP into dippers (10-20%), mild dippers (0-10%), reverse dippers (< 0%), and extreme dippers (> 20%).

RESULTS

The proportions of dippers, mild dippers, reverse dippers, and extreme dippers varied significantly depending on the definition chosen. We found the highest number of patients with extreme dipping (23%) when using the strictest definition of nighttime period (definition 1, 1 a.m.-6 a.m.), as compared with 6.2% and 1.5% for the other definitions, respectively. Overall, 13 of 33 patients without known systemic hypertension (39%) were diagnosed with hypertension after ABPM. No risk factor for NAION was associated with the extreme-dipping profile. Finally, the prevalence of systemic hypertension was high (69%).

CONCLUSION

In our population of patients who had an episode of NAION, the proportion of extreme dippers was higher than that usually found in the literature. However, extreme dipping is not a frequent feature of patients with NAION as compared to patients with systemic hypertension. ABPM is recommended for all patients with NAION and unknown history of systemic hypertension.

Ophthalmic and Systemic Factors of Acute Nonarteritic Anterior Ischemic Optic Neuropathy in the Quark207 Treatment Trial

PURPOSE

We describe the baseline ophthalmic and cardiovascular risk factors across countries, race, and sex for the Quark207 treatment trial for acute nonarteritic anterior ischemic optic neuropathy (NAION).

DESIGN

Prospective, randomized controlled clinical trial.

PARTICIPANTS

Adults 50 to 80 years of age with acute NAION recruited from 80 sites across 8 countries.

MAIN OUTCOME MEASURES

Ophthalmic features of NAION and cardiovascular risk factors.

METHODS

We evaluated demographics and clinical and ophthalmologic data, including best-corrected visual acuity (BCVA) and average visual field total deviation (TD), in affected eyes and cup-to-disc ratio in fellow eyes at enrollment. We report the prevalence (mean and standard devition, and median and interquartile range [IQR]) of ophthalmic features and cardiovascular risk factors, stratified by country, race, and sex. We corrected for multiple comparisons using Dunn's test with Bonferroni correction for continuous variables and chi-square testing with Holm-Bonferroni correction for categorical variables.

RESULTS

The study enrolled 500 men and 229 women with a median age of 60 and 61 years (P = 0.027), respectively. Participants were predominantly White (n = 570) and Asian (n = 149). The study eye BCVA was 71 characters (IQR, 53-84 characters; approximately 0.4 logarithm of the minimum angle of resolution), and the TD was -16.5 dB (IQR, -22.2 to -12.6 dB) for stimulus III and -15.7 dB (IQR, -20.8 to -10.9 dB) for stimulus V. The vertical and horizontal cup-to-disc ratio was 0.1 (IQR, 0.1-0.3) for unaffected fellow eyes. The prevalence of cardiovascular risk factors varied among countries. The most notable differences were in the baseline comorbidities and ophthalmologic features, which differed between Asian and White races. Men and women differed with respect to a few clinically meaningful features.

CONCLUSIONS

The cardiovascular risk factors in the NAION cohort varied among the 7 countries, race, and sex, but were not typically more prevalent than in the general population. Ophthalmic features, typical of NAION, generally were consistent across countries, race, and sex, except for worse BCVA and TD in China. Men have a frequency of NAION twice that of women. Having a small cup-to-disc ratio in the fellow eye was the most prevalent risk factor across all demographics. This study suggests that factors, not yet identified, may contribute to the development of NAION.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Bilateral Simultaneous Nonarteritic Anterior Ischemic Optic Neuropathy: Demographics, Risk Factors, and Visual Outcomes

BACKGROUND

Although nonarteritic anterior ischemic optic neuropathy is a well-known cause of vision loss, it typically presents unilaterally. Simultaneous, bilateral nonarteritic anterior ischemic optic neuropathy (sNAION) is rare and poorly studied in comparison. This study seeks to characterize the clinical features and risk factors of patients with sNAION compared with unilateral NAION (uNAION).

METHODS

In this retrospective case-control study, we reviewed 76 eyes (38 patients) with sNAION and 38 eyes (38 patients) with uNAION (controls) from 4 academic institutions examined between 2009 and 2020. Demographic information, medical history, medication use, symptom course, paraclinical evaluation, and visual outcomes were collected for all patients.

RESULTS

No significant differences were observed in demographics, comorbidities and their treatments, and medication usage between sNAION and uNAION patients. sNAION patients were more likely to undergo an investigative work-up with erythrocyte sedimentation rate measurement ( P = 0.0061), temporal artery biopsy ( P = 0.013), lumbar puncture ( P = 0.013), and MRI ( P < 0.0001). There were no significant differences between the 2 groups for visual acuity, mean visual field deviation, peripapillary retinal nerve fiber layer thickness, or ganglion cell-inner plexiform layer thickness at presentation, nor at final visit for those with ≥3 months of follow-up. The sNAION eyes with ≥3 months of follow-up had a smaller cup-to-disc ratio (CDR) at final visit ( P = 0.033). Ten patients presented with incipient NAION, of which 9 suffered vision loss by final visit.

CONCLUSION

Aside from CDR differences, the risk factor profile and visual outcomes of sNAION patients seem similar to those of uNAION patients, suggesting similar pathophysiology.

[Optical coherence tomography analysis of the optic nerve head and macula of the fellow eye in acute unilateral nonarteritic anterior ischemic optic neuropathy]

INTRODUCTION

The objective of the study was to compare the thickness of the retinal nerve fiber layer (RNFL) and ganglion cell complex (GCC) of the fellow eyes of patients with acute nonarteritic anterior ischemic optic neuropathy (NAAION) to those of control subjects.

METHODS

This study included 46 patients with NAAION matched for age, sex and refraction data (spherical equivalent and/or axial length) to 46 control subjects. The anatomical parameters assessed using the Cirrus SD-OCT were the mean RNFL thickness, in the 4 quadrants (inferior, nasal, temporal, superior) and according to the 12 hourly meridians, GCC mean and in 6 quadrants centered on the fovea (infero-nasal, supero-nasal, infero-temporal, supero-temporal, superior and inferior) and parameters of the optic disc (Cup ratio - Vertical and Average Disc, Rim Area, Disc Area, Cup Volume).

RESULTS

Compared to the control group, the eyes contralateral to those affected by NAAION showed a greater value of the area of the neuro-retinal rim (rim area), and a smaller vertical cup/disc (C/D) ratio, mean C/D, and cup volume than the control group. There was no significant difference between the two groups for peripapillary RNFL thickness and GCC parameters.

CONCLUSION

The absence of damage to the RNFL or GCC of the unaffected fellow eyes of patients with NAAION does not explain the perimetric damage. The eyes contralateral to those affected by NAAION are characterized by an overall size of the optic disc identical to those of the control subjects, but a smaller cup, a recognized risk factor for NAAION.

Characteristics of macrophage-like cells in acute nonarteritic anterior ischemic optic neuropathy and the normal fellow eyes on en face optical coherence tomography

Purpose

To quantitatively analyze macrophage-like cells (MLCs) at the vitreoretinal interface (VRI) in acute nonarteritic anterior ischemic optic neuropathy (NAION) using en face swept-source optical coherence tomography (OCT).

Methods

Twenty-five acute NAION eyes and 25 normal fellow eyes from 25 patients were included in the study. MLCs were visualized in a 3 μm 6 mm×6 mm en face OCT slab above the VRI centered on the optic nerve head (ONH). After semiautomatic binarization and quantification, we evaluated the MLC density between the two groups. We also investigated the relationship between MLC density and other OCT parameters, including the increase in peripapillary retinal nerve fiber layer (RNFL) thickness and loss of vessel density (VD) in radical peripapillary capillary (RPC).

Results

The MLC density in the affected eye of the ONH was highly correlated with that in the fellow eye (r=0.612, p=0.001). The MLC density significantly increased in acute NAION eyes (NAION vs. normal, 11.97 ± 6.66 vs. 9.31 ± 6.10 cell/mm², p=0.028). In sectorial analysis, the increase in MLCs was mainly in the superior regions (4.13 ± 7.49 vs. 0.94 ± 5.21 cell/mm², p=0.001). The VD of RPC decreased significantly in the affected eyes (NAION vs. normal, 37.54 ± 5.25 vs. 40.56 ± 4.25, p=0.016), and the loss of RPC was predominantly in the superior sectors and the temporal sectors when compared to the inferior sectors and the nasal sectors, respectively (superior vs. inferior, -3.54 ± 6.71 vs. -0.37 ± 8.07, p=0.004; temporal vs. nasal, -2.69 ± 8.72 vs. -1.22 ± 6.06, p=0.005). The loss of RPC and the increase in MLC density were greater in affected sector corresponding to the visual field (VF) defect.

Conclision

MLCs located above the VRI increased significantly in acute NAION eyes, especially in subregions corresponding to VF defect, which provides clinical evidence supporting that the inflammatory response participates in the pathological process of NAION. The magnitude of the increase in MLCs corresponds to the RPC loss in the quadrant analysis.

Risk Factors for Fellow Eye Involvement in Patients with Nonarteritic Anterior Ischemic Optic Neuropathy

INTRODUCTION

The aim of the study was to investigate the possible risk factors for fellow eye involvement in patients with nonarteritic anterior ischemic optic neuropathy (NAION).

METHODS

A total of 113 patients with unilateral NAION attack were included and divided into two groups according to whether fellow eye involvement was present over a mean follow-up period of 2.70 years (P25-P75: 0.77-3.54 years). General characteristics (including age, sex, diabetes, hypertension, hyperlipidemia, and obstructive sleep apnea syndrome [OSAS]) and ocular characteristics (including initial best-corrected visual acuity, initial visual field damage of the first eye, and the presence/absence of a crowded disc) were analyzed and compared between the two groups. Cox regression was used to assess the risk factors for fellow eye involvement.

RESULTS

During the follow-up period, 40 patients developed fellow eye involvement. The initial best-corrected visual acuity (p = 0.048) and mean deviation of the visual field (VF) (p = 0.039) of the first eye in patients with fellow eye involvement were worse than those in patients without it. Diabetes (HR = 3.06, 95% CI: 1.50, 6.26, p = 0.002) and increased VF damage (moderate vs. mild, HR = 2.92, 95% CI: 1.03, 8.25, p = 0.043; severe vs. mild, HR = 5.01, 95% CI: 1.65, 15.20, p = 0.004) were associated with a significantly increased risk of fellow eye involvement. In 57 patients with apnea-hypopnea index (AHI) data for further study, an AHI score ≥23.2 was also found to be a risk factor (HR = 3.36, 95% CI: 1.17, 9.69, p = 0.025).

CONCLUSION

Diabetes, severer initial VF damage, and more severe OSAS were risk factors for fellow eye involvement in NAION. For patients with these risk factors, more intensive follow-ups might be warranted.

Neuroprotection and Neuroregeneration Strategies Using the rNAION Model: Theory, Histology, Problems, Results and Analytical Approaches

Nonarteritic anterior ischemic optic neuropathy (NAION) is the most common cause of sudden optic nerve (ON)-related vision loss in humans. Study of this disease has been limited by the lack of available tissue and difficulties in evaluating both treatments and the window of effectiveness after symptom onset. The rodent nonarteritic anterior ischemic optic neuropathy model (rNAION) closely resembles clinical NAION in its pathophysiological changes and physiological responses. The rNAION model enables analysis of the specific responses to sudden ischemic axonopathy and effectiveness of potential treatments. However, there are anatomic and genetic differences between human and rodent ON, and the inducing factors for the disease and the model are different. These variables can result in marked differences in lesion development between the two species, as well as in the possible responses to various treatments. These caveats are discussed in the current article, as well as some of the species-associated differences that may be related to ischemic lesion severity and responses.

Treatment of nonarteritic anterior ischemic optic neuropathy with an endothelin antagonist: ENDOTHELION (ENDOTHELin antagonist receptor in Ischemic Optic Neuropathy)—a multicentre randomised controlled trial protocol

Background

Nonarteritic anterior ischemic optic neuropathy (NAAION) is a major cause of blindness in individuals over 50 years of age, with no available effective treatment. The oral dual endothelin receptor antagonist, bosentan, increases retinal optic nerve head blood flow in healthy humans and glaucoma patients. The objective of this trial is to assess the efficacy of bosentan administered at the acute stage in improving outcomes in NAAION patients.

Methods

ENDOTHELION (ENDOTHELin antagonist receptor in Ischemic Optic Neuropathy) is a phase III, interventional, prospective, multicentre, placebo-controlled randomised double-blind clinical trial. The primary outcome is change in the visual field mean deviation (MD) at 3 months (Humphrey 30-2 SITA standard programme). Secondary outcomes include MD and visual acuity changes up to 24 months, changes in peripapillary retinal nerve fibre and macular ganglion cell layer thickness in the affected eye, as measured by optical coherence tomography, rate of NAAION bilateralisation at 2 years, and quality-of-life. Patients over 50 years of age presenting with typical NAAION of recent onset (less than 21 days) are randomly assigned to either 125 mg oral bosentan or placebo, twice a day, during 8 weeks. Besides visits during the treatment phase, patients attend follow-up visits at 2, 3, 6, 12 and 24 months. The inclusion of patients began in August 2015 at five French University hospital ophthalmology departments and two specialised ophthalmology centres. It is planned to include 86 patients in this trial. To date we have included 72 patients and 49 have completed the full follow-up process.

Discussion

An endothelin receptor antagonist is a potential approach to improving the anatomical and functional prognosis of patients with NAAION. This multicentre double-blind randomised controlled trial is an opportunity to assess (1) the effect of bosentan on the structure and function of the optic nerve in NAAION, at 3 months, (2) the effect of bosentan on the bilateralisation rate at 24 months and (3) the tolerance profile of bosentan in this population.

Trial registration

ClinicalTrials.gov NCT02377271. Registered on March 3, 2015.

Analysis of Systemic Risk Factors and Post-Insult Visual Development in a Danish Cohort of Patients with Nonarteritic Anterior Ischemic Optic Neuropathy

Purpose

Nonarteritic anterior ischemic optic neuropathy (NAION) is associated with vascular as well as anatomical risk factors. Following the insult, the visual development varies from minor to severe deterioration. The aim of this study was to examine possible prognostic systemic risk factors and their eventual impact on post-insult visual development in NAION patients.

Methods

A retrospective chart review of all NAION patients (18-79 years at time of diagnosis) seen a minimum of two times in a tertiary eye department during a 10-year period in regard to systemic diseases, medication, lifestyle factors and ophthalmic examination was performed. Visual outcome was assessed according to the development of best corrected visual acuity (BCVA) and visual field from initial to final visit.

Results

There were 163 eligible patients. A greater proportion of the patients in the total cohort were over 50 years of age (79.8%) and men (66.3%). In total, 59.5% of the patients had a stable BCVA, while 25.8% experienced improvement, and 14.7% had deterioration. Seventy-two percent of the patients had a stable visual field, while 14% had improvement, and 14% had deterioration. No association between visual outcome and clinical characteristics, medication or systemic risk factors were identified.

Conclusion

We did not find any association between patient characteristics and systemic risk factors at time of diagnosis and visual development post-insult. This could suggest that the optic nerve head anatomy plays a larger role for visual outcome than previously estimated.

Metabolic syndrome and its components are associated with non-arteritic anterior ischaemic optic neuropathy

PURPOSE

To determine whether metabolic syndrome (MetS) is a risk factor for various forms of optic neuropathy including non-arteritic anterior ischaemic optic neuropathy (NAION).

METHODS

This population-based analysis identified patients ≥40 years of age in Olmsted County, Minnesota, USA using the Rochester Epidemiology Project 2005-2018. Patients with MetS were identified if three or more of the five standard criteria for diagnosing MetS were present: systemic hypertension, hyperglycaemia, hypertriglyceridaemia, reduced high-density lipoprotein cholesterol (hypoalphalipoproteinaemia) and central adiposity defined by increased body mass index. Charts of patients identified as having an optic neuropathy were reviewed to record specific diagnoses and compared with patients without ocular pathology other than cataract. The odds ratio (OR) of association with MetS was calculated and adjusted for age, sex and race with multivariate analysis for the various optic neuropathies.

RESULTS

Patients with MetS were more likely to have an optic neuropathy than those without (OR 2.2, p<0.001). After adjusting for age, sex and race, the only optic neuropathy found to be significantly associated with MetS was NAION (OR 6.17, p=0.002). For patients with NAION, though each individual component of MetS was individually significantly associated with MetS, further analysis suggested that hypertriglyceridaemia, hypoalphalipoproteinaemia and hyperglycaemia were likely the key drivers in the overall significance between NAION and MetS.

CONCLUSION

Patients with MetS were more likely to have NAION. Further studies are needed to determine whether MetS is a modifiable risk factor for NAION.

Risk Factors for Non-arteritic Anterior Ischemic Optic Neuropathy: A Large Scale Meta-Analysis

Objective: We conducted a meta-analysis to explore all the potential risk factors for non-arteritic anterior ischemic optic neuropathy (NAION) based on the published literature. Methods: A comprehensive literature search through the online databases was performed to obtain studies concerning the risk factors of NAION up to June 2020. Pooled unadjusted odds ratios (ORs) or rate ratios (RRs) were calculated to evaluate the weight of risk factors. This study was registered in PROSPERO under the number CRD42018084960. Results: Our meta-analysis included 49 original studies comprising of more than 10 million patients. The following risk factors were proved to be significantly associated with NAION: male gender (OR = 1.67, 95% CI: 1.50-1.85, P < 0.00001), hypertension (RR = 1.28, 95% CI: 1.20-1.37, P < 0.00001), hyperlipidemia (RR = 1.43, 95% CI: 1.26-1.62, P < 0.00001), diabetes mellitus (DM) (RR = 1.53, 95% CI: 1.36-1.73, P < 0.00001), coronary heart disease (CHD) (RR = 1.68, 95% CI: 1.24-2.27, P = 0.0008), sleep apnea (RR = 3.28, 95% CI: 2.08-5.17, P < 0.00001), factor V Leiden heterozygous (RR = 2.21, 95% CI: 1.19-4.09, P = 0.01), and medication history of cardiovascular drugs. Conclusion: We concluded that the above risk factors were significantly related to NAION. Better understanding of these risk factors in NAION can help the direct therapeutic approaches.

Non-Arteritic Anterior Ischemic Optic Neuropathy (NAION) Following a Hypovolemic Episode of Gastric Bleeding

Non-arteritic anterior ischemic optic neuropathy (NAION) is a rare complication following acute bleeding. Patients present with varying vision loss and visual field defects. NAION is more commonly developed in patients with systemic disorders that may affect normal blood flow such as hypertension and diabetes. In this case, we report a 54-year-old man who complained of vision blurring following an episode of acute gastric bleeding. This report aims to review the pathology of this condition and present the findings of newer non-invasive imaging modalities of the vascular layers of the posterior pole of the eye like optical coherence tomography angiography (OCTA), which facilitates the proper diagnosis and prognosis of such cases. Finally, we present the management options for this patient with antiplatelet treatment.

Association Study of MTHFR Polymorphisms with Nonarteritic Anterior Ischemic Optic Neuropathy in a Spanish Population

Introduction

Nonarteritic anterior ischemic optic neuropathy (NAION), painless loss of central and/or peripheral vision, is a multifactorial disease caused by insufficient blood flow through the posterior ciliary arteries to the optic nerve head. Mutations in the methylenetetrahydrofolate reductase (MTHFR) gene, triggering hyperhomocysteinemia as a consequence of a decreased activity of the codified enzyme, have been considered to be among the risk factors of NAION.

Objective

The main aim was to study the association of the most common MTHFR genetic polymorphisms C677T and A1298C with NAION in a Spanish population.

Methods

In this case-control study, the association of the most common MTHFR polymorphisms was investigated in 94 unrelated native Spanish patients diagnosed with NAION and 204 healthy controls. Two single nucleotide polymorphisms located in the MTHFR gene, C677T (rs1801133) and A1298C (rs1801131), were analyzed by DNA sequencing and TaqMan assays.

Results

The allelic and genotypic frequencies of the MTHFR variants obtained in the NAION group were not significantly different when compared with the control group. A higher frequency of the C677T/A1298C genotype, codifying the nonmutated MTHFR form, was obtained in control subjects (11.27%) compared to NAION patients (4.26%), suggesting a protective effect of the wild-type protein, although this result was not conclusive considering the obtained confidence interval (CI) (95% CI: 0.13-1.06). Study of additional clinical factors including hypertension, diabetes mellitus, and dyslipidemia showed no association with a higher risk of NAION. Conversely, the clinical history of heart or cerebrovascular diseases was significantly higher in NAION patients compared to controls. Over the world, risk variants of the MTHFR gene are highly frequent, excluding African black populations, indicating a racial influence.

Conclusions

The MTHFR variants did not significantly increase the risk of suffering from NAION. However, considering that individuals with at least one of the risk variants have the MTHFR enzyme with decreased activity, it cannot be ruled out that these mutations are relevant for the development of NAION in a subgroup of the population with other specific characteristics. These may include high plasma levels of homocysteine along with nutritional deficiencies including low folate or vitamin B12 and the combination of systemic and local risk factors.

Risk Factors for Fellow Eye Involvement in Nonarteritic Anterior Ischemic Optic Neuropathy

BACKGROUND

Nonarteritic anterior ischemic optic neuropathy (NAION) is the most common acute optic neuropathy in individuals older than 50 years. Demographic, ocular, and systemic risk factors for NAION have been identified, and we sought to determine which, if any, of these factors also increase risk of NAION in the fellow eye.

METHODS

We performed a retrospective chart review of patients with "ischemic optic neuropathy" (based on International Classification of Disease [ICD] codes) seen at a single eye center between 2007 and 2017. Patients who met diagnostic criteria for unilateral NAION without fellow eye optic neuropathy at diagnosis were included. Demographic information, ocular comorbidities, and systemic diagnoses were recorded, in addition to whether the fellow eye developed NAION during the follow-up period. Univariate and multivariate Cox proportional hazard regression were used to calculate hazard ratios (HRs) for fellow eye involvement.

RESULTS

Three hundred eighteen patients were identified by ICD codes, and 119 were included in the study. Twenty-nine (24%) patients developed NAION in the fellow eye over the mean follow-up period of 3.6 years (range: 1 month-11 years). Significant risk factors for fellow eye NAION included the presence of bilateral optic disc drusen (ODD, HR 2.78, 95% confidence interval [CI] 1.12-6.90, P = 0.02) and noncompliance with continuous positive airway pressure (CPAP) in patients with moderate-to-severe obstructive sleep apnea (HR 4.50, 95% CI 1.79-11.3, P = 0.0015).

CONCLUSIONS

Bilateral ODD and noncompliance with CPAP when indicated are associated with increased risk of NAION in the fellow eye. Patients with these risk factors should be counseled on the potentially devastating visual consequences of bilateral NAION, and compliance with CPAP should be stressed when appropriate.

Natural history and visual outcome of nonarteritic anterior ischemic optic neuropathy in Southern Taiwan: a pilot study

PURPOSE

To investigate the natural course, visual outcome, and risk factors for visual loss after nonarteritic anterior ischemic optic neuropathy (NAION) attack in Chinese patients from a tertiary medical center in Southern Taiwan.

METHODS

This is a longitudinal observational study that included sixty NAION patients, who were seen in our neuro-ophthalmology clinic from 2007 to 2016. Records of their ophthalmic history, medical history, best-corrected visual acuity (BCVA), visual field (VF) testing, and optical coherence tomography (OCT) were obtained for analysis.

RESULTS

When the first visit was within two weeks after NAION onset, 62% of patients had BCVA of less than 0.1 (logMAR BCVA ≥ 1) and 38% had at least moderate-severe depression (VF grade ≥ 3) on VF on the initial visit. VA stabilized at three months after onset and was predictive of VA at 12 months. Diabetes mellitus was a risk factor associated with VA worsening. Sixty-one percent of patients had BCVA of less than 0.1 at 12 months after onset. VF remained relatively unchanged during the disease, with 41% eyes having VF grade ≥ 3 at 12 months after onset. On OCT, all quadrants of retinal nerve fiber layer thickened initially, returned to the level of the fellow eye at one month, and continued thinning up to 12 months slowly.

CONCLUSION

In Southern Taiwan, a higher proportion of Chinese patients (over half) presented with severe visual loss during the first two weeks of NAION attack and at 12 months after the onset of NAION as compared to the findings previously reported in Caucasians. Understanding the natural course of NAION in Chinese patients may provide insights toward a possible therapeutic window for NAION treatments in this group of patients.

Risk of Stroke After Nonarteritic Anterior Ischemic Optic Neuropathy

PURPOSE

To determine whether nonarteritic ischemic optic neuropathy (NAION) raises the risk of subsequent stroke in the general population.

DESIGN

Population-based, retrospective cohort study.

METHODS

Setting: Nationwide, population-based, retrospective cohort study.

PATIENTS

Of 1 025 340 beneficiaries in the National Health Insurance Service-National Sample Cohort database (2002-2013), we included 400 952 eligible individuals in the analysis.

OBSERVATIONS

To determine the effect of incident NAION on the occurrence of subsequent stroke, we used time-varying covariate Cox regression models. Model 1 included only incident NAION as a time-varying covariate. Model 2 included Model 1 and defined demographics. Model 3 included Model 2, comorbidity, co-medication, and Charlson index score.

MAIN OUTCOME MEASURES

Effect (hazard ratio [HR]) of NAION on stroke development.

RESULTS

Of 400 952 eligible individuals, 1125 patients developed NAION and 16 998 patients suffered from stroke. NAION was not associated with an increased risk of subsequent stroke in Model 1, with HR of 1.31 (95% confidence interval [CI], 0.89-1.92). This was consistent, after adjusting for demographics and/or confounding factors, in Model 2 (HR = 1.19, 95% CI, 0.81-1.75) and Model 3 (HR = 1.10, 95% CI, 0.75-1.62).

CONCLUSIONS

Our results suggest that NAION per se is not associated with a subsequent risk of stroke in the general population.

Associations between thrombophilic risk factors and determinants of atherosclerosis and inflammation in patients with non-arteritic anterior ischaemic optic neuropathy

Non-arteritic anterior ischaemic optic neuropathy (NAION) is caused by ischaemia of the optic nerve head. The pathophysiology of NAION is unclear, and no proven effective treatment exists. Patients, methods: We analyzed thrombophilic risk factors and determinants of atherosclerosis and inflammation in 109 consecutive patients and 109 age- and sex-matched volunteers using a case-control design. Results: High levels of fibrinogen (>384 mg/dl; OR 3.2, p = 0.003), factors VIII:C (>183%; OR 2.6, p = 0.02), IX (>153%; OR 2.6, p = 0.026), XI (>142%; OR 3.4, p = 0.006), von Willebrand factor (activity >205%; OR 3.1, p = 0.005; antigen >194%; OR 3.5, p = 0.002), and triglycerides (>228 mg/dl; OR 2.8, p = 0.026), higher platelet counts (>294 000/[uni03BC]l; OR 2.5, p = 0.04), low levels of HDL cholesterol (<40 mg/dl; OR 2.7, p = 0.032), and an accelerated erythrocyte sedimentation rate (>20 mm/h; OR 4.4, p = 0.003) were associated with NAION. Conclusion: Our findings support the contention of a complex pathogenesis of NAION resulting from the coincidence of proatherogenic, prothrombotic and proinflammatory processes. The alterations described could be causative, side effects, or just coincidental findings.

Bilateral vision loss due to Leber's hereditary optic neuropathy after long-term alcohol, nicotine and drug abuse

PURPOSE

Leber's hereditary optic neuropathy is relatively rare, and no clinical pathognomonic signs exist. We present a rare case of bilateral vision loss of a patient with multiple drug abuse in the history.

OBSERVATION

A 31-year-old man presented with a history of progressive, decreased vision in both eyes for 6 month. On examination, his visual acuity was hand motion in both eyes. Funduscopy demonstrated a temporal pallor of the optic disc. Goldmann visual field perimetry showed a crescent visual field in the right eye and a circular decrease to less than 50 ° in the left eye. Electroretinogram showed a scotopic b-wave amplitude reduction. Optical coherence tomographies, Heidelberg Retina tomography, visual evoked potentials, and magnetic resonance imaging with contrast as well as blood tests were normal. The patient reported to consume various kinds of drugs as well as recreational drug use and alcohol consumption since he was 16 years old. We started a hemodilution therapy, believing the patient suffered from a bilateral, toxic optic neuropathy due to his lifestyle. Laboratory results later on showed Leber's hereditary optic neuropathy.

CONCLUSION AND IMPORTANCE

Leber's hereditary optic neuropathy is a rare disease without a typical, pathognomonic presentation. Even though the patient gave good reasons for a toxic optic neuropathy, one should never stop to test for other diseases.

Review of the association between retinal microvascular characteristics and eye disease

Computerized retinal imaging technologies enable the static and dynamic measurement of a range of retinal microvascular parameters. Large population-based studies have reported associations between these microvascular indices and various ophthalmic diseases including diabetes, age-related macular degeneration, retinal artery embolism, retinal vein occlusion, glaucoma and non-glaucomatous optic neuropathies. Increasingly, sophisticated imaging and analysis techniques have the potential to provide relevant clinical information regarding disease risk and progression; however, further studies are required to verify associations and strengthen the predictive power of these techniques. We summarize the current state of knowledge regarding retinal microvascular characteristics and eye disease.

Optic Nerve Head Elastometry in Both Eyes of Patients with Unilateral Non-arteritic Anterior Ischaemic Optic Neuropathy - May It Be a Novel Aspect of the Pathogenesis?

In this prospective study, the biomechanical properties of optic nerve head (ONH) and cornea in both eyes of patients with non-arteritic anterior ischaemic optic neuropathy and healthy control eyes were investigated. ONH elastometry was measured with real-time elastography, and corneal elastometry was measured with ocular response analyser. Elastometry of cornea and ONH was lower in both eyes of patients with unilateral non-arteritic ischaemic optic neuropathy than in healthy control eyes. The role of these biomechanical differences in the pathogenesis of non-arteritic ischaemic optic neuropathy should be investigated further.

Can Corneal Biomechanical Properties Give Clues About Elasticity of Optic Nerve Scleral Component in Nonarteritic Anterior Ischemic Optic Neuropathy?

OBJECTIVE

To investigate corneal biomechanical properties among individuals with unilateral nonarteritic anterior ischemic optic neuropathy (NAION) compared to healthy gender- and age-matched subjects.

METHODS

The study subjects were separated into 2 groups: 66 eyes of 33 patients with unilateral NAION (study group) and 33 eyes of 33 healthy individuals (control group). Reichert ocular response analyzer (Reichert Ophthalmic Instruments) was used to assess corneal hysteresis (CH), corneal resistance factor (CRF), corneal-compensated intraocular pressure (IOPcc), and Goldmann-correlated intraocular pressure values. Also, central corneal thickness was measured using Scheimpflug camera combined with a Placido disc corneal topographer (Sirius; Costruzioni Strumenti Oftalmici).

RESULTS

Mean CH and median CRF values were significantly lower in the affected eyes (8.8 ± 1.8 mm Hg, 9.4 mm Hg, respectively) and contralateral unaffected eyes (9.1 ± 1.6 mm Hg, 9.8 mm Hg, respectively) of NAION patients than those in the control group (9.9 ± 1.3 mm Hg, 10.4 mm Hg, respectively; all P < 0.017). Mean IOPcc was significantly higher in the affected eyes of NAION patients (19.2 ± 3.5 mm Hg) than in the eyes of control group (17.1 ± 3.6 mm Hg; P = 0.002).

CONCLUSIONS

CH and CRF are significantly reduced in patients with NAION, possibly indirectly reflecting structural weakness in the lamina cribrosa.

Carotid artery intimal medial thickness and carotid artery plaques in hypertensive patients with non-arteritic anterior ischaemic optic neuropathy

PURPOSE

To assess the correlation of carotid artery intimal medial thickness (C-IMT) and carotid artery plaque score (CPS) of the common carotid artery with non-arteritic anterior ischemic optic neuropathy (NAION) in hypertensive patients.

METHODS

This case-control study recruited 192 subjects. Forty-eight patients had NAION with systemic hypertension, 46 had hypertension without visual complaints, and 98 were normal controls. C-IMT and common carotid arterial plaque were measured by high-resolution vascular ultrasonography.

RESULTS

High-density lipoprotein (HDL) in patients with NAION (1.24 ± 0.31) was significantly lower than that of the Hypertensive group (1.39 ± 0.30, P = 0.034). The C-IMT in the affected side of patients with NAION (1.00 ± 0.23) was significantly increased compared to the unaffected side (0.83 ± 0.19, P < 0.001), the Hypertensive group (0.83 ± 0.17, P < 0.001), and the Normal group (0.69 ± 0.16, P < 0.001). The presence of carotid artery plaque was more frequent in the patients with NAION, compared to either the Hypertensive group (P = 0.001) or the Normal group (P < 0.001). By multiple regression analysis, lower high-density lipoprotein (HDL) (P = 0.009), thicker C-IMT (P = 0.002), CPS Grade = 1 (P = 0.028), and Grade = 2 (P = 0.005) were associated with increased NAION risk, when the NAION group compared with the Hypertensive group (OR > 1.0). Systolic blood pressure (P = 0.001), thicker C-IMT (P < 0.001), CPS Grade = 1 (P = 0.006), Grade = 2 (P = 0.002), and Grade = 3 (P = 0.015) were associated with increased NAION risk, when the NAION group compared with the Normal group (OR > 1.0).

CONCLUSIONS

C-IMT and CPS were associated with NAION in hypertensive patients, suggesting that NAION might be associated with carotid artery atherosclerosis. This association may be due to similar pathological changes of the inner vascular walls in the carotid artery and the arteries supplying the optic nerve head.

Risk Factors for Non-arteritic Anterior Ischaemic Optic Neuropathy in a Korean Population

To determine the risk factors for non-arteritic anterior ischaemic optic neuropathy (NAION) in Korean patients, medical records from 45 Korean patients group and 45 healthy controls group were retrospectively reviewed. 10 NAION risk factors, including age, sex, associated systemic disease, past medical/social history, and fundus findings were analyzed. Significant risk factors for NAION in Korean patients were diabetes mellitus (odds ratio (OR) = 3.613, p = 0.020), hypercholesterolaemia (OR = 5.200, p = 0.001), smoking (OR = 3.58, p = 0.014), microaneurysm/haemorrhage (OR = 5.375, p = 0.024), and crowded small cup (OR = 17.200, p < 0.001).

Imaging of macrophage dynamics with optical coherence tomography in anterior ischemic optic neuropathy

Anterior ischemic optic neuropathy (AION) is a relatively common cause of visual loss and results from hypoperfusion of the small arteries of the anterior portion of the optic nerve. AION is the leading cause of sudden optic nerve related vision loss with approximately 10 cases per 100'000 in the population over 50 years. To date there is no established treatment for AION and therefore a better understanding of the events occurring at the level of the optic nerve head (ONH) would be important to design future therapeutic strategies. The optical properties of the eye allow imaging of the optic nerve in vivo, which is a part of the CNS, during ischemia. Experimentally laser induced optic neuropathy (eLiON) displays similar anatomical features as anterior ischemic optic neuropathy in humans. After laser induced optic neuropathy we show that hyperreflective dots in optical coherence tomography correspond to mononuclear cells in histology. Using fluorescence-activated flow cytometry (FACS) we found these cells to peak one week after eLiON. These observations were translated to OCT findings in patients with AION, where similar dynamics of hyperreflective dots at the ONH were identified. Our data suggests that activated macrophages can be identified as hyperreflective dots in OCT.

Demographic, Systemic, and Ocular Factors Associated with Nonarteritic Anterior Ischemic Optic Neuropathy

OBJECTIVE

Nonarteritic anterior ischemic optic neuropathy (NAION) is a devastating ocular condition causing permanent vision loss. Little is known about risk factors for developing this disease. We assessed demographic, systemic, and ocular factors associated with NAION.

DESIGN

Retrospective longitudinal cohort study.

PARTICIPANTS

Beneficiaries between 40 and 75 years old without NAION at baseline enrolled in a large U.S. managed care network.

METHODS

Enrollees were monitored continuously for ≥2 years between 2001 and 2014 to identify those newly diagnosed with NAION (International Classification of Diseases, 9th Revision, Clinical Modification [ICD-9-CM] code 377.41). All persons were under ophthalmic surveillance and all cases had ≥1 confirmatory ICD-9-CM code for NAION during follow-up.

MAIN OUTCOME MEASURES

Multivariable Cox regression modeling was used to generate hazard ratios (HRs) with 95% confidence intervals (CIs) to describe the statistical relationship between selected demographic characteristics, systemic and ocular conditions, and the hazard of developing NAION.

RESULTS

Of 1 381 477 eligible enrollees, 977 (0.1%) developed NAION during a mean ± standard deviation (SD) follow-up of 7.8±3.1 years. The mean ± SD age for NAION cases at the index date was 64.0±9.2 years vs. 58.4±9.4 years for the remainder of the beneficiaries. After adjustment for confounding factors, each additional year older was associated with a 2% increased hazard of NAION (HR = 1.02; 95% CI: 1.01-1.03). Female subjects had a 36% decreased hazard of developing NAION (HR = 0.64; 95% CI: 0.55-0.74) compared with male subjects. Compared with whites, Latinos had a 46% decreased hazard of developing NAION (HR = 0.54; 95% CI: 0.36-0.82), whereas African ancestry was not significantly associated with NAION (HR = 0.91; 95% CI: 0.72-1.15). Systemic diseases associated with NAION included hypertension (HR = 1.62; 95% CI: 1.26-2.07) and hypercoagulable states (HR = 2.46; 95% CI: 1.51-4.00). Although diabetes mellitus (DM) was not significantly associated with NAION compared with those without DM (P = 0.45), patients with end-organ involvement from DM had a 27% increased hazard of NAION relative to those with uncomplicated DM (HR = 1.27; 95% CI: 1.01-1.59). Ocular diseases associated with NAION were age-related macular degeneration (HR = 1.29; 95% CI: 1.08-1.54) and retinal vein occlusion (HR = 3.94; 95% CI: 3.11-4.99).

CONCLUSIONS

Our study identified several modifiable risk factors that may be associated with NAION. Should future studies confirm these findings, they may offer opportunities to prevent or treat this debilitating condition.

Analysis of Fundus Photography and Fluorescein Angiography in Nonarteritic Anterior Ischemic Optic Neuropathy and Optic Neuritis

Purpose

We evaluated fundus and fluorescein angiography (FAG) findings and characteristics that can help distinguish nonarteritic anterior ischemic optic neuropathy (NAION) from optic neuritis (ON).

Methods

Twenty-three NAION patients and 17 ON with disc swelling patients were enrolled in this study. We performed fundus photography and FAG. The disc-swelling pattern, hyperemia grade, presence of splinter hemorrhages, cotton-wool spots, artery/vein ratio and degree of focal telangiectasia were investigated. The FAG findings for each patient were compared with respect to the following features: the pattern of disc leakage in the early phase, arteriovenous (artery/vein) transit time (second), and the presence and pattern of the filling delay.

Results

Cotton-wool spots, focal telangiectasia, and venous congestion were more common in the affected eyes of NAION patients. Upon FAG, 76.5% of the patients in the ON group exhibited normal choroidal circulation. However, 56.5% of patients in the NAION group demonstrated abnormal filling defects, such as peripapillary, generalized, or watershed zone filling delays.

Conclusions

Fundus findings, including cotton-wool spots, focal telangiectasia, and venous congestion in the affected eye, may be clues that can be used to diagnose NAION. In addition, choroidal insufficiencies on FAG could be also helpful in differentiating NAION from ON.

Risk of Nonarteritic Anterior Ischemic Optic Neuropathy Following End-Stage Renal Disease

To investigate the risk of nonarteritic anterior ischemic optic neuropathy (NAION) following end-stage renal disease (ESRD).A retrospective, nationwide, matched cohort study.ESRD patients identified by the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) code 585.The study cohort included 93,804 ESRD patients registered with the Taiwan National Health Insurance Research Database between January 2000 and December 2009. An age- and sex-matched control group comprised 93,804 patients (case:control = 1:1) selected from the Taiwan Longitudinal Health Insurance Database 2000. Information for each patient was collected from the index date until December 2011. The incidence and risk of NAION were compared between the ESRD and control groups. The adjusted hazard ratio (HR) for NAION after adjustment for potential confounders was obtained by a Cox proportional hazard regression analysis. A Kaplan-Meier analysis was used to calculate the cumulative incidence rate of NAION.The incidence of NAION following ESRD.In total, 133 ESRD patients (0.14%) and 51 controls (0.05%) had NAION (P < 0.001) during the follow-up period, leading to a significantly elevated risk of NAION in the ESRD patients compared with the controls (incidence rate ratio = 3.14, 95% confidence interval [CI] = 2.11-4.67). After adjustment for potential confounders including diabetes mellitus, hypertension, hypotension, hyperlipidemia, and 2-way interaction terms between any 2 factors, ESRD patients were 3.12 times more likely to develop NAION than non-ESRD patients in the full cohort (adjusted HR = 3.12, 95% CI = 2.10-4.64). Additionally, patients with hypertension and hyperlipidemia showed higher incidence rates of NAION in the ESRD group compared with the controls: 2.31 (95% CI = 1.40-3.82) for hypertension and 2.72 (95% CI = 1.14-6.50) for hyperlipidemia.ESRD increased the risk of NAION, which is an interdisciplinary emergency. Close collaboration between nephrologists and ophthalmologists is important in NAION management following ESRD to prevent fellow eye involvement.

Mean Platelet Volume in Patients with Nonarteritic Anterior Ischemic Optic Neuropathy

Objective. We aimed to investigate the mean platelet volume (MPV) of the patients with nonarteritic anterior ischemic optic neuropathy (NAION). Methods. The medical records of 46 patients with the diagnosis of NAION and 90 control subjects were retrospectively evaluated. All participants underwent complete ocular examination including intraocular pressure (IOP) measurement. Hematocrit, MPV, hemoglobin, and platelet levels of the patients with NAION were compared with those of control subjects. Results. There was no significant difference between the groups in platelet counts (p = 0.76). NAION group had significantly higher MPV values (8.25 ± 1.26 fL) than that of control subjects (7.64 ± 1.01 fL) (p < 0.001). Multivariate logistic regression analysis showed that MPV is an independent predictor of NAION (odds ratio = 1.61; 95% confidence interval (CI) = 1.13–2.28; p = 0.007). The mean IOP was significantly higher in NAION group (p < 0.001). IOP was also found as an independent predictor of NAION according to the regression analysis (OR = 1.27; 95% CI = 1.08–1.48; p = 0.003). Conclusion. Our results demonstrated that the MPV values were significantly higher in NAION patients, suggesting that larger platelets may contribute to the pathogenesis of the NAION.

Current concepts in the diagnosis, pathogenesis and management of nonarteritic anterior ischaemic optic neuropathy

Nonarteritic anterior ischaemic optic neuropathy (NAION) is the most common acute optic neuropathy in patients over the age of 50 and is the second most common cause of permanent optic nerve-related visual loss in adults after glaucoma. Patients typically present with acute, painless, unilateral loss of vision associated with a variable visual field defect, a relative afferent pupillary defect, a swollen, hyperaemic optic disc, and one or more flame-shaped peripapillary retinal haemorrhages. The pathogenesis of this condition is unknown, but it occurs primarily in patients with structurally small optic discs that have little or no cup and a variety of underlying vascular disorders that may or may not be known at the time of visual loss. There is no consistently beneficial medical or surgical treatment for the condition, but there are now animal models that allow testing of various potential therapies. About 40% of patients experience spontaneous improvement in visual acuity. Patients in whom NAION occurs in one eye have a 15-19% risk of developing a similar event in the opposite eye over the subsequent 5 years.

The association between diabetes mellitus and nonarteritic anterior ischemic optic neuropathy: a systematic review and meta-analysis

Background

The association of diabetes mellitus (DM) with nonarteritic anterior ischemic optic neuropathy (NAION) has been inconclusive.

Purpose

To determine whether DM is associated with an increased risk of NAION.

Methods

A comprehensive literature search was performed for published studies reporting both DM and NAION based on PubMed and EMBASE. After reviewing characteristics of all the included studies systematically, meta-analytical method was employed to calculate the pooled odds ratio (OR) and associated 95% confidence interval (CI) from random-effects models. Heterogeneity was assessed by Q-statistic test. Funnel Plot, Begg's and Egger's linear regression test were applied to evaluate publication bias. A sensitivity analysis and meta-regression analysis were also performed to assess the robustness of results.

Results

2,096 participants from 12 case-control studies were pooled for a meta-analysis. The result of meta-analysis of these studies indicated that DM is associated with increased risk of NAION (pooled OR = 1.64, 95% CI = 1.17–2.30; P = 0.004). Sensitivity analysis indicated our findings are robust, and meta-regression analysis revealed no significant effect in terms of geographical area, gender, age of patients with NAION, the year of the publication, source of the controls, and sample size (all p>0.05). Evidence of publication bias was not observed in our study.

Conclusion

Meta-analysis suggests that DM might be associated with increased risk of NAION.

A case of anterior ischemic optic neuropathy associated with uveitis

Introduction:

Here, we describe a patient who presented with anterior ischemic optic neuropathy (AION) and subsequently developed uveitis.

Case:

A 69-year-old man was referred to our hospital and initially presented with best-corrected visual acuities (BCVA) of 20/40 (right eye) and 20/1000 (left eye) and relative afferent pupillary defect. Slit-lamp examination revealed no signs of ocular inflammation in either eye. Fundus examination revealed left-eye swelling and a pale superior optic disc, and Goldmann perimetry revealed left-eye inferior hemianopia. The patient was diagnosed with nonarteritic AION in the left eye. One week later, the patient returned to the hospital because of vision loss. The BCVA of the left eye was so poor that the patient could only count fingers. Slit-lamp examination revealed 1+ cells in the anterior chamber and the anterior vitreous in both eyes. Funduscopic examination revealed vasculitis and exudates in both eyes. The patient was diagnosed with bilateral panuveitis, and treatment with topical betamethasone was started. No other physical findings resulting from other autoimmune or infectious diseases were found. No additional treatments were administered, and optic disc edema in the left eye improved, and the retinal exudates disappeared in 3 months. The patient’s BCVA improved after cataract surgery was performed.

Conclusion:

Panuveitis most likely manifests after the development of AION.

Bilateral consecutive optic neuropathy in a patient with thrombophilia

A 39-year-old man was admitted with a sudden visual loss in the left eye. Visual acuities were 10/10 on the right and 1/10 on the left. Fundus examination did not show any abnormalities. Visual acuity improved to 10/10 and visual field defect regressed in the following 2 weeks. Three years later, the patient returned with acute visual loss in the right eye. Visual acuities were 2/10 on the right and 10/10 on the left. Right optic disc had blurred margins with mild oedema. The tests revealed methylenetetrahydrofolate reductase A1298C mutation with positive lupus anticoagulant and hyperhomocysteinaemia. Enoxaparin was initialised with vitamin B12 supplementation. Complete visual recovery occurred in the following 3 weeks in both eyes. Thrombophilic screening seems to be important in the treatment and prevention of an attack in the second eye of patients with non-arteritic anterior ischaemic optic neuropathy.

The Pathogenesis of Nonarteritic Anterior Ischemic Optic Neuropathy

Although nonarteritic anterior ischemic optic neuropathy (NAION) is known to occur as a result of ischemic insult to the anterior portion of the optic nerve, its etiology and pathogenesis remain elusive. Because NAION is a nonfatal condition, acute, postmortem histopathologic analysis has never been undertaken. Animal models of NAION have been created with the use of an iodinated derivative of fluorescein, rose bengal. When rose bengal is stimulated with the use of a frequency-doubled neodymium-Yttrium aluminium garnet (YAG) laser diode, vascular endothelial damage may be induced in a precise and focal manner, within the anterior optic nerve. Primate and nonprimate animal models of NAION differ from the human pattern of NAION in the duration of the disease course, as well as the anatomy. The rat lamina cribrosa contains a differing connective tissue structure, which may result in a differing pathogenesis of ischemic insult. Optic disk swelling resolves within 5 days in rats and 14 days in primates; in humans, it is known to persist for up to 6 weeks. Animal models have nonetheless enabled a deeper understanding of the underlying pathologic processes in NAION.

Glucose-6-phosphate dehydrogenase deficiency and diabetes mellitus with severe retinal complications in a Sardinian population, Italy

BACKGROUND

Glucose-6-Phosphate Dehydrogenase (G6PD) deficiency is one of the most common human genetic abnormalities, with a high prevalence in Sardinia, Italy. Evidence indicates that G6PD-deficient patients are protected against vascular disease. Little is known about the relationship between G6PD deficiency and diabetes mellitus. The purpose of this study was to compare G6PD deficiency prevalence in Sardinian diabetic men with severe retinal vascular complications and in age-matched non-diabetic controls and ascertain whether G6PD deficiency may offer protection against this vascular disorder.

METHODS

Erythrocyte G6PD activity was determined using a quantitative assay in 390 diabetic men with proliferative diabetic retinopathy (PDR) and 390 male non-diabetic controls, both aged ≥50 years. Conditional logistic regression models were used to investigate the association between G6PD deficiency and diabetes with severe retinal complications.

RESULTS

G6PD deficiency was found in 21 (5.4 %) diabetic patients and 33 (8.5 %) controls (P=0.09). In a univariate conditional logistic regression model, G6PD deficiency showed a trend for protection against diabetes with PDR, but the odds ratio (OR) fell short of statistical significance (OR=0.6, 95% confidence interval=0.35-1.08, P=0.09). In multivariate conditional logistic regression models, including as covariates G6PD deficiency, plasma glucose, and systemic hypertension or systolic or diastolic blood pressure, G6PD deficiency showed no statistically significant protection against diabetes with PDR.

CONCLUSIONS

The prevalence of G6PD deficiency in diabetic men with PDR was lower than in age-matched non-diabetic controls. G6PD deficiency showed a trend for protection against diabetes with PDR, but results were not statistically significant.